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DIY Stompboxes => Building your own stompbox => Topic started by: frequencycentral on January 05, 2009, 03:32:11 PM

Title: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 05, 2009, 03:32:11 PM
I got a bunch of 5672 submini pentodes last summer, and have been busy designing uses for them. You may have seen the 'Pentadriver', 'Pentaboost' and 'Red Star Drive' threads.

I thought it was about time I tried an amp design, so here's "Murder One"

(http://i210.photobucket.com/albums/bb292/frequencycentral/MurderOneV1.jpg)

I need you guys help to finish it - to optimise it really. I've never built or designed a tube amp before. Obviously it's not ever going to be LOUD, but is at the moment comfortably loud enough for practice. So, without radically changing the design concept (which I don't want to do) what have I missed and what can I change for the better?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: dwan on January 05, 2009, 04:31:28 PM
Hello Rick

As a beginner, i would only replace all the caps with higher-rated ones, as a 8v margin is dangerously close to a surprise-blow-up-in-ya-face. The closer to their rating they are, the less they last. Unless you want to stick to a 12v main voltage, i would also go with more "elegant" way to get your voltages (transfo), as you're using the 1044 over its limits.

Very interesting tube builds nonetheless, i've ordered some 5672's last week to build and tweak my very own pentadriver  :icon_biggrin:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 05, 2009, 05:18:14 PM
Hello Rick

As a beginner, i would only replace all the caps with higher-rated ones, as a 8v margin is dangerously close to a surprise-blow-up-in-ya-face. The closer to their rating they are, the less they last. Unless you want to stick to a 12v main voltage, i would also go with more "elegant" way to get your voltages (transfo), as you're using the 1044 over its limits.

Very interesting tube builds nonetheless, i've ordered some 5672's last week to build and tweak my very own pentadriver  :icon_biggrin:

Yup, I'll have to get some 100 volt rated caps anyway, as I'm thinking maybe to try a few more stages with the MAX1044 to get up to about 80 volts. The volume increase with the incremental increases in the plate voltage is startling.

I really wanted to test this theory that a MAX1044 could power the plates of a tube amp - I was expecting sag, but there is no sag. I've never worked with high voltages, and I kinda want this amp to be accessible to everyone buildwise, so a power transformer is not an option. I just want to see how much mileage can be got out of this design concept without resorting to high voltage/power transformer.

Yeah yeah I know the MAX1044 is operating outside it's spec, I have 20 of them so I can afford to be a bit blase about it. IMHO they survive at 12 volts. To be honest, I wasn't even sure this concept would work out at all, now that it has I'll invest in some LT1054S (more ma, and rated for 12 volts) to replace the MAX1044. Alternatively, there's no reason why not to use a 9 volt supply instead of 12 volts.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Br4d13y on January 05, 2009, 06:27:48 PM
( silently waiting for adriano to come around witha vero board.....) :icon_mrgreen: :icon_mrgreen:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 05, 2009, 06:51:01 PM
( silently waiting for adriano to come around witha vero board.....) :icon_mrgreen: :icon_mrgreen:

I'm sure he'll be along when the Rome wine bars close.......... ;)

I forgot to put a cap in the schematic. It should go to ground from where those two 100R resistor connect by the transformer. I'm using a 33uf at the moment, I have no idea what value it should be, but Valve Wizard (http://www.valvewizard.co.uk/) says there should be one there. It seems to work the same without though. Heyho, it's a 'work in progress' so i'll update the schematic as I go.

I'm running this into a 12" 8 ohm speaker by the way. I'm really pleased with the tone!

Anyone guess where I got the name "Murder One" from yet?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: davent on January 05, 2009, 09:33:52 PM
( silently waiting for adriano to come around witha vero board.....) :icon_mrgreen: :icon_mrgreen:

I'm sure he'll be along when the Rome wine bars close.......... ;)

I forgot to put a cap in the schematic. It should go to ground from where those two 100R resistor connect by the transformer. I'm using a 33uf at the moment, I have no idea what value it should be, but Valve Wizard (http://www.valvewizard.co.uk/) says there should be one there. It seems to work the same without though. Heyho, it's a 'work in progress' so i'll update the schematic as I go.

I'm running this into a 12" 8 ohm speaker by the way. I'm really pleased with the tone!

Anyone guess where I got the name "Murder One" from yet?
Hello,

I'll bite, every passive component is a 1 value multiplied or divided by 10 to the power of x.   A murder of crows is a group of crows so in your case you have a group of 1 valued components hence "Murder 1"

dave
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Br4d13y on January 05, 2009, 10:58:36 PM
( silently waiting for adriano to come around witha vero board.....) :icon_mrgreen: :icon_mrgreen:

I'm sure he'll be along when the Rome wine bars close.......... ;)

I forgot to put a cap in the schematic. It should go to ground from where those two 100R resistor connect by the transformer. I'm using a 33uf at the moment, I have no idea what value it should be, but Valve Wizard (http://www.valvewizard.co.uk/) says there should be one there. It seems to work the same without though. Heyho, it's a 'work in progress' so i'll update the schematic as I go.

I'm running this into a 12" 8 ohm speaker by the way. I'm really pleased with the tone!

Anyone guess where I got the name "Murder One" from yet?
Hello,
I'l bite, every passive component is a 1 value multiplied or divided by 10 to the power of x.   A murder of crows is a group of crows so in your case you have a group of 1 valued components hence "Murder 1"

dave


Brilliant!!!!!!!!!!!!!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: anti-idiot on January 05, 2009, 11:44:20 PM
( silently waiting for adriano to come around witha vero board.....) :icon_mrgreen: :icon_mrgreen:

I'm sure he'll be along when the Rome wine bars close.......... ;)

I forgot to put a cap in the schematic. It should go to ground from where those two 100R resistor connect by the transformer. I'm using a 33uf at the moment, I have no idea what value it should be, but Valve Wizard (http://www.valvewizard.co.uk/) says there should be one there. It seems to work the same without though. Heyho, it's a 'work in progress' so i'll update the schematic as I go.

I'm running this into a 12" 8 ohm speaker by the way. I'm really pleased with the tone!

Anyone guess where I got the name "Murder One" from yet?
Hello,

I'll bite, every passive component is a 1 value multiplied or divided by 10 to the power of x.   A murder of crows is a group of crows so in your case you have a group of 1 valued components hence "Murder 1"

dave

i was about to say "because you're fan of Lemmy Kilmister", but that "value of one" thingy makes more sense.

("Murder One" is the name of Lemmy's modded Marshall bass amp)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 06, 2009, 01:27:02 AM
I'll bite, every passive component is a 1 value multiplied or divided by 10 to the power of x.   A murder of crows is a group of crows so in your case you have a group of 1 valued components hence "Murder 1"

Very nice! But.................

i was about to say "because you're fan of Lemmy Kilmister", but that "value of one" thingy makes more sense.

("Murder One" is the name of Lemmy's modded Marshall bass amp)

Winner! I am a longtime fan of popular Brit beat combo Motorhead. My amp is about as loud as a wart on Lemmy's chin.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: ~arph on January 06, 2009, 03:32:01 AM
Have you tried the BJT trick at the plates to get more output? or doesn't that work with a charge pump.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 06, 2009, 01:32:09 PM
Have you tried the BJT trick at the plates to get more output? or doesn't that work with a charge pump.

I haven't tried that - the BJT would have to be rated suitably for the B+ voltage though. I think it's not a route I will take anyway - applying it to the first stage (preamp) would just overdrive the second stage (power amp), and I would rather keep it clean and add overdrive via a pedal. There is no point in appling it to the second stage anyway, as the transformer is directly connected to B+.

I think I've pretty much decided to add some more voltage increase stages to the MAX1044 and see how much more power I can get. The 5672 maximum rating is 90 volts, at the moment I'm running at half of that.

The sound is that of a cranked up tube amp, but without upsetting the neighbours/causing plaster to fall from the ceiling.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: anti-idiot on January 06, 2009, 01:40:24 PM
I'll bite, every passive component is a 1 value multiplied or divided by 10 to the power of x.   A murder of crows is a group of crows so in your case you have a group of 1 valued components hence "Murder 1"

Very nice! But.................

i was about to say "because you're fan of Lemmy Kilmister", but that "value of one" thingy makes more sense.

("Murder One" is the name of Lemmy's modded Marshall bass amp)

Winner! I am a longtime fan of popular Brit beat combo Motorhead. My amp is about as loud as a wart on Lemmy's chin.

Lemmy's the man. But I bet your amp wouldn't survive a nuclear bombing. Lemmy (and Keith) would. He has more chemicals in his body than most of the stuff we use to make pedals.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on January 06, 2009, 02:40:56 PM
Looking quite nice!

Have you given any thought to the possibility of a tonestack?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 06, 2009, 02:46:07 PM
Looking quite nice!

Have you given any thought to the possibility of a tonestack?

Maybe. I'll see how much volume I have once I've added a few more voltage increase stages. Tonestacks always cause volume loss.  :icon_cry:
Title: "Murder One" - Submini Pentode, Low Voltage
Post by: Renegadrian on January 06, 2009, 07:08:03 PM
( silently waiting for adriano to come around witha vero board.....) :icon_mrgreen: :icon_mrgreen:

I'm sure he'll be along when the Rome wine bars close.......... ;)

You men made me laugh!!! eheheh You really figure me like this?! --->(http://digilander.libero.it/le.faccine/faccinea/mangia%20e%20beve/00041026.gif)
ok maybe I'm like this sometimes...I had new year's eve in tuscany, go figure...

Back IT and being serious (one time) - I'll work at it in the next days!!! THX Rick for another funny tube project!!!



that transformer is about 15$...Are there any cheaper subs?! Radio shak or something?
Title: Re: "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 06, 2009, 07:24:09 PM
that transformer is about 15$...Are there any cheaper subs?! Radio shak or something?

Mine is a clone with the same spec from an ebayer in Portugal - cheaper than having a fender shipped from USA - just do a search for 'fender reverb transformer'. The genuine Fender part is a little prettier though.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Renegadrian on January 06, 2009, 07:39:13 PM
Found THIS ONE (http://www.musikding.de/product_info.php/info/p1203_Reverb-Transformer.html) but it's not that cheaper, I guess I have to search for it better...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: chillhuman on January 06, 2009, 07:58:33 PM
My amp is about as loud as a wart on Lemmy's chin.
What speaker do you have plugged in? If you wire up something really efficient, you'd be AMAZED at how loud even 1W can be.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 07, 2009, 11:19:07 AM
My amp is about as loud as a wart on Lemmy's chin.
What speaker do you have plugged in? If you wire up something really efficient, you'd be AMAZED at how loud even 1W can be.

I'm running it into the 12" speaker of my Roland Bolt 60 tube combo, the speaker is not labelled, but is pretty good.

I got the voltage up to 60 volts last night by adding a couple more stages to the MAX1044, so I got another volume increase - nice! But I've run out of suitable caps to go all the way to 90 volts, I'll pick some up very soon.

I have decided to add two Si diodes between the 12 volt supply and the MAX1044's input to limit the voltage going into the MAX1044 to 10.6 volts, which is just a smidge above it's spec. Better safe than sorry.

I'm also planning to try Ge diodes in the voltage doubling matrix, as they have lower voltage drop that Si - and I have hundreds of them. R.G's Geofex article about the MAX1044 suggests zeners for even less losses - I don't have many, so I'll go with Ge and try to get as close to 90 volts (the 5672's maximum spec) as I can. I think I'll end up with eight stages of voltage increase, so 16 diodes and 16 caps.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on January 07, 2009, 12:40:50 PM
I almost wonder if you would be better of with a power transformer to supply B+, because the 317 can handle up to 60V in if I remember right.  Seems that if you had a higher input voltage (even without a dedicated power transformer) you could still get your 1.5V with the 317 but reduce the number of components.  I don't know, just seems like if you stack up 16 stages, that would be rather space consuming.  Just a thought.  Maybe you could even make it phantom powered (though I am not sure a phantom supply would provide enough current).  Are you thinking of supplying the 12VDC with a power supply or batteries or what?
Title: "Murder One"
Post by: Renegadrian on January 07, 2009, 12:50:22 PM
I think I'll end up with eight stages of voltage increase, so 16 diodes and 16 caps.

you mean 8 and 8...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 07, 2009, 12:54:47 PM
I almost wonder if you would be better of with a power transformer to supply B+, because the 317 can handle up to 60V in if I remember right.  Seems that if you had a higher input voltage (even without a dedicated power transformer) you could still get your 1.5V with the 317 but reduce the number of components.  I don't know, just seems like if you stack up 16 stages, that would be rather space consuming.  Just a thought.  Maybe you could even make it phantom powered (though I am not sure a phantom supply would provide enough current).  Are you thinking of supplying the 12VDC with a power supply or batteries or what?

16 caps and 16 diodes will take up a lot less space than a PT! I want this to be a 'safe build' anyway - PTs can be a bit intimidating. I did consider phantom, but want it to be self contained. I may end up using a 220 ohm/1 watt voltage drop resistor for each tube's heater instead of the LM317. Not planning for batteries - I'm using a 500ma/12 volt wallwart.

I think I'll end up with eight stages of voltage increase, so 16 diodes and 16 caps.

you mean 8 and 8...

No, 16 and 16 - each voltage increment uses two caps and two diodes.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on January 07, 2009, 12:55:26 PM
I guess I didn't read the title description well enough, says "low voltage".  I'm an idiot, so never mind me.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 07, 2009, 01:08:20 PM
I guess I didn't read the title description well enough, says "low voltage".  I'm an idiot, so never mind me.

Yup, low voltage. That's the whole point of this design for me. I want a 'Ruby' type amp in term of size and volume but entirely tube. I want it to be an easy build for pedal builders (ie, me and Adriano!) who have never dealt with high voltages. It just occured to me a while ago that the MAX1044 and these little tiny pentodes could make that possible.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on January 07, 2009, 02:26:55 PM
This is an awesome idea for people like me who are a bit intimidated to try to build a tube amp from the ground up, bt want to try something a step up from a Ruby/Little Gem.
Thanks a lot man!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: DSV on January 08, 2009, 05:17:19 PM
Nice project!

I've got a few suggestions for the power supply:
- maybe the MAX1044 could be replced by a NE555 as an oscillator, which is lower cost, has a higher voltage rating, and provides much more current (up to 200mA for the non-CMOS versions)
- another method could be as in here: a CD4049 in order to create the alternate voltage, and the caps and diodes for multiplication (like in here http://www.sugardas.lt/~igoramps/grass_preamp.htm )
- Finally, with a simple transformer: http://www.sugardas.lt/~igoramps/tomato_preamp_rus.htm
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 08, 2009, 05:56:10 PM
Nice project!

I've got a few suggestions for the power supply:
- maybe the MAX1044 could be replced by a NE555 as an oscillator, which is lower cost, has a higher voltage rating, and provides much more current (up to 200mA for the non-CMOS versions)
- another method could be as in here: a CD4049 in order to create the alternate voltage, and the caps and diodes for multiplication (like in here http://www.sugardas.lt/~igoramps/grass_preamp.htm )
- Finally, with a simple transformer: http://www.sugardas.lt/~igoramps/tomato_preamp_rus.htm

Thanks!

This amp has a 555 PS, but the designer describes it as 'unsafe': http://www.jjs.at/electronic/class_a_subminiature.html
I don't know how to design a 555 based PS - but if you can, be my guest, I'll give it a go! The maximum voltage needs to be 90 volts.
The 4049 PS also looks interesting, i'll do some research there. i guess i just used ideas i was sure of and understood. I'm open to suggestions though.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Zben3129 on January 08, 2009, 08:00:32 PM
You could try a 120v to 24v transformer to power the amp. If you wire it in reverse, then a 12vac input will give you about 60v on the secondary. You could power the amp with a 12vac wall wart and avoid having any voltages higher than 60v in the actual amp, while using a transformer supply, which I think is a better option than the MAX.

Zach
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Zben3129 on January 08, 2009, 08:13:41 PM
NOTE ^

The 60v you get out of the transformer would be AC, not DC, which, after rectification, would actually give to higher than 60vDC (~ 83vDC). You may want the added voltage, but if you don't you could choose a different transformer.

Determine the HT you want, and then add 5 volts to that to get your target DC voltage (HT + 5v = Vt)

Once you have target voltage, divide it by 1.414 to get your secondary AC voltage you need to be supplied by the transformer (Vsec)

Once you have your secondary AC voltage, use this ratio to determine the transformer you should use.  (120v / 'x') = (Vsec / 12v)  where x is the desired value of the transformer secondary

For example, if you wanted an 78v B+, your Vt would be 83v. This divided by 1.414 would be 60v. Plugged into the equation this would read (120v / 'x') = (60v / 12v)   which when solved would show a 24v secondary. So you would use a 120v to 24v transformer (120v is always the primary).


Zach
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 17, 2009, 09:24:36 AM
I thought I'd update this thread with where I'm at right now. Here's the current configuration:

(http://i210.photobucket.com/albums/bb292/frequencycentral/MurderOneV2.jpg)

I've tried out loads of ideas, I'm pretty pleased with this one. I've decided to use a 6111 submini dual triode for the preamp, there is much more gain available than using a 5672 as a preamp. It sound nice and bright (much brighter and louder than another experiment I did which used two 6111, one as a preamp and one as a power amp). The clean sound is not as loud as I would like, but hey, I'm a dirty guy anyways. This design (http://www.jjs.at/electronic/class_a_subminiature.html) was one inspiration for my amp project - the designer also states that the clean sound is pretty quiet, so maybe I'm striving for something unobtanium anyway.

Each tube has its own voltage dop resistor, these are both pretty bulky but unavoidable.

It would appear that although the maximum voltage for a 5672 is 90 volts it's not possible to apply a 90 volt plate voltage via a transformer (though ok via a resistor). Here's what Jasper Oosthoek over at the AX84 forum has to say about that: "If 90 volts is the maximum for the tubes, you cannot use it with a transformer (resistor is not a problem). As soon as you get a signal in the transformer its primary AC voltage will swing around B+. This means that if the AC voltage is 30 volts peak to peak, the anode voltage of the tube will swing between 75 and 105 volts. 60 volts on the anode might be a lot safer and will enable you to have 60 volts AC P2P (30 to 90 volts)". So I'm sticking to about 60 volts. I've also added a couple of 1n4148 to limit the DC into the MAX1044 to about 10.6 volts.

For the voltage doubling stages I'm using caps rated above the voltage available at the relevant stage, this starts to become a problem over 60 volts, as 50 volt and 63 volt rated caps are small, but the 10uf 100 volt caps I ordered are huge in comparison. Maybe I'll be able to get some a little more compact.

I'm pretty sure that I'm going to go ahead and build this design as it stands, as it seems to be pretty well optimised within the design constraints.  My next amp will be a push/pull using two 5672 for the power amp running into a Hammond 125A, and a 6111 for the preamp/phase inverter. I'll again use the MAX1044 power supply at around 60 volts. I have to source a 125A in the UK before I can start on that one. I'm hoping for a little more volume so the clean tones are more meaningful - and it shall be named "Sub Atomic"!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: slacker on January 17, 2009, 09:54:24 AM
This amp has a 555 PS, but the designer describes it as 'unsafe'

I think DSV was talking about using the 555 as a charge pump, not in a switchmode powersupply. You can use a 555 in a similar way to the MAX1044 to multiply or invert voltages. There's an example here (http://home.pacbell.net/lengal/ip/cpump.pdf).

Quote
The 4049 PS also looks interesting, i'll do some research there. i guess i just used ideas i was sure of and understood. I'm open to suggestions though.

I've tried this and it works but I couldn't get much current out of it. Using it to triple 15 volts I could only get a couple of milliamps, this is probably fine for preamp tubes with large plate resistors but I don't think it will be enough current to drive the output transformer.

Out of interest how much current does your amp draw from the B+.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Br4d13y on January 17, 2009, 10:17:58 AM
mwahahaha now it is time to take all of ricks designs and make one tube multi-effect amp with subminis :icon_twisted:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 17, 2009, 11:49:29 AM
This amp has a 555 PS, but the designer describes it as 'unsafe'

I think DSV was talking about using the 555 as a charge pump, not in a switchmode powersupply. You can use a 555 in a similar way to the MAX1044 to multiply or invert voltages. There's an example here (http://home.pacbell.net/lengal/ip/cpump.pdf).

Quote
The 4049 PS also looks interesting, i'll do some research there. i guess i just used ideas i was sure of and understood. I'm open to suggestions though.

I've tried this and it works but I couldn't get much current out of it. Using it to triple 15 volts I could only get a couple of milliamps, this is probably fine for preamp tubes with large plate resistors but I don't think it will be enough current to drive the output transformer.

Out of interest how much current does your amp draw from the B+.

Ian, that 555 circuit you linked to - could you tell me some more about it? What would be the voltage output, and is it just a case of adding extra stages to get more volts like to MAX? Could the zeners be replaced with something a little more common? 1n4148? I'll breadboard it, but it seem to me the parts count is going to be similar to the MAX - yeah a 555 is cheaper than a MAX though. I guess I like the MAX as its really easy to understand whats going on.

I'm not sure how much current the amp is drawing from the B+, not sure how to measure that, and my DMM is pretty basic.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: slacker on January 17, 2009, 01:31:01 PM
No too sure about that circuit Rick it was just something google turned up. I simulated it using 1N4148 diodes and it doubles the voltage, I don't know if you can add extra stages.

I think the MAX 1044 or a similar dedicated chip is probably the way to go, I think I'm going to get an LT1054 to play about with.

You don't need anything fancy to measure the current draw, just put a 1 ohm resistor between the last diode from the MAX1044 and B+ and put a big cap from B+ to ground to stop the amp oscillating. Then measure the voltage drop across the 1ohm resistor and that's your current draw in milli amps.
If you haven't got any 1ohm resistors just use the smallest you've got and then use Ohms law to work out the current draw V/R = I
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on January 17, 2009, 03:12:22 PM
Some questions for you:
1: What is the cheapest one can find a transformer for this? Are there any other transformers that work that cost less?
2: How many watss do the 220k resistors need to be?
3: Where is the best place to get a MAX1044? I saw a couple at Futurelec, but they are so slow...
4: Can you just run this at 9v and get rid of the diodes before the MAX 044?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kurtlives on January 17, 2009, 03:27:29 PM
1. The transformer is cheap to start. Weber Speakers in the US sells them quite low.
2. You ask what the "watts" need to be a lot I see. Learn the formula.
    W = V^2/R
    Where V squared is the voltage dropped across the resistor. R is the resistance in ohms of the resistor.
   
    There are other ways to manipulate the formula but that's how I use it.
3. Most online stores sell that charge pump. Mouser, Digikey, Small Bear etc...
4. You could. Probably sound like crap though. Would be much darker and compressed from my experiences.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 17, 2009, 03:45:56 PM
I'm using 1/4 watt resistors throughout except for those specified.

Running on 9 volts will be fine, and yes those two diodes can be removed. I have to disagree with kurtlives here, it won't sound like crap, it will just be quieter, as the B+ output of the MAX will be lower. More volts = more volume. So, get the B+ back up by adding another stage of voltage increase with the MAX and it will be exactly the same.

You would also have to change the heater voltage drop resistors for 9 volts, so:

6111: 9 ohm / 1 watt (though 10 ohm would still be within tolerance)

5672: 155 ohm / 1/2 watt
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kurtlives on January 17, 2009, 03:56:12 PM
Rick that was just my personal opinion and I know you understand that. I find starved plate designs really open up at 25V or so.

Why do you use resistors for getting the filament voltage where you want it. I mean sure its great if you have a constant B+. But wouldn't a regulator make more sense, then if your B+ changes your filament voltage stages constant. That is if they make regulators for the filament voltage your trying to achieve.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 17, 2009, 04:03:09 PM
Rick that was just my personal opinion and I know you understand that. I find starved plate designs really open up at 25V or so.

Why do you use resistors for getting the filament voltage where you want it. I mean sure its great if you have a constant B+. But wouldn't a regulator make more sense, then if your B+ changes your filament voltage stages constant. That is if they make regulators for the filament voltage your trying to achieve.

Chris, I think you missed something here, the output of the MAX and therefore the B+ is 60 volts, so it's not a starve plate design at all.

As for the drop resistors, just keeping it simple. And assuming a nicely regulated power supply is used. You could use a 7806 for the 6111 and a LM317 for the 5672 I guess.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kurtlives on January 17, 2009, 04:12:49 PM
I am quite aware that the B+ will be 60V with the charge pump.

At 9V like was talked about though the amp would have "starved plates" and not be as good as it could be imo.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 17, 2009, 04:18:31 PM
At 9V like was talked about though the amp would have "starved plates" and not be as good as it could be imo.

4: Can you just run this at 9v and get rid of the diodes before the MAX 1044?

Yeah - without the MAX though you wouldn't hear anything!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on January 17, 2009, 04:40:15 PM
Thanks for the Weber tip Chris, I hadn't looked there.
Have you guys seen this?
https://taweber.powweb.com/store/pdlptsch.jpg
Looks quite useful.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 25, 2009, 05:32:48 PM
Fellow forum user .Mike has put me on to the Microchip brand 1044 - probably better suited to this project than Maxim's MAX1044, as you could lose the two 1n4148 between the DC input and the 1044:

Price: The Microchip TC1044S is about half the price-- $1.12 for one at Mouser, $0.93 each for 10+.
Supply voltage: The Microchip TC1044S handles 1.5v - 12v, with a 13v max.
Oscillator Boost: The Microchip TC1044S boosts to 45Khz, the MAX1044 boosts to about 30Khz.

Here is the Mouser link:

http://www.mouser.com/Search/Refine.aspx?Keyword=TC1044SCPA

Here's the data sheet:

http://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf

Thanks .Mike !!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on January 26, 2009, 09:18:31 PM
Right after I bought a few MAX1044's... thats the way it goes, I guess.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 27, 2009, 02:32:51 AM
Right after I bought a few MAX1044's... thats the way it goes, I guess.


I'm in the same boat right with you - I've got 10 Max1044's! But I run them at 12 volts anyways (don't tell R.G.!).
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: ~arph on January 28, 2009, 09:41:35 AM
Just a thought.. doesn't pin 5 output -V supply?

So you get -9V as well.. how about using that as GND so you have an additional 9V.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 28, 2009, 12:51:49 PM
Just a thought.. doesn't pin 5 output -V supply?

So you get -9V as well.. how about using that as GND so you have an additional 9V.

Well you would also have to use a 10uf cap from pin 5 to ground. And another 10uf cap between pins 2 and 4 -  I'm not sure if this would interfere with the use of pin 2 in the voltage doubling section. Maybe better just to use those two caps (plus two diodes) for another voltage doubling stage and keep it simple?

I'm hoping to finish mine by the weekend. I used six stages of doubling (12 caps, 12 1n4148), and am getting ~70 volts, which is perfect for the 5672. I accidentally ordered twenty 10uf / 100v which are much bigger than I expected - I've used them anyway as there was room in my enclosure, and they look kinda cool anyway. Can't wait to get it finished actually!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: forsakenrider on January 29, 2009, 12:54:42 AM
Wow. I will definitely build this!

I just wanted to say, I built the Class A amp from JJS with the PSU from the class AB amp:

(http://i23.photobucket.com/albums/b353/getpunched/DSC_0003-2.jpg)
(http://i23.photobucket.com/albums/b353/getpunched/DSC_0005-2.jpg)

And its freakin loud through a 4x12... too loud for an apartment.....
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 29, 2009, 05:10:45 PM
Wow. I will definitely build this!

I just wanted to say, I built the Class A amp from JJS with the PSU from the class AB amp:

(http://i23.photobucket.com/albums/b353/getpunched/DSC_0003-2.jpg)
(http://i23.photobucket.com/albums/b353/getpunched/DSC_0005-2.jpg)

And its freakin loud through a 4x12... too loud for an apartment.....

Hey forsakenrider that looks great!! Didn't fancy the switch mode PS? I might try this one in my next submini amp, it seems simple and pretty safe too: http://www.ledsales.com.au/kits/nixie_supply.pdf
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Jered on January 30, 2009, 01:04:30 AM
  Looks great! How does it sound, and how loud does it get?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: forsakenrider on January 30, 2009, 06:59:18 PM
Yeah the switch mode PSU scared me a bit. It sounds pretty damn good. There is quite a hum and there is nothing I can figure to get rid of it. I Ask the guy that designed it and he said because the submini amps are over driving the power tube the can be pretty noisy.

Its LOUD.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on January 30, 2009, 07:58:42 PM
Could you post a link for the project?  I find it quite interesting.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on January 30, 2009, 08:06:27 PM
Would 63v electrolytic caps work ok? pretty close to 60v, I know, but 100v are a lot bigger and more expensive.
Also, the 10uf cap before the 1044 doesn't need to be any higher than 12v, right?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: forsakenrider on January 30, 2009, 10:00:27 PM
Could you post a link for the project?  I find it quite interesting.

this is what I built. http://jjs.at/electronic/class_a_subminiature.html

But I am now going to order some more tubes and try this new design!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: davent on January 30, 2009, 10:35:40 PM
There's a Trainwreck build happening over at Amp Garage that uses that tube compliment you may be interested in. You need to register in order to see attachments. http://ampgarage.com/forum/viewtopic.php?t=6159

dave
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on January 31, 2009, 01:07:38 AM
Never mind my earlier post, I found some 10uf 100v electros that are small and cheap here:
http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=020-1296&ctab=1#Tabs
Hope this is useful.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 31, 2009, 06:02:55 AM
Yeah the switch mode PSU scared me a bit. It sounds pretty damn good. There is quite a hum and there is nothing I can figure to get rid of it. I Ask the guy that designed it and he said because the submini amps are over driving the power tube the can be pretty noisy.

Its LOUD.

Yeah, that fact that the voltage isnt predictable scared me too. The nixie PS I linked to has a regulating mechanism, which seems far more predictable to me. As for your hum - surely it must be a PS issue?

Would 63v electrolytic caps work ok? pretty close to 60v, I know, but 100v are a lot bigger and more expensive.
Also, the 10uf cap before the 1044 doesn't need to be any higher than 12v, right?

The 10uf / 100v I bought were cheap enough - but bigger than expected.

You are correct - the cap before the 1044 can be rated at 15 volts.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 31, 2009, 07:56:48 AM
Well my chassis is done now, I just have to do the off-board stuff. I'm using SIL sockets as connectors, so the top of the box (containing the input, output, on/off switch, DC socket and gain/volume controls) can be completely removed from the chassis. You can see how this works in the photo showing the transformer connection to the board. Hoping to get it finished today/tomorrow. Hoping it will fire up first time too! I've already tested the PS.

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0002-12.jpg)

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0001-10.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 31, 2009, 10:41:23 AM
Ok, finished (just about).

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0009-8.jpg)

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0008-5.jpg)

Fired up first time - excellent! Though it has some hum that isn't there on the version on my breadboard - strange, I would expect the breadboard version to be noisier. Hmm. Maybe I should use some screened cable. I'll work in it!

I'm also planning to add ultra bright LEDs insid the enclosure, just couldn't get them last time I went to my supplier.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: yertle on January 31, 2009, 03:29:56 PM
Nice build! I just started messing around with tubes on low-ish voltages, got a boost/od with a 12au7 on 40VDC on the breadboard right now and I also have some sub mini's around (5672, 6088 and 6418) so I might try your murder one amp when I can find the time for it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ice-9 on January 31, 2009, 03:35:50 PM
Congrats, thats a really nice looking build. Now that its finished any chance of a few sound clips please.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 31, 2009, 05:38:03 PM
Thanks for the kind comments.  ;)

The hum I mentioned - dodgy guitar lead - would you believe it?? I just was getting ready for a serious debug too! Darn it.

I'll get some clips together over the next week - got no microphone here at the moment.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on January 31, 2009, 05:44:10 PM
So I', assuming you used perfboard? How did that work out?
Title: F..K YEAH!!!
Post by: Renegadrian on January 31, 2009, 06:50:02 PM
Rick you're the man...God what a nice enclosure and a good amp you made...


(http://digilander.libero.it/le.faccine/faccinea/cartelli/00060031.gif)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 31, 2009, 06:51:20 PM
Murder in the dark:

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0011-4.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Darkness, Darkness on February 01, 2009, 07:02:25 AM

Nice creation !! Congratulations ! :)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on February 01, 2009, 06:27:42 PM
What kind of transformer did you use?  If you already mentioned it, then I must have missed it, but I don't think I saw it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 01, 2009, 06:33:43 PM
What kind of transformer did you use?  If you already mentioned it, then I must have missed it, but I don't think I saw it.

Its on the schematic - fender reverb transformer #22921, 22500ohm/8ohm. Mine is a clone, not fender, but same spec.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on February 01, 2009, 08:14:45 PM
Ha! I totally missed it.  Sorry for the dumb question.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: DiamondDog on February 02, 2009, 11:31:36 PM
Though it has some hum that isn't there on the version on my breadboard - strange, I would expect the breadboard version to be noisier.

The trafo position and angle look sub-optimal to me. There's a reason valve amps have a lot of space in them.  ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: ~arph on February 03, 2009, 03:47:11 AM
Where are all the diodes  :icon_confused:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 03, 2009, 04:11:42 AM
Though it has some hum that isn't there on the version on my breadboard - strange, I would expect the breadboard version to be noisier.

The trafo position and angle look sub-optimal to me. There's a reason valve amps have a lot of space in them.  ;)

The hum was a dodgy guitar lead - is quiet as a mouse now.  8)

Where are all the diodes  :icon_confused:

They are on the underside of the perf, 'surface mounted' between the legs of the caps. 1n4148 are so small, it was the logical thing to do - and saved some space.  :icon_smile:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on February 03, 2009, 01:06:37 PM
Rick (or anyone),

This amp design has caught my interest, but I'm a noob to the amp-building scene--where are the speaker connections located in the schematic?

My best guess would be that it goes on the leads of the transformer, but I'd want to be sure before building :)

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 03, 2009, 01:29:31 PM
Rick (or anyone),

This amp design has caught my interest, but I'm a noob to the amp-building scene--where are the speaker connections located in the schematic?

My best guess would be that it goes on the leads of the transformer, but I'd want to be sure before building :)



Oh yeah sorry. The fender reverb transformer has four wires coming out of it:

Two are for the primary winding - these go to the 5672's plate and B+, as shown in the schematic. I connected the 0 ohm to the plate and the 22500 ohm to B+

Two are the for the secondary winding - these go to the speaker. I connected the 0 ohm to ground and the 8 ohm to the speaker.

This was my first tube amp build too - first time I've used an output transformer too, so I'm assuming I got the poliarity of the transformer correct. Hey, it works!

(http://i210.photobucket.com/albums/bb292/frequencycentral/22921.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on February 03, 2009, 01:41:25 PM
Ok, thanks--I figured that's how it would go--but transformers are a little confusing to me sometimes, with all their taps and whatnot.

I have a larger trans from an old Bose powered speaker amp lying around...I may see if the specs are anywhere close to that. If not, I might put a Fender reverb trans on order :)

Have you thought about posting some clips?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 03, 2009, 01:51:20 PM
Have you thought about posting some clips?

Yes, I will post some clips, I just haven't got access to a mic until the end of the week. What I can tell you is:

- the clean sound is pretty quiet (as stated in an earlier post)

- with gain all the way up it's loud and raunchy.

- with a high gain pedal before it (I use my Valvecaster) it feeds back and sustains forever.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on February 03, 2009, 01:56:49 PM
cool, thanks :)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 03, 2009, 02:15:55 PM
cool, thanks :)

No problem. I should say that my design concept was to make a 12 volt tube amp where I could turn everything up full to get that sound that I would get if I dared to turn my 60 watt tube amp up full. Massive crunch, but reasonably eardrum and neighbour friendly. Hopefully I'll be able to plug it into a 4x12, mic it up, and it will sound like a huge stack going at full pelt. Good for home recording.

I'm planning another submini tube amp which should be much louder, so the clean sound will be more meaningful. Two 7327 submini dual triodes, 12 volt supply using a 555 switch mode to get 100's of volts, push/pull, Hammond 125a O/T. But that's a while away yet.......
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on February 03, 2009, 02:21:49 PM
Yeah, cranked-amp at suitable recording levels is what I'm after as well--I can get plenty of clean headroom elsewhere  :icon_cool:

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on February 03, 2009, 05:47:26 PM
So Rick, are you using the switching supply schem from the JJS place?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 03, 2009, 05:50:35 PM
So Rick, are you using the switching supply schem from the JJS place?

What - in the next design? No, but similar - planning to modify this one for more volts, it's more stable, as the BC547 regulates the output: http://www.ledsales.com.au/kits/nixie_supply.pdf
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: petemoore on February 04, 2009, 02:42:21 AM
  that sure looks like a neat workaround !
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on February 04, 2009, 10:37:19 AM
So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?

...or am I crazy?  :icon_smile:

I know it gets away from the original intent of the project, what with the whole submini focus and all, but I'm just looking at what I have on hand :)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 04, 2009, 12:30:03 PM
So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?

...or am I crazy?  :icon_smile:

I know it gets away from the original intent of the project, what with the whole submini focus and all, but I'm just looking at what I have on hand :)

Yup  - that should work just fine - and the 12AU7 heater would draw less power than the 6111 heater. Just wouldn't be quite as small.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on February 04, 2009, 12:48:59 PM
fantastic.

I'm thinking of using a 1590bb as the chassis--I don't really need it to be super small. my other alternative would be to build it into a combo setup. I may make the BB-sized 'head' first, then remove the bottom plate and screw it into place in a cab once I get done with tweaking.

Keep up the good work with these designs, man, I know plenty of people who are looking for a good sound from low-power recording amp.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on February 05, 2009, 01:06:40 AM
My idea for the power stage (or whatever you want to call it) :

(http://s301.photobucket.com/albums/nn71/svsguitarhero/th_MurderonePower.gif)

I'm sure there are more effective ways of doing it, maybe Perf with the diodes mounted on the underside like you mentioned doing.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: petemoore on February 05, 2009, 01:30:47 AM
So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?
  12au7 for starved plate...has been done, that is very starved, starting with a tube designed for 12v supply...will operate differently.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 05, 2009, 03:45:21 AM
So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?
  12au7 for starved plate...has been done, that is very starved, starting with a tube designed for 12v supply...will operate differently.

I think jacobyjd is saying that he's using 12 volts for the 12AU7 heater but 70 volts for it's plate, which should operate the same as the 6111. Are you thinking of 12U7 space charged tube (which I'm guessing wouldn't work in this application)?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 05, 2009, 03:49:34 AM
I'm sure there are more effective ways of doing it, maybe Perf with the diodes mounted on the underside like you mentioned doing.

+1, it can be made a lot more compactly on perf. I'm not a fan of vero - I find it limiting because you have to work in one plane, and cuts in the track cost space. Perf lets you work outwards in any direction, and no need for cuts.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on February 05, 2009, 08:23:27 AM
So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?
  12au7 for starved plate...has been done, that is very starved, starting with a tube designed for 12v supply...will operate differently.

I think jacobyjd is saying that he's using 12 volts for the 12AU7 heater but 70 volts for it's plate, which should operate the same as the 6111. Are you thinking of 12U7 space charged tube (which I'm guessing wouldn't work in this application)?

Right--from past discussions I've read, it appeared that the only functional difference between the 12au7 and the 6111 were the heater voltages. I'd still plan on running the 12au7's plates at 70v.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 17, 2009, 02:23:53 PM
Finally got around to doing a soundclip: http://www.aronnelson.com/DIYFiles/up/Murder_One.mp3

Signal path:

Squier Telecaster Custom (HB)  >  Murder One (cranked)  >  12" / 8 ohm speaker  >  Shure SM58  >  Event Echo Gina 24 soundcard  >  Wavelab

No other processing.............except when I stomp on the Valvecaster half way through.........you'll know when.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kurtlives on March 02, 2009, 07:08:46 PM
NOTE ^

The 60v you get out of the transformer would be AC, not DC, which, after rectification, would actually give to higher than 60vDC (~ 83vDC). You may want the added voltage, but if you don't you could choose a different transformer.

Determine the HT you want, and then add 5 volts to that to get your target DC voltage (HT + 5v = Vt)

Once you have target voltage, divide it by 1.414 to get your secondary AC voltage you need to be supplied by the transformer (Vsec)

Once you have your secondary AC voltage, use this ratio to determine the transformer you should use.  (120v / 'x') = (Vsec / 12v)  where x is the desired value of the transformer secondary

For example, if you wanted an 78v B+, your Vt would be 83v. This divided by 1.414 would be 60v. Plugged into the equation this would read (120v / 'x') = (60v / 12v)   which when solved would show a 24v secondary. So you would use a 120v to 24v transformer (120v is always the primary).


Zach
Would you get that 78V DC B+ if you wired the 24V side of the transformers to the 120V IEC jack. The 120V winding of the transformer then puts out 78V DC?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 02, 2009, 07:17:21 PM
Here's the start of another Murder One that I'm building for a friend:

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0008-6.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Jered on March 02, 2009, 07:19:18 PM
  Rick, the murder one sounds good and with the valvecaster it gets a great fuzz sound.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 02, 2009, 07:21:31 PM
 Rick, the murder one sounds good and with the valvecaster it gets a great fuzz sound.

Thanks Jered - did you do anything with your nixie PS yet?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 07, 2009, 06:46:23 AM
Another "Murder One (http://www.diystompboxes.com/smfforum/index.php?topic=73222.0)" built for my forum buddy sweetwilly. A much tighter build than my first. It uses a 7327 instead of a 6111, which give a bit more gain. The transformer is a Hammond 1750A, which is their equivalent to the Fender reverb transformer. The PS supplies a few more volts than mine, (more efficient caps perhaps?) so it's a bit louder - damn!

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0010-6.jpg)

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0012-4.jpg)
Title: Power Supply Perf Layout
Post by: frequencycentral on March 07, 2009, 07:43:52 AM
I did a perf layout for the power supply, which you can find here (http://www.diystompboxes.com/smfforum/index.php?topic=74729.0).
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 07, 2009, 11:07:26 AM
(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0014-3.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 08, 2009, 10:07:45 AM
(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0014-3.jpg)

no words!!!

 ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 08, 2009, 10:09:36 AM

no words!!!

 ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D


Did I mention that it lights up in the dark? Wanna see a photo of that too? I'll post one later when it's dark!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 08, 2009, 10:15:23 AM
giggidy giggidy...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 08, 2009, 10:17:46 AM
giggidy giggidy...

.........and I expect you to write a full review on this thread when you've lived with it for a while.  :icon_biggrin:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 08, 2009, 10:21:07 AM
would be a privilege and an honour my friend!  can't wait to begin the testing.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 08, 2009, 02:21:27 PM
(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0001-13.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kurtlives on March 08, 2009, 02:26:09 PM
badass
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Renegadrian on March 08, 2009, 08:18:48 PM
 :icon_eek:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 09, 2009, 06:00:55 AM
badass

:icon_eek:

+1!!!!!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 13, 2009, 07:50:25 AM
I received my Murder One from Rick last night. 

I've only had a chance to try it out with a MacGyvered speaker setup - 2 6ohm desktop speakers in series - but even through this sub-optimal arrangement this thing kicks!  Spent a few hours testing pedals in front of it.  My favourite combo was Gibson Firebird - Ross comp clone - modded Dunlop Fuzz Wah - Pentaboost - Red Llama - EA Trem - Next Analog Delay - Murder One.  Both the fuzz-wah's fuzz and the Red Llama sound awesome through it.  Awesome fuzz and super long sustain into some really sweet harmonic feedback. 

With guitar plugged straight into it you get sweet 60's garage sounds.  "Did someone poke holes in my speakers with a pen?" kind of thing. 

Will provide a more detailed review of the sound when I get to play it through a more efficient, 8 ohm speaker.

The workmanship is top notch - not hard to imagine when you look at some of Rick's other builds - and the layout is such that if tubes need replacement, etc it would be a pretty painless process.

Great work Rick, can't thank you enough!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: ConanB on March 15, 2009, 01:07:43 AM
Finally settled in at my new place and unpacked my submini tubes and went to grab the schem for Murder One but it's no longer up on photobucket, anyone able to send me the current version?

Cheers  8)

Conan.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 21, 2009, 11:51:48 AM
Here's the start of the next one:

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0005.jpg)

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0006-1.jpg)

I've shrunk the layout right down. Just waiting for transformers to arrive to finish this one - and a few more.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 30, 2009, 10:13:03 AM
The latest "Murder One" Submini Tube Guitar Amplifier. This one is already SOLD, I'm building a few more identical if anyone's interested in owning one.

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0009-1.jpg)
(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0010.jpg)
(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0011.jpg)
Title: without words...
Post by: Renegadrian on March 30, 2009, 11:10:06 AM
(http://www.clipartof.com/images/emoticons/xsmall2/469_jaw_dropping.gif) (http://www.clipartof.com/images/emoticons/xsmall2/469_jaw_dropping.gif) (http://www.clipartof.com/images/emoticons/xsmall2/469_jaw_dropping.gif)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tranceracer on March 30, 2009, 02:30:37 PM
Very nice!  Great work RICK!   :D
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: 8bitapocalypse on March 30, 2009, 03:16:44 PM
looks great! how much are you selling these for?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 30, 2009, 03:40:23 PM
Very nice!  Great work RICK!   :D

Thank you!

looks great! how much are you selling these for?

Thanks!

I'm far too much of a gentleman to discuss money in public, PM me if you're interested.  ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 31, 2009, 09:52:49 AM
Yeah, it's pretty un'all, but mine lights up red in the dark! :icon_twisted:

Very nice work Rick!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 31, 2009, 09:53:59 AM
Yeah, it's pretty un'all, but mine lights up red in the dark! :icon_twisted:

Hahahahahaha!!  :icon_mrgreen: Admit it  - you want another one!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 31, 2009, 10:50:11 AM
DESPERATELY!!!

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 31, 2009, 10:59:25 AM
DESPERATELY!!!



Well, maybe I could tempt you with a "Sub Zero"? Or one of the 'other' designs I've been secretly working on...............
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 31, 2009, 11:51:12 AM
SUBZERO me up! 

The "other" designs sound pretty bloody tempting too though!    ;D
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on March 31, 2009, 12:14:13 PM
SUBZERO me up! 

The "other" designs sound pretty bloody tempting too though!    ;D

If I were you, I might wait around to see his Promiscuous Girlfriend :D, that sounds like it should a great little amp. (In case you missed it, his next amp is a little dirt machine that he is tentatively calling Promiscuous Girlfriend, I just like to mess with the title)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sweetwilly on March 31, 2009, 12:39:22 PM
Combine a Promiscuous Girlfriend with a Murder One and you've got life with no chance of parole my friend!

It's the "Ted Bundy" of low-watt amps I'm looking forward to in particular, but will have to wait for Rick to go public with that one!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: stereovoid on March 31, 2009, 05:00:17 PM
rock and roll dudes!!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: stereovoid on April 02, 2009, 12:16:54 PM
hi all, recieved my murder one this morning hot off the bench from rick! it has blown me away! its a beast...and a beautiful one at that! i'll do a bit of a write up once i've had more time to play! did do a little recording though! www.myspace.com/mybandisclub27  The song is reflecting frequency, you have to excuse the bad vocals and mixing...it was a quick job! i used a ten inch 16 ohm blackstar speaker cab. added some reverb from my boss recorder and compressed overall. the guitar is straight into the amp. no bass on it...i don't own one! and the drum machine is very boring! see what ya think! peace, steve.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 02, 2009, 12:34:11 PM
hi all, recieved my murder one this morning hot off the bench from rick! it has blown me away! its a beast...and a beautiful one at that! i'll do a bit of a write up once i've had more time to play! did do a little recording though! www.myspace.com/mybandisclub27  The song is reflecting frequency, you have to excuse the bad vocals and mixing...it was a quick job! i used a ten inch 16 ohm blackstar speaker cab. added some reverb from my boss recorder and compressed overall. the guitar is straight into the amp. no bass on it...i don't own one! and the drum machine is very boring! see what ya think! peace, steve.

Sounds Like it's in good hands Steve, and I'm glad you're enjoying it. I'm glowing with pride!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: stereovoid on April 02, 2009, 06:04:19 PM
and i'm glowing at the fact the tube glows! doh to me but i thought they would both be non glowers like the pentaboost! this amp is great, loving the fact that i can record an all on ten true tube sound at eleven at night! going to be posting some more demoish clips rather than song stuff soon! hats off to you rick!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: spudulike on April 02, 2009, 07:59:44 PM
@Rick,
Where do you get your tubes from ?
UK supplier ?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 03, 2009, 12:33:36 PM
@Rick,
Where do you get your tubes from ?
UK supplier ?

I don't know of any UK suppliers for these tubes, though you will find suppliers in Europe and the USA on Ebay.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: stereovoid on April 04, 2009, 08:17:57 AM
was yust trying the murder one through a 12 inch 4 ohm cab and it sounds killer, also finding that a combination of gain and guitar volume tweaking is making this much more versitle than i first thought, full out heavy rock back to crunchy blues, sweet! loving it!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 17, 2009, 09:43:32 AM
Gut shot of the pre-PCB prototype, for those who are interested:

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0001-7.jpg)

......and a cheesecake shot:

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0014.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on April 17, 2009, 11:54:22 AM
I've never seen such a clean piece of perfboard wiring as that...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 17, 2009, 12:18:47 PM
I've never seen such a clean piece of perfboard wiring as that...

Thanks Brian. I've had practice...........there are eight 100mm x 160mm totally stuffed perfboards in my DIY modular synth. After that little amps and effects are a doddle. The key is a very fine soldering iron tip:

(http://i210.photobucket.com/albums/bb292/frequencycentral/1138197.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: svstee on April 17, 2009, 12:31:30 PM
Gut shot of the pre-PCB prototype, for those who are interested:


Man, I know you would be shooting yourself in the foot a bit here, but if you sold PCBs for this I would buy a couple for sure!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on April 17, 2009, 12:41:28 PM
I actually have a 1/64" tip, but have just never put it on the iron, the current tip works so well, I think I will go till it dies and then use the fine one.  Good to know my joints might actually clean up... :icon_biggrin:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 08, 2009, 10:58:11 AM
Ok after doing some of your other projects, and am really having fun with submini tubes again.

I have the parts on order, but I'm wondering if you could explain what is going on in the Murder One design.

I'm guessing the 6111 is the "preamp" section. Or at least the part that "colors" the sound. And that the 5672 is a clean boost acting as the "power" amp section feeding the transformer? So I could replace the 5672 with a clean boost of my choosing? Is it possible to place a tone stack in here, if so where?

Thanks for all your help!
-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 08, 2009, 11:18:22 AM
Ok after doing some of your other projects, and am really having fun with submini tubes again.

I have the parts on order, but I'm wondering if you could explain what is going on in the Murder One design.

I'm guessing the 6111 is the "preamp" section. Or at least the part that "colors" the sound. And that the 5672 is a clean boost acting as the "power" amp section feeding the transformer? So I could replace the 5672 with a clean boost of my choosing? Is it possible to place a tone stack in here, if so where?

Thanks for all your help!
-Berger

Hi Berger, glad you're having fun!

Yeah, the 6111 is a two stage preamp, the 5672 is the power amp section. The 5672 could be replaced by the 5639 you used in your Pentaboost with a bit of thought. I've breadboarded similar amps using different submini pentodes instead of the 5672, such as 6397 and 5902. If you do use a 5639, you could conside higher plate voltages, at the 5639 handles up to 165 volts, so you could add more stages to the MAX charge pump(if the works, I blew a MAX by adding two extra stages) or consider using the SMPS I used in my Sub Zero amp. TBH, I wouldn't add a tonestack to this, as you'll lose a lot of gain and volume by doing so. However, if you replace the 6111 (gain of 20) with a 6112 (gain of 70), you'll be able to add a tonestack without losing out, as the extra gain of the 6112 makes up for tonestack losses. If it were me, I would add the tonestack after the first triode, before the gain control.

Rick
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 08, 2009, 01:22:14 PM
Thanks for all the info. I have some 5672s coming in, hopefully today, but I'll breadboard it and compare the 5639s as well. I also may play around using some different tubes for the preamp section. Sounds like I understand what you're doing with the setup, which is great....I love learning about this stuff.

I got a couple LT1054CP so I'll use those for the power supply...at least for now.

Thanks for the response!

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 11, 2009, 11:31:31 AM
Another quick question, do you need to use higher voltage capacitors for the other caps in the circuit? 100v? Also cause I still use the usual 1/4 watt resistors?
Just wondering since the voltage is getting pumped higher than the usual 12volts.

thanks!
Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 11, 2009, 11:41:50 AM
Another quick question, do you need to use higher voltage capacitors for the other caps in the circuit? 100v? Also cause I still use the usual 1/4 watt resistors?
Just wondering since the voltage is getting pumped higher than the usual 12volts.

thanks!
Berger

I don't think there's any need to use high voltage caps or anything other than 1/4 watt resistors except for those specified. I've build half a dozen of these, which are all in use, and they all appear to be functioning just fine!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 11, 2009, 11:46:51 AM
Thanks, I've been having fun looking at different "preamp" designs and am really looking to bread boarding this thing up and playing around and seeing what sounds I can get from it.

Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Br4d13y on May 11, 2009, 08:37:27 PM
do you think we could take this thing a step further and add multiple power amp stages too output more volume, but keep a smaller preamp section "ala" an orange?? just throwing some ideas out there
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 12, 2009, 01:53:56 AM
Sounds like fun, it's something I've been meaning to try.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 12, 2009, 08:58:30 AM
A lot of the designs I see are using pentodes for the power amp section. The firefly amp I have(ax84.com) uses a 12au7 for the power amp section. I'm thinking of breadboarding that up as well, to see how it sounds.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 14, 2009, 07:55:26 PM
I've had a number of requests for the layout I used. TBH, I was holding off as I planned to retire to the Bahamas on the strength of Murder One sales, but it looks as if i'll be luck to retire to S@#$%horpe. So here's the perf layout I used for the first few, and the PCB layout I'm now using. Both are obviously tailored to the enclosure layout I use, and also the size of the caps and the two voltage drop resistors, R4 and R5.

(http://i210.photobucket.com/albums/bb292/frequencycentral/MOperf.gif)
(http://i210.photobucket.com/albums/bb292/frequencycentral/MOpcb-1.gif)
(http://i210.photobucket.com/albums/bb292/frequencycentral/MOpnp.gif)

Here's the direct links to the files, as I think Photbucket might resize the PNP

http://dl.getdropbox.com/u/967492/MOperf.gif

http://dl.getdropbox.com/u/967492/MOpcb.gif

http://dl.getdropbox.com/u/967492/MOpnp.gif

Enjoy! It's good to share isn't it?!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 15, 2009, 11:52:48 AM
For anyone who wants a ready made PCB, I've passed the files to John Lyons, his work is very high quality, he can be contacted here:

Email: basicaudiowv@earthlink.net

PM: http://www.diystompboxes.com/smfforum/index.php?action=profile;u=1334
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 15, 2009, 01:41:15 PM
Thanks for making these available  ;D

I'm working on perf now...just waiting for the transformer to show up, so I can finally test this thing!

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 19, 2009, 08:44:42 AM
I tried hooking up my 5639 and I got a farty/slubby sound out of it.

Quote
Hi, you got it running with a 5672 first? How did it sound? The only info I have on the transformer is it's ratios. Did your 5639 amplify but sound farty? I would experiment with with grid 2 resistor (100 ohm in the schematic), try a 33K maybe. Also, you know the cathode resistor/cap you used in Pentaboost, are you doing the same with the amp with the 5639? try playing with those values too. I've tried many different amp ideas on the breadboard with the same transformer, impedence mismatch doesn't seem so crucial to me. Maybe we should discuss this in public on the thread for the benefit of others too......!

It sounds great with the 5672 in place. since its only 5 pins I've been keeping it in the breadboard, so I can go back and hook up to it to make sure things work ok, while trying to work with the 5639.

I'm using the same cathode resistor/cap as before. I've played with the resistor and it helps clena things up a bit, but at a big volume loss. I also changed the grid 2 resistor to a potentiometer and I experience the same deal, of cleanup but volume loss.
I did some reading after I posted and it suggested what you suggested above, of course it was bed time so I haven't gotten to play around with it any more.


Also did you ever experiment with a triode or a twin triode running parallel as the power section?

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 19, 2009, 11:52:37 AM
All I can suggest with the 5639 is just to play about with the cathode resistor/cap values, and the grid 2 value. It might be a trade off between good sound and volume. You might even try directly connecting grid 2 to B+ (is that called triode mode?), though generally it is desirable for the grid to be neagtive to the plate, ie, have a lower voltage presented to it. You could also try directly grounding the cathode. It's hard to harm these subminis, they were designed to stand up to massive abuse!

During Murder One's design I experimented with a parallel triode output section (google the Heavy Watter), and also a single ended arrangement using two 6111 similar to a Pepper Shredder ( http://www.tube-town.net/diy/lov/lov02-peppershredder-eng.html ), but using the final stage as a power amp. The parallel triodes didn't seem to add anything, and I found the sound sweeter and brighter using the 5672. Still worth experimenting with though, your experiences may vary from mine.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 19, 2009, 12:01:15 PM
Thanks! From what I read last night, thats about all I can try at the moment. I'll see if I can play with it tonight, otherwise I won't till next monday(I'll be out of town) if anything that'll give me a lot of time to read up on the subjects.

I'll looked at both of those designs, i'll have to print them out so I can study them over the weekend.

I'll keep this thread posted with what I find out.

Thanks Again!

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 19, 2009, 12:05:08 PM
Cool. You probably already know Valve Wizard, but here it is anyway - a great resource for all things tube, and Merlin is such a nice guy too: http://www.freewebs.com/valvewizard/
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 19, 2009, 01:36:28 PM
I've been printing out the pages and reading them before bed. I've also been using aiken amps tech info pages http://aikenamps.com/TechInfo_2.htm
The combo of the two have really helped me understand whats going on.

Slowly but surely I'll get this stuff figured out.

Thanks!

-Berger


Edit: Just pulled up the heavy watter scheme, and it looks like something I really want to try. I'll have to play with the 12au7 "power amp" sometime. i've been looking for a schematic of a parallel single ended power amp stage and that is it! Thanks!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 28, 2009, 06:11:17 AM
Murder one featured in Guitar Buyer Magazine!

Well, not exactly featured, Murder One owner stereovoid says..........

...i did write a letter to Guitar Buyer about the interesting people i've met that are making interesting stuff...and they printed it!! its in this months mag, and there is a picture of it!



Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 28, 2009, 09:02:45 AM
nice! Congrats!
I'm hopefully going to get time tonight, or next week to work on this some more.

-Aaron
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 28, 2009, 09:11:51 PM
Ok, got to play tonight!
I got it working with the 5639 tube. Normal connections but 1uf to 10uf cap on pin8 and a 1k resistor on pin 8. Changing the cap value changed some of the hum I was getting, and it seemed to affect the tone.
I was running the plate voltage at 60v, I'm sure I can push it farther, just need to make another power charger circuit.

I also change the preamp section to a pentaboost, I like it! I also tried some different triode tubes for the "power" section, Not so great sounds, I'm sure I need to do some biasing there.

I think I'll play with the preamp section, maybe throw a tonestack in there, and then mess with the tridoes for power.

Thanks for all your help!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 29, 2009, 06:59:17 AM
That's cool! One of my early versions of Murder One used a 5672 (ie Pentaboost) as the pre and another 5672 at the power amp, I found a daul triode preamp worked better for me. But you've got a 5639 as the power amp right? I have some 5840 which should be similar enough to the 5639 for me to try this.

If you have any 6112 in stock you can use that in place of the 6111 and add a tonestack without losing gain/volume. The 6112 has a gain of 70 compared to the 6111 gain of 20, so the tonestack losses will be made up for by the extra gain of the 6112.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on May 30, 2009, 09:30:19 PM
I got to play around today.
I traded out the 5639 for a 6BA5 and I like it! It sounds the same but have a lot less current draw on the heaters.

I redid the preamp section as the heavywatter into the 6ba5. I like it! I used 6112s for the 12ax7s.
I tried a bmp tonestack and I was amazed how much of the volume, and thus distortion, was pulled out of the circuit...and it didn't make a good tone control either...I'll have to make something else up.

I'm going to see if I can read up on the heavywatter and see what changes I can make to it tone wise as well.

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: John Lyons on May 30, 2009, 10:27:14 PM

Rick gave me the ok to make some boards for sale.
These are .06 thick, 2oz heavy copper.


(http://www.basicaudio.net/Murder-one-board.jpg)

$15 worldwide, postage included.
Just email me at: basicaudiowv AT earthlink.net
Paypal is best for me but a Money Order is fine.

John



Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: MicFarlow77 on May 30, 2009, 10:31:09 PM

Rick gave me the ok to make some boards for sale.
These are .06 thick, 2oz heavy copper.


(http://www.basicaudio.net/Murder-one-board.jpg)

$15 worldwide, postage included.
Just email me at: basicaudiowv AT earthlink.net
Paypal is best for me but a Money Order is fine.

John


John, your work is just plain awesome!!!!!!!



Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: John Lyons on May 31, 2009, 01:05:17 AM
"I didn't ask for this gift, it was forced upon me..."  :icon_redface:

Well maybe plain but I don't know about awesome.

Too kind!

john
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on June 12, 2009, 09:48:43 AM
I ended up going with the heavy watter with a pentode power amp section

(http://farm4.static.flickr.com/3321/3617850363_b400deee1b.jpg?v=0)

here is a little clip of it too
http://www.youtube.com/watch?v=RBrWUla-QWM
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on June 12, 2009, 01:08:24 PM
Hey Berger, the clips sounds really meaty and chunky, glad you got it built! I'd be interested to see your full schematic.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on June 12, 2009, 01:41:22 PM
the funny deal is that I had my attenuator on so that was only half of the volume. I played it again this morning and it's even more meaty and chunky. BTW no tone control on it.
I'll try to get a schematic up for it. I made a diy layout for it as well.

I combined your charge pump on the board with the amp design. I believe I have the charge pump at ~90vdc with it being in the 80's while under load.

Glad you like it. I'm really glad I built it :)

I'll try to get you guys more info soon.

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on June 12, 2009, 01:46:33 PM
I dig the sound of that--I'll be looking forward to your schematic.

For anyone: where do you guys pick up those hefty power resistors? I generally get my stock from Futurlec/Pedalpartsplus/Smallbear, and I'd really only need to get the high-wattage resistors from a different vendor--I don't have any close-by electronics stores to go to, either--any ideas? Ebay maybe?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on June 12, 2009, 01:53:21 PM
For the big power resistors, If I only need 1-10 I'll usually pick them up on ebay. I did that with the big resistors for the small pentodes that frequency central uses.

Otherwise I've always gotten them from mouser. When I built the Firefly amp I ordered extra 1/2watt 1watt resistors to same on costs...so I have some from there...but I need more :)

So...whats a good piece of software to draw up the schematic? like I said I have a layout, but I think it'd be easier to understand with a schematic..

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jacobyjd on June 12, 2009, 01:56:27 PM
ahh--ok, I refined my search terms a bit and found what I need on Ebay--yeah, 10 or so items is all I'd need-this would be a one-off thing for me :)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on June 12, 2009, 03:09:39 PM
Ok I did this quick in ExpressSCH I believe it is correct. Let me know if you see anything.

The pentode is a 6ba5 it would also work with the 5639 but that has more current draw on the heaters. But they both sound good.

Keep the questions coming if you got them

-Berger

(http://farm3.static.flickr.com/2463/3620347202_71b0a9583c_b.jpg)

link to full size
http://farm3.static.flickr.com/2463/3620347202_71b0a9583c_b_d.jpg (http://farm3.static.flickr.com/2463/3620347202_71b0a9583c_b_d.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on June 15, 2009, 10:20:43 AM
I'm not getting much from the pots in terms of them changing much. it kinda goes from quiet to full on  :icon_razz:
Any ideas on how to get more range from it?

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on June 16, 2009, 08:51:54 AM
Actually I played with it again last night and the knobs work well, so I'd say use those values if you build it.
Oh and the b+ I'm using is between 80 and 90 vdc

-Berger
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: MikeH on June 17, 2009, 02:53:22 PM
Where have you guys found an 18ohm 2 watt resistor?  Mouser doesn't even carry them.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on June 17, 2009, 03:05:05 PM
I used ebay
http://shop.ebay.com/items/?_nkw=18+ohm+2w&_sacat=0&_trksid=p3286.m270.l1313&_odkw=18ohm+2w&_osacat=0

that search turned up some. If you want I can lookup the seller I bought them from, I got 10 and it was pretty reasonable.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on June 17, 2009, 03:12:22 PM
Got mine from Banzai (Germany): http://www.banzaieffects.com/Royal-Ohm-2W-c-1129.html
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: MikeH on June 17, 2009, 04:29:20 PM
Any US suppliers that anyone knows of?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on June 17, 2009, 04:49:29 PM
Any US suppliers that anyone knows of?

You could use a 7806 voltage regulator instead.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: MikeH on June 17, 2009, 04:56:05 PM
Yeah, I didn't know if that had been brought up in this long thread (which I have not completely read) but I was thinking regulation might be a better way to go anyway, especially if I was using a compact layout, and a smallish enclosure with the tubes inside.  I thought heat might become a problem.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on June 17, 2009, 05:18:51 PM
If you check my layout, the two voltage drop resistors sit between the two tubes, so if you have the tubes protruding from the enclosure like mine are, there's good ventilation to dissipate the heat.........and hot resistors do smell so good don't they!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Berger on June 17, 2009, 10:33:54 PM
I used the regulators in mine
(http://farm4.static.flickr.com/3601/3635906663_aae5882e87.jpg)
(http://farm4.static.flickr.com/3377/3636723982_b2d66dc8f0.jpg)
I'm painting my enclosure at moment   :P
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on July 01, 2009, 08:26:01 PM
...
(http://i210.photobucket.com/albums/bb292/frequencycentral/MOpnp.gif)

Here's the direct links to the files, as I think Photbucket might resize the PNP

http://dl.getdropbox.com/u/967492/MOperf.gif

http://dl.getdropbox.com/u/967492/MOpcb.gif

http://dl.getdropbox.com/u/967492/MOpnp.gif

Enjoy! It's good to share isn't it?!

If you don't mind me asking, what are the dimensions to the pnp (lenght & width)? My image software is saying the print size is 16 inches by 9 inches, seems a bit too big.

Thanks.
-Bernard
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 02, 2009, 12:45:16 PM
If you don't mind me asking, what are the dimensions to the pnp (lenght & width)? My image software is saying the print size is 16 inches by 9 inches, seems a bit too big.

Thanks.
-Bernard

John Lyons made me up some boards from the same files I posted here, their dimensions are 68mm x 35mm (2.677" x 1.378").
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on July 02, 2009, 10:12:50 PM
A few more questions if you don't mind again. What size enclosure did you use (metal one)? And in the previous posts looked like there was a build with a plastic enclosure, is there a difference in performance from the plastic to your metal enclosed one (noise wise)? Or enclosure material doesn't matter much for this small amp?

Thanks.
-Bernard
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 03, 2009, 01:14:05 PM
A few more questions if you don't mind again. What size enclosure did you use (metal one)? And in the previous posts looked like there was a build with a plastic enclosure, is there a difference in performance from the plastic to your metal enclosed one (noise wise)? Or enclosure material doesn't matter much for this small amp?

Thanks.
-Bernard

The metal enclosure I used is an Eddystone (subsiduary of Hammond) 110mm x 60mm x 30mm. Is that a 1590B? There's no difference in performance with the plastic cased ones I made versus the metal cased ones. I'm much happier with the mateal case ones though - they look so cool, though it is a tight fit to squeeze everything in!

Title: Grid 1 biasing mod for "Murder One".
Post by: frequencycentral on July 08, 2009, 02:19:58 PM
Once in a while someone comes along and says 'hey, try it this way'. That just happened, a Murder One builder Pm'ed me today, and said he'd read in the 5672 datasheet that grid 1 should be biased at -6.5 volts. He had used an extra 555 based circuit to get the -6.5 volts, and reported that it really improved the tone and clean headroom. So I had to try it!

Well I thought it should be possible to derive the bias voltage from the MAX without adding extra circuitry, so here's my quick and dirty solution:

1. I added a 10uf cap between pins 2 and 4 of the MAX1044 (+ve end at pin 2).
2. I connected pin 5 of the MAX1044 to pin 4 (grid 1) of the 5672, via a 100K resistor.
3. I added a 0.1uf cap between lug 2 of the volume control and pin 4 of the 5672.

How simple is that? The output of the MAX at pin 5 (with the cap now added between pins 2 and 4) is -5.9 volts, that's close enough for jazz. There is now a lot more control with the Gain and Volume knobs, there's a nice chimey clean sound too, but push everything up full and it still honks! Cool!  8)

Thanks to Aldas for this great mod!
Title: Version 4 schematic
Post by: frequencycentral on July 08, 2009, 02:54:46 PM
So here's the latest rev, with the biasing mod:

(http://i210.photobucket.com/albums/bb292/frequencycentral/MurderOneV4.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: doitle on July 08, 2009, 07:56:49 PM
I'm starting to think that I might be able to build the Murder One and am in the planning stages. I have no idea how I will actually assemble it as I just plain old cannot do perf board. :/ I'm terrible. I was thinking I might be able to figure out some tag strip based construction... Not entirely sure about that. Anyhow I was looking at transformers and that Fender Reverb transformer is about 13$ on AES. They've also got a 8W SE Output Transformer for 13$. It's only 5K Ohm primary instead of the 25K of the reverb driver. I'm not sure what the output impedance is of the pentode power stage but I was wondering if that TF might be a better fit.

Another question I had was why you stopped at 80V for your B+? In simulation at least I managed to get a LT1054 pushing 12V up over 100V. Since the 6111 are rated at 150V it should be fine running even higher than you have it but I was wondering why you stopped where you did.

Also lastly what would your suggestions be for a speaker to drive? It's 8 ohm output but considering the power handling is below 1W I am wondering just how small of a speaker would be a good fit for it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 09, 2009, 03:36:13 PM
I'm starting to think that I might be able to build the Murder One and am in the planning stages. I have no idea how I will actually assemble it as I just plain old cannot do perf board. :/ I'm terrible. I was thinking I might be able to figure out some tag strip based construction... Not entirely sure about that. Anyhow I was looking at transformers and that Fender Reverb transformer is about 13$ on AES. They've also got a 8W SE Output Transformer for 13$. It's only 5K Ohm primary instead of the 25K of the reverb driver. I'm not sure what the output impedance is of the pentode power stage but I was wondering if that TF might be a better fit.

Another question I had was why you stopped at 80V for your B+? In simulation at least I managed to get a LT1054 pushing 12V up over 100V. Since the 6111 are rated at 150V it should be fine running even higher than you have it but I was wondering why you stopped where you did.

Also lastly what would your suggestions be for a speaker to drive? It's 8 ohm output but considering the power handling is below 1W I am wondering just how small of a speaker would be a good fit for it.

I always plan my complete build from the ground up befroe I start work. With this project there are a few odd shaped parts, so you really need to be sure of how it's all going to fit together before you start your build. I'm not so sure tag strip would be the way to go - maybe you should work up a vero layout? Or get a PCB from John Lyons, it's pretty easy to add the grid 1 bias mod to the PCB (though not ideal), I'll be doing a new PCB soon, though I have an idea that I should look at biasing the 6111 cathodes first too.

The Fender reverb transformer is a good match to the 5672 pentode because the 5672's load resistance is 20K and the transformers is rated at 22.5K into an 8 ohm speaker. So you'd have an impedance mismatch were you to choose a transformer with a 5K primary.

I stopped at ~80 volts for the B+ as the maximum rating for the 5672 plate voltage is 90 volts. I've got some other submini pentodes with higher maximum plate voltages (5902, 6397, 5840), but it seems to me that any higher a plate voltage and you should be using a SMPS instead of a charge pump - the charge pump in Murder One uses 12 caps and 12 diodes but is still quite compact, to double the plate voltage you'd be doubling the number of caps and diodes, whereas a SMPS does the same job with many fewer components. The original idea behind Murder One was to see if I could build a tube amp using a charge pump for the B+. I feel that the Murder One power supply is totally safe, as opposed to the SMPS I'm using with my Sub Zero (http://www.diystompboxes.com/smfforum/index.php?topic=74786.0) design, which can give you quite a belt if you touch the high voltage parts. Ouch.

I use my Murder One(s) through the 12" 8 Ohm speaker in my Roland Bolt 60 tube combo. I've tried it through 4x12's (I don't own one) and it sounds great too - the better the speaker the better the sound. Through cheap tinny speaker it sounds like crap. I'm planning to build a dedicated speaker cab at some point, maybe 2x12 and get some real nice speaker to put in it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: doitle on July 09, 2009, 07:37:56 PM
Well I feel a bit stupid about my voltage question now... :P I didn't think that the submini pentodes max voltage would be that low.

I may just break down and buy a PCB premade from someone as I dont know how much more confidence I would have in myself working with vero over perfboard.

Also I think I will look into SMPS in the future as it is a neat little concept.

I didn't realize as well that the muder one had enough oomph to power a large speaker cabinet like you've mentioned. I thought it was only .065W... At least I thought I read that somewhere in this thread maybe not. Regardless it actually sounds like a good match for me as I like to play the guitar quiet and even my dad's 5W Vibrachamp is too much for me often.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Scruffie on July 09, 2009, 07:40:26 PM
I might do a vero layout soon if that'd help although it'll probably need a bit of correcting by someone...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ripthorn on July 09, 2009, 09:07:46 PM
I didn't realize as well that the muder one had enough oomph to power a large speaker cabinet like you've mentioned. I thought it was only .065W... At least I thought I read that somewhere in this thread maybe not. Regardless it actually sounds like a good match for me as I like to play the guitar quiet and even my dad's 5W Vibrachamp is too much for me often.

It is only .065W, but how power translates into dB is logarithmic, so .065W has a max volume 30 dB quieter than a 65W amp.  That is very significant, but if your 65W amp cranked maxes at, say, 110 dB, then your .065W amp maxes at 80 dB, which is approximately how loud a typical smoke alarm can beep (or about as loud as someone yelling).  That is why I have a 2W tube amp, about 17dB quieter than a 100W amp (of course all these figures assume into the same speaker, max efficiency of power actually put out by the speaker, etc.).  Hope that helps.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: doitle on July 11, 2009, 06:53:55 PM
I have been trying to come up with a plan for my own submini amplifier similar to the murder one but also I've been trying to look at some other production amplifiers to figure out some of the aspects of design and I cannot seem to find that much in common with say a simple tube amp like an old Fender Champ and the Murder One. This is what I came up with so far and I'm sure it's mostly nonsense but hopefully in time I will learn to turn it from nonsense into something workable. One of the biggest differences I notice is that the Murder One doesn't have cathode resistors for biasing. Are you using the tubes in a zero-bias fashion? I saw in the 6112 (Similar to 6111) datasheet that it could be operated in both fashions. I have mine "configured" for cathode bias right now but the values are largely pointless as I haven't yet figured out the optimal bias point to shoot for and so do not know how to calculate the resistances. Another question is the hookup of your power pentode. It doesn't appear in the schematic to be at all similar to either a full size power pentode like the EL84 or the 6205 I was planning to use.
(http://doitle.markdelano.com/stuff/subminiampwip.jpg)


As for the B+ voltage I was planning to use a dual transformer system a-la the Real Mc Tube to derive a B+ of around 140 Volts. Both tubes I was thinking of using are 165V max tubes so I should be within a safe range and should have plenty of clean headroom (I think...). The two tubes planned are the 6112 and the 6205.

I'm sorry if these are stupid questions, I'm trying to learn what I can of tube design but it is slow going. When I ask my professors if they remember anything or mention that I am attempting to learn about them they almost seem to get mad at me. :( I have found one though who did have some interest (In making Hi-Fi Amp not Guitar Amp) but he is in Poland on vacation still.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 12, 2009, 06:02:35 AM
One of the biggest differences I notice is that the Murder One doesn't have cathode resistors for biasing. Are you using the tubes in a zero-bias fashion? I saw in the 6112 (Similar to 6111) datasheet that it could be operated in both fashions. I have mine "configured" for cathode bias right now but the values are largely pointless as I haven't yet figured out the optimal bias point to shoot for and so do not know how to calculate the resistances.

Yup, no cathode resistors. I was going for maximum gain, and found that this occured without cathode resisitors. I'm revisiting this design at the moment, and am planning to try fixed biasing of the 6111 grids at -9 volts (as per the data sheet), derived from pin 5 of the MAX. I'm still learning, and should in no way be considered an expert! I'm starting to understand biasing a lot better now, and I think fixed biasing as opposed to cathode biasing is the was to go. See this discussion thread regarding grid biasing:  http://www.diystompboxes.com/smfforum/index.php?topic=77741.0

Another question is the hookup of your power pentode. It doesn't appear in the schematic to be at all similar to either a full size power pentode like the EL84 or the 6205 I was planning to use.

The 5672 is not a standard pentode like the 6205. It is 'directly heated', which means that the cathode is internally connected to the heater, and is therefore fixed at the heater voltage which is 1.25 volts. I have some 5840 which (and some 6112), which are similar to 6205 except for the internal connection of the suppressor grid, so I'll be interested to see how your experiments pan out.

I'm sorry if these are stupid questions, I'm trying to learn what I can of tube design but it is slow going.

The questions are fine, keep asking. I'm learning too. Every time I think I've made a leap there's something else that crops up. I'm still asking 'dumb questions' elsewhere on the forum.........!


EDIT: C1 on your schematic looks like it may cut the highs too much.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on July 14, 2009, 04:33:42 AM
Rick (or anyone),

This amp design has caught my interest, but I'm a noob to the amp-building scene--where are the speaker connections located in the schematic?

My best guess would be that it goes on the leads of the transformer, but I'd want to be sure before building :)



Oh yeah sorry. The fender reverb transformer has four wires coming out of it:

Two are for the primary winding - these go to the 5672's plate and B+, as shown in the schematic. I connected the 0 ohm to the plate and the 22500 ohm to B+

Two are the for the secondary winding - these go to the speaker. I connected the 0 ohm to ground and the 8 ohm to the speaker.

This was my first tube amp build too - first time I've used an output transformer too, so I'm assuming I got the poliarity of the transformer correct. Hey, it works!

(http://i210.photobucket.com/albums/bb292/frequencycentral/22921.jpg)


I got this when I ordered a transformer from Triode Electronics. May help with that earlier post from jacobyjd. I still haven't built this amp yet, taking my time acquiring parts, which is good since I see there is a modification to the schematic.

(http://i933.photobucket.com/albums/ad178/bbmonster/diy%20guitar%20pedal/IMAGE0002.jpg)

Sorry for the size of the image, still new to photobucket, thought their resize would've have shrunk it a bit more.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on July 29, 2009, 06:18:14 AM
Hi, I will attempt this amp soon and was reading on some safety/guidelines from various amp sites. Would a standby switch be a good thing for submini tubes? and if it is, where would it go? Also would I need a fuse somewhere? or not needed since using a wall wart and/or the amp is low power?

Also, how hot does the submini tubes get? I was wondering if lining the enclosure holes for the tubes with plastic or a grommet type thingy is a good idea.

Thanks.
-Bernard
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 29, 2009, 06:50:26 AM
Hi Bernard,

I never really considered a standby switch (my VJ doesn't have one for example), if you were to add one it should break the connection between B+ and the tubes' plates, so the heaters would warm up before the plates see any voltage. With the (relatively) low voltages in this amp though, there is probably no need for a standby switch. No need for a fuse either, as the the circuit only sees 12 volts, and the ~80 volts generated by the charge pump is quite safe to touch without so much as a minor shock. The 6111 gets quite warm, as do the two voltage drop resistors, but the 5672 doesn't really get too warm at all. 

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on August 01, 2009, 10:36:31 PM
Just wondering if I got mine working properly. I perfed the MO v4 and have it connected to a Marshall MG15 (disconnected the MG amp and have wires running out the back to connect to the MO. I barely get any audio till the gain is past about halfway and the volume on max. When I do max the gain and volume then the audio is just about or a little over normal talking volume. Could the speaker I just have it connected to not be the the right ohms (or just suck)? I couldn't find out how much ohms speaker is and there is no informational label on the speaker itself.

Thank you.
-Bernard
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 02, 2009, 05:43:51 AM
A good quality speaker will really help. I've been having a lot of fun with my MO recently through the 8" 16 ohm speaker of my VJ. I've been running a BM into the MO. The thing definately rawks - loud enough to get compaint of 'turn it down!' from my GF. I pretty much always run the gain and volume maxed, or nearly maxed. Think of MO as an 'everything set to 10' amp which won't damage your hearing.

I have tried MO through a crappy 12" 8 ohm speaker from an old organ, and it's really quiet. The same with cheap computer speakers. I guess the speaker it half of everything with amps.

This week I'm going to try negative biasing the preamp stages (I suspect I'll need to add cathode resistors too) to see if I can squeeze more clean volume out of it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on August 02, 2009, 06:16:57 AM
Thanks. I really like the sound of the amp as it is through my crappy MG. I was just making sure i built the MO correct. I haven't had the chance to play with low power amps (excluding ruby which i just use with headphones), so I'm unfamiliar with what the volume should be or the range of usefulness on the pots. Now the hard part of putting it in an enclosure and making it look nice.

Thanks again.
-Bernard
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 02, 2009, 06:34:45 AM
By the way - did you check the output of the charge pump with a DMM to make sure you're getting ~80 volts? Also, try it with headphones, you be able to dial back the controls quite a bit and also get a wider range of clean tones.

As for the range of usefulness of the pots when driving speakers, the negative bias mod has improved this, and I'm hoping to improve it further with negative biased preamp mods - but the best sounds are with everything maxed or almost maxed.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on August 02, 2009, 07:17:32 AM
By the way - did you check the output of the charge pump with a DMM to make sure you're getting ~80 volts? Also, try it with headphones, you be able to dial back the controls quite a bit and also get a wider range of clean tones.

As for the range of usefulness of the pots when driving speakers, the negative bias mod has improved this, and I'm hoping to improve it further with negative biased preamp mods - but the best sounds are with everything maxed or almost maxed.

Yep, built the charge pump first and made sure it worked, reading 77 volts. Habit I have being a programmer of "code a little, test a little".  I am using a 12v 1000ma Linksys adapter that is outputting 16v into a 12v regulator that powers the TC1044. And yes, I like using the MO with all the knobs maxed or near max.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 02, 2009, 07:19:50 AM
And yes, I like using the MO with all the knobs maxed or near max.

 ;D  8)  ;D  8)  ;D  8)  :icon_mrgreen:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Renegadrian on August 02, 2009, 06:26:04 PM
ALL MEN PLAY ON TEN!!!  :icon_twisted:
Title: Power amp pentodes in parallel.
Post by: frequencycentral on August 03, 2009, 01:46:32 PM
Got this back on the breadboard today, mostly to try negative biasing the preamp (which didn't work for me) and to try some different pentodes.

One experiment I did was to use two 5672's in parallel (but each having it's own voltage drop resistor for the heater) for the power amp - louder and ballsier. I've seen this done in 'proper' big amps, so I though I'd try it too. Well, it works with two, so why not three or four?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on August 04, 2009, 07:01:40 AM
A question on the bias mod. Is it possible to stick a switch to get back to your original design? Could I just stick an SPST to disconnect the bias or would I need a DPDT to bypass the .1 capacitor after the volume pot along with disconnecting the bias connection? I would try this out but currently using the board to mount the standoffs in the enclosure so unable cut the connections and experiment right now till the epoxy hardens.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 04, 2009, 01:38:36 PM
A question on the bias mod. Is it possible to stick a switch to get back to your original design? Could I just stick an SPST to disconnect the bias or would I need a DPDT to bypass the .1 capacitor after the volume pot along with disconnecting the bias connection? I would try this out but currently using the board to mount the standoffs in the enclosure so unable cut the connections and experiment right now till the epoxy hardens.

Should be fine to do that. You can just use a SPST to disconnect the negative bias, as the volume pot would then become the bias. I don't think you would need to bypass the 0.1 cap. I did that on the breadboard yesterday and it seemed ok to me.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on August 07, 2009, 06:28:39 PM
Wondering if you could help with a slight problem I have. I added the SPST switch to cut off the bias mod to get back to your original design for a more distorted sound. The problem I am having is that when I cut the bias, sound is good for a bit then starts to get really flubbery (or gated is probably the better term) after a few seconds when strumming chords. If I rest a bit, then the chords sound good again for a bit before flubbery again.  When I have the bias on, no problems at all, sounds awesome. Any suggestions that I could do?

Thanks.
-Bernard
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 08, 2009, 07:12:56 AM
Ok, I think whats happening is that the grid is basically unbiased then, because the cap between the volume and the grid is blocking the volume from biasing the grid. So maybe you need to either bypass the cap when ground biasing (as you suggested earlier), or use a DPDT instead of an SPST with the second pole referenced to ground via a 1M resistor. Hey - I'm glad you think it sounds awesome though!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on August 09, 2009, 05:49:43 PM
Thanks, bypassing the cap did the trick.
-Bernard
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 09, 2009, 06:13:33 PM
Could I just stick an SPST to disconnect the bias or would I need a DPDT to bypass the .1 capacitor after the volume pot along with disconnecting the bias connection?

Thanks, bypassing the cap did the trick.
-Bernard

You were right then! How are you finding the two different modes now?



EDIT: If anyone want's a frequencycentral prototype, the original Murder One is for sale: http://www.diystompboxes.com/smfforum/index.php?topic=78320.0
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bbmonster on August 09, 2009, 08:28:26 PM
I'm liking it. It's like how you mentioned before, the bias provides a cleaner sound and the original a more dirty sound. There is enough difference that I'm keeping the switch on.

I was just guessing on bypassing the cap, I have very little understanding of tube amps right now. I'm more of have little understanding of it, build it for even more understanding, if the build doesn't work is even better because you can learn more kind of guy.

Thanks again. I look forward to attempting more of your projects in the future.
-Bernard
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 09, 2009, 08:36:17 PM
Interesting. I originally saw the grid bias mod as an improvement which superceded the original, but now it seems it should really be a stock switchable option. Maybe I should modify the schematic to that effect.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Taylor on August 09, 2009, 09:15:39 PM
Could anyone compare the sound of this amp to something like a Valve Junior? I have a 100w tube amp (I play bass) but I'd like something I can get to distort at lower volumes. Was thinking about getting a VJ, but if I can build something (without having to fool with high voltage) that would be better. Of course, I realize this amp will have less volume than VJ.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 09, 2009, 09:22:25 PM
I have a VJ. Wouldn't dare max it at home. I have the volume set at 10 o'clock generally, with pedals providing the dirt. Murder One is comparable at it's maximum volume, a bit more if you push it with pedals. But "Superfly" (http://www.diystompboxes.com/smfforum/index.php?topic=78302.0) with a BM pushing it is anti-social.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Renegadrian on September 25, 2009, 09:00:00 PM
It seems that our good  pal here Rick is getting quite a lot of attentions!
http://www.jedistar.com/low_watt_amps_2.htm
Hey, I can say I know him!!!  :icon_wink:
Title: Version 5 Schematic
Post by: frequencycentral on December 27, 2009, 10:56:34 AM
Quote from: panterafanatic
I have a question with the biasing conversation that you and bbmonster had, which cap do you bypass when wanting a little more grit from the amp?

Here's the schematic for the version I'm building nowadays, with the biasing switch implemented:

(http://i210.photobucket.com/albums/bb292/frequencycentral/MurderOneV5.jpg)

The perf and PCB layouts earlier in this thread are based one the version 3 schematic, I haven't updated the layout artwork yet - I build these onto perf nowadays (as people seem to value my perf builds), so I kind have the version 5 layout on my head. Do people want updated layouts?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: panterafanatic on December 27, 2009, 05:16:36 PM
it's because your perf work is amazing. would the switching make noise when changing the bias point or should i shut it off before switching how it is biased?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on December 27, 2009, 08:07:30 PM
it's because your perf work is amazing.

Thanks!

would the switching make noise when changing the bias point or should i shut it off before switching how it is biased?

The switching makes a little click, it's not a problem to flick the switch with the amp turned on.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Custard on January 01, 2010, 06:56:27 PM
Hi, this project looks pretty good and I'm going to give it a go, but still waiting (bad time of the year to order stuff) on a few parts.
An updated layout would be greatly appreciated.

Cheers,
Rob
Title: Re: Power amp pentodes in parallel.
Post by: yesitsdrew5310 on January 04, 2010, 09:56:03 PM
One experiment I did was to use two 5672's in parallel (but each having it's own voltage drop resistor for the heater) for the power amp - louder and ballsier

Rick, I love the design you have here.  I want to use some of the ideas in my amp that I am currently working on.  I was using an LM380 (2.5W output amp IC) with a tube preamp section.  But I am intrigued with using a 5672 in the output side of things.
My question is when you were putting the two 5672's in parallel, did the values on the resistors with the bias switch change at all?
Last question, when you put the two tubes in parallel I know it cuts the resistance in half, in this case is the Fender Reverb Transformer 22921 still applicable?

Thanks for your time and insight!


Cheers,
Drew Brashler
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 05, 2010, 08:02:03 PM
An updated layout would be greatly appreciated.

On it's way soon......... ;)

My question is when you were putting the two 5672's in parallel, did the values on the resistors with the bias switch change at all?
Last question, when you put the two tubes in parallel I know it cuts the resistance in half, in this case is the Fender Reverb Transformer 22921 still applicable?

As I remember I just plugged a second 5672 into the breadboard, just isolated pin 3 for seperate heater supply. I didn't experiment with it much, but the biasing switch resistors wouldn't need to change I don't think. You're right, I think it does half the resistance, it still sounded good through Fender Reverb Transformer. I my experience you can get away with some quite extreme impedance mismatch.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: dimi3 on February 09, 2010, 05:18:01 PM
I been reading the whole thread regarding this amp, together with superfly :), Rick I know you are buisy testing new stuff and everyday work, but is there any chance to get version 5 layout posted? please?.

I hope that I can join the murder family soon :).

Keep up the good work.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gigyas on February 18, 2010, 02:45:25 PM
Hi all, this is my first post here, so please bear with me.
I built a Murder One using revision 5 of the schematic, minus the bias switch, just used the 100K resistor over to pin 5 on the 1044. It sounds fantastic except for one problem: it produces a soft hum at about 17KHz.  So I was wondering if anyone else had run into this, or if you guys had any ideas as to how to fix it.

Thanks in advance for the help.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 18, 2010, 03:06:44 PM
17KHz

........is towards the upper limit of human hearing. So it's a high pitched whine rather than a hum? If that's the case it could be that you haven't implemented the boost feature of the MAX1044, ie you need to connect pin 1 to +ve.

......and welcome to the forum, and congrats on your build - we want to see it!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gigyas on February 18, 2010, 06:50:27 PM
Well, whine is just a faster hum, its mostly kind of the same.  I got the number off my o'scope.  So, its good to know that I can still hear up that high, but it gets pretty aggravating.  Maybe I just need to listen to my music really loud for the next couple of weeks, haha.  I am actually using the TC1044, and I do have the boost implemented, verified with the 'scope.  So, I probably need to just sit down with the 'scope and check EVERYTHING, but it was easier to ask you guys first.  I'll let you all know what I find.
Thanks for the welcome.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: therecordingart on February 19, 2010, 01:21:32 PM
This Hammond xfr will work in place of the one from Triode right?

http://www.hammondmfg.com/pdf/EDB1750A.pdf
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 19, 2010, 01:29:17 PM
This Hammond xfr will work in place of the one from Triode right?

http://www.hammondmfg.com/pdf/EDB1750A.pdf

The Hammond 1750A is the one I use.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: therecordingart on February 19, 2010, 01:31:10 PM
Awesome! I appreciate  the work you've put into this, and making it available. Thank you!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 19, 2010, 01:53:15 PM
Awesome! I appreciate  the work you've put into this, and making it available. Thank you!

Nice that people are enjoying them! stereovoid, who I built the first silver one for, has just commissioned me to make an uber Murder One which will include a switchable SHO boost, Vibracaster (http://www.diystompboxes.com/smfforum/index.php?topic=70160.0) style tremolo, BM tonestack, pre out, and a dummy load on the speaker socket.

Here's my last couple:

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0017.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: therecordingart on February 19, 2010, 01:58:46 PM
Awesome! I need to find a source for those "U" shaped bars in the United States. Any ideas?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: fancydirt on February 19, 2010, 02:26:57 PM
They're available relatively cheap through Home Depot (http://www.homedepot.com/h_d1/N-5yc1vZ66xgq/R-202021145/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053).  Ships FREE with $249.00 Order! 
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: therecordingart on February 19, 2010, 02:27:47 PM
They're available relatively cheap through Home Depot (http://www.homedepot.com/h_d1/N-5yc1vZ66xgq/R-202021145/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053).  Ships FREE with $249.00 Order! 

Much thanks, chief!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gigyas on February 22, 2010, 07:07:47 PM
Hi again. I said I would follow up when I figured out where the whine was coming from.
Turns out it comes from biasing the grid of the 5672 using pin 5 of the MAX1044 (although I am using the Microchip TC1044).
So, switching the biasing over to the 1M resistor to ground gets rid of the whine (I initially built mine without the biasing switching option).
Anyway, here are a couple pictures of my unfinished build, still need to decide on how to finish the box.
(http://img714.imageshack.us/img714/2609/m12web.th.png) (http://img714.imageshack.us/i/m12web.png/)
And the gut shot:
(http://img51.imageshack.us/img51/5572/m11web.th.png) (http://img51.imageshack.us/i/m11web.png/)
Thanks for the great design Rick, I really like it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: therecordingart on February 28, 2010, 04:04:08 PM
I'm looking at the newest schematic revision and the PCB layout that was for a prior revision, but I'm having a hard time figuring out the big differences. What is different in the newest schem (other than selectable bias)?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: PedroTejada on March 06, 2010, 12:40:45 PM
I'm definitely in love with this project!  :icon_eek:

Is the latest Schem 100% trustable?

I have a 1x12 cab around my basement, it should be perfect. I have to build something to leave in my office for the next month, and this project seems to be perfect. Also a warm up for my SLO project (I have all parts except the transformers for about 3 years, but didn't started it yet  :o)

I'm going to try to route something this afternoon on Eagle!

Thanks for all the info posted here :D
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 06, 2010, 12:50:23 PM
Is the latest Schem 100% trustable?

Yep, I've built many. I just spent the afternoon drilling and sanding enclosures and applying decals for the next half dozen.  ;D
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: PedroTejada on March 06, 2010, 02:33:16 PM
Cool! And thanks for the fast reply!

I couldn't find those tubes on Eagle lbrs around the net, so I'm going to solder the sockets off board... To be honest I don't really like on board tubes...

I hope to post something tonight!!!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: max30 on March 09, 2010, 05:05:57 PM
tube sockets for subminis are hard to find and not needed in practice, use IC sockets instead you have this in eagle, mirror them to soldering side and you have a nice layout.

I did something simmilar with other great Rick's submini desing "superfly", didnt finish the board yet, since I need to add SMPS on the same board and get them made. There is a really good already available SMPS with eagle files available here: http://www.desmith.net/NMdS/Electronics/NixiePSU.html

I hope that I will be able to finish it soon.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: criszou on March 27, 2010, 11:36:49 AM
Hi, I go to my local store looking for sub tube 6111, but the store only have JAN-6111W. Is this tube 6111W is same as 6111? I ask to store's owner, but he doesn't know.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 27, 2010, 12:14:45 PM
Hi, I go to my local store looking for sub tube 6111, but the store only have JAN-6111W. Is this tube 6111W is same as 6111? I ask to store's owner, but he doesn't know.

Wow, you can get 6111 at your local store - lucky you! I have to get my 6111 shipped across the Atlantic!

JAN-6111W is just fine. In fact better. JAN = Joint Army Navy, higher quality.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 02, 2010, 12:18:18 AM
Hey Rick, thanks for making this available to us!

I'm still very new to all this, but I am going to give your amp a shot--love the tone, love the look, love it.  Parts are starting to arrive.

I was hoping you could point me to a diagram or site that would show how to do the offboard wiring for this.  Google turned up nothing, and didn't see anything on wiring the jacks and such within the thread.

Also, how hard would it be to implement a headphone out?  And, although this might sound dumb, would that negate the need to hook the amp up to a cab?  I've always just used combos.

Thanks!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: phector2004 on April 02, 2010, 01:00:08 AM
that would indeed let you use it without a cab. In terms of implementing it, i'm guessing you'd need to have a different transformer and a separate output or a switch to change between speaker out and headphone out modes... but don't listen to me i'm still pretty clueless when it comes to amps!!

What I do know is it won't sound remotely as good through headphones as it would a small cab. you could also salvage some old computer speakers and use those in place of an ordinary guitar speaker, but don't expect them to spew out any magic and unicorns.  ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 02, 2010, 06:09:46 AM
There isn't a wiring diagram anywhere, I kinda assumed that pedal builders would know where everything goes. I'll see what I can do though.

I have run switchable mono/stereo headphones (in mono mode) direct from the Murder One's speaker out socket with no modifications, sure I mentioned it before, it does clean up considerably driving headphones. And no need to hook up a cab.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 02, 2010, 01:42:33 PM
There isn't a wiring diagram anywhere, I kinda assumed that pedal builders would know where everything goes. I'll see what I can do though.

Thanks!  If it is the same method of wiring as wiring a box as true-bypass, I got that....wired....so to speak.  But the lack of footswitch, addition of a transformer and it's different taps, uncertainty of whether the jacks are mono or stereo (or one of each), etc has me scratching my head a bit.  Again, still very new to pedal building, let alone building an amp as well.

I have run switchable mono/stereo headphones (in mono mode) direct from the Murder One's speaker out socket with no modifications, sure I mentioned it before, it does clean up considerably driving headphones. And no need to hook up a cab.

I thought you said something about it, but I've read each page on this thread a couple times and couldn't find it again, so thought it might just be my imagination.  Thanks for clarifying!  Did you get any results while they were in stereo-mode, or is that just a no-go?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: criszou on April 04, 2010, 09:02:00 AM
Hi, I go to my local store looking for sub tube 6111, but the store only have JAN-6111W. Is this tube 6111W is same as 6111? I ask to store's owner, but he doesn't know.

Wow, you can get 6111 at your local store - lucky you! I have to get my 6111 shipped across the Atlantic!

JAN-6111W is just fine. In fact better. JAN = Joint Army Navy, higher quality.

but only 6111 and 6021, but if I want to build your tube bonanza schematic, some part, not only tube, I have to shipped them across Pasific  :icon_smile:
Thank you Rick...I'll try JAN-6111W.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 07, 2010, 07:55:29 PM
Hey Rick, I was getting ready to build v5 with slight modifications to the perf layout you provided for v3, and noticed the 100uf cap, but it isn't on either schematic.  Should that 100uf cap be there, and does the voltage rating need to be 100v like the 10uf caps?  I'm assuming so because of it's proximity to the PS (and Im also assuming that it is a part of the PS).  Also, what is it's purpose?  I want to say power filtering, but since I know nothing about this stuff, that's just a guess.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 08, 2010, 05:20:34 PM
That cap is just for stability of the 12v input. It only needs to be rated somewhere above 12v, so 16v would do. I tend to just use 10uF 100v cos I buy them in bulk, but any large value will do.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 08, 2010, 08:26:13 PM
Very cool--can't wait to fire this up!  I'm assembling the board right now.  Still a little confused about the transformer wiring, but i guess we'll see what happens :icon_lol:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 09, 2010, 05:35:19 AM
I use Hammond 1750A transformers, wired up thus:


(http://i210.photobucket.com/albums/bb292/frequencycentral/22921.jpg)

The red and blue I just solder onto the copper side of the perf thus:

(http://i210.photobucket.com/albums/bb292/frequencycentral/000_0001-7.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 10, 2010, 08:19:23 PM
Thanks again Rick!  I saw that earlier, but my trouble lies with the tranny I ordered and how the wires are oriented--unless of course there is a uniform color code, in which case I guess I should be fine.  That, and although I think I sort of know what to do with the offboard stuff, admittedly I can't say I do with complete certainty.

Perhaps to save you a bit of time, I think I have the changes for the v5 from the perf layout posted earlier.  Unfortunately, I don't have access to DIYLayout ATM, so it is in text-form.  Please let me know if I made a mistake, but if I'm right, it would look like:

Trace from pin4 of IC1 to perf hole d2, from d2 to d4, d4 to c4, c4 to c5 which is the negative end of the new 10uf cap, positive of that cap being b5; then from c5 to c6, then jumpering from c6 to f6.
The two new bias resistors could go on j6 and k6, and k7 and l7, respectively.  With either an additional row to the perfboard, or via jumpers, go from pin5 of IC1 to the end of the 100k resistor and the 1m resistor could be jumpered anywhere along the ground wire (say, f23 for example).  Then those remaining leads would be wired to the outside lugs of the switch.
The new .1uf would then sit at m22 to m-whatever, which would then connect to the center lug of the switch.

Sorry if that was a total mindbender and/or totally wrong.  Figured other first-timers might benefit from a fellow noob's observations while also getting another pair of eyes to look over what I think might be going on. Or at least get a good laugh. 
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 10, 2010, 08:24:21 PM
Trace from pin4 of IC1 to perf hole d2, from d2 to d4, d4 to c4, c4 to c5 which is the negative end of the new 10uf cap, positive of that cap being b5; then from c5 to c6, then jumpering from c6 to f6.
The two new bias resistors could go on j6 and k6, and k7 and l7, respectively.  With either an additional row to the perfboard, or via jumpers, go from pin5 of IC1 to the end of the 100k resistor and the 1m resistor could be jumpered anywhere along the ground wire (say, f23 for example).  Then those remaining leads would be wired to the outside lugs of the switch.
The new .1uf would then sit at m22 to m-whatever, which would then connect to the center lug of the switch.

Checkmate in 5 moves - amazing!  ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 10, 2010, 08:34:34 PM
Trace from pin4 of IC1 to perf hole d2, from d2 to d4, d4 to c4, c4 to c5 which is the negative end of the new 10uf cap, positive of that cap being b5; then from c5 to c6, then jumpering from c6 to f6.
The two new bias resistors could go on j6 and k6, and k7 and l7, respectively.  With either an additional row to the perfboard, or via jumpers, go from pin5 of IC1 to the end of the 100k resistor and the 1m resistor could be jumpered anywhere along the ground wire (say, f23 for example).  Then those remaining leads would be wired to the outside lugs of the switch.
The new .1uf would then sit at m22 to m-whatever, which would then connect to the center lug of the switch.

Checkmate in 5 moves - amazing!  ;)

Thanks Rick!  I learned more than I thought from this project, and I thought I was going to learn a lot in the first place, and now I'm completely addicted to these little monsters, and can't wait to see if I can make some designs myself!  This taught me an absolute boatload about both amp and stompbox design, building, and theory--all while in a safe context and with an awesome result for my efforts--assuming I don't fudge up the offboard and tranny. :P

Thanks again mate! You're the champ!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 11, 2010, 09:35:03 AM
^^^

Ah, no, I meant that it totally confused me (being a visual learner) and reminded me of chess moves, or battleships.

Anyway, here's a layout for the Version 5 schematic, it adds the bias switch as well as a 1N4007 across the power rails for a bit of polarity protection. It's one row and one column larger than the original layout. If anyone wants to make some up and send them to me for 'evalualtion' I'd be pleased as punch!

(http://i210.photobucket.com/albums/bb292/frequencycentral/MOV5PCB.gif)
(http://i210.photobucket.com/albums/bb292/frequencycentral/MOV5PnP.gif)



Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 11, 2010, 12:53:33 PM
^^^

Ah, no, I meant that it totally confused me (being a visual learner) and reminded me of chess moves, or battleships.

Anyway, here's a layout for the Version 5 schematic, it adds the bias switch as well as a 1N4007 across the power rails for a bit of polarity protection.

Oh...well, the good news is that mine doesn't look that far off from yours--just sloppier soldering and peculiar placement on my end.

For the polarity protection diode, would a 1n4001 suffice?

Regardless, I still stand by my "you're the champ" comment.  :icon_wink:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 11, 2010, 02:38:27 PM
For the polarity protection diode, would a 1n4001 suffice?

Should be fine. You may not need it if you don't make dumb mistake. But as I sell these I figure it's best to have some protection.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 12, 2010, 01:05:18 PM
For the polarity protection diode, would a 1n4001 suffice?

Should be fine. You may not need it if you don't make dumb mistake. But as I sell these I figure it's best to have some protection.

Meh--better safe than sorry I suppose.  Should have this whipped together later today--I'll let ya know how it turns out. 
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: dellamorte on April 13, 2010, 09:45:46 AM
would it be possible to use a murder one to drive a reverb tank rather than a speaker like a fender outboard reverb?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 13, 2010, 02:55:18 PM
would it be possible to use a murder one to drive a reverb tank rather than a speaker like a fender outboard reverb?

Maybe - try it! You'd want a gain recovery stage after the reverb tank. Maybe you could screw around with the basic circuit but use the first triode stage of MO for that instead of using it to drive the second triode, so the topology would be triode > pentode > OT > reverb tank > triode. Tell us if it works.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 16, 2010, 10:43:36 AM
Would a 12v 1A regulated wallwarr work to power it?  I seem to remember from somewhere that they could be rated higher than necessary, but not lower?  Also it is what the dude at one of the local shops suggested since they didn't have a 500ma.  I just want to double check to make sure nothing is going to explode or anything before I try using it.

Thanks!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 16, 2010, 01:34:42 PM
Yup 12v / 1A regulated is fine, the circuit will just draw as much as it needs. I'd steer clear of switch mode though, never tried one but they may cause heterodyning (whining) in conjuction with the charge pump's HFO.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 17, 2010, 01:06:21 PM
Yup 12v / 1A regulated is fine, the circuit will just draw as much as it needs. I'd steer clear of switch mode though, never tried one but they may cause heterodyning (whining) in conjuction with the charge pump's HFO.

Well, guess I'm really gonna have to bank on that "may" part.

What is the name of a kind that wouldn't have that problem?  Or a type you would suggest?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 17, 2010, 02:11:42 PM
Yup 12v / 1A regulated is fine, the circuit will just draw as much as it needs. I'd steer clear of switch mode though, never tried one but they may cause heterodyning (whining) in conjuction with the charge pump's HFO.

Well, guess I'm really gonna have to bank on that "may" part.

What is the name of a kind that wouldn't have that problem?  Or a type you would suggest?

I'm in the UK, dunno where you are? FWIW I find these are perfect: http://www.maplin.co.uk/Module.aspx?ModuleNo=32746 ie not switch mode, just a transformer, a few caps and a voltage regulator inside.

Hmm, maybe I do recall someone somewhere using a MO with a switch mode without issues. I really should buy one to find out for sure...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: dimi3 on April 25, 2010, 05:42:56 AM
V5 layout yees :) thanks Rick, I will put this together, I have a few questions before I start.

I will be ordering parts at banzai, except the tubes that I have.

What is the correct spacing of electrolytic caps? 2,5mm should be ok for latest PCB posted in layout?
What kind of metalfilm caps are u using? the 0,1mf ones?
Banzai doesent have Hammond OT but this: http://www.banzaimusic.com/3.5-Watt-Output-Transformer.html, did you use this one on your first builds? or I should go for Hammond?

I have the power tubes already and preamp tubes, but 6112 not 6111, it has bigger mu (70) compared to 6111 (20) will this work or I will lose all clean headroom becouse of more gain?

Thanks for the help.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 25, 2010, 06:16:52 AM
That transformer is good for this build. Banzai also sell the electro caps: http://www.banzaimusic.com/10uF-100V-Radial.html It's a tight squeeze fitting them, you'll work it out! They stock the two voltage drop resistors too.

The 0.1uF I use are: http://www.rapidonline.com/sku.aspx?tier1=Electronic+Components&tier2=Capacitors&tier3=Ceramic&tier4=Radial+multilayer+ceramic+capacitors&moduleno62498&catref=08-0270

I've used 6112 a couple of times in Murder Ones, they work fine and give more crunch. The Most fun you can have is to use SIL strip as sockets and try 6111, 6021 and 6112.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tgorman on April 25, 2010, 06:13:43 PM
I have been following this post for a while, I finally assembled my build of Murder one today. It was my second build not using a kit. Unfortunately I am getting no sound out of it. Got a bit of checking to do to get it going. Thanks Rick for making this available for others to build. I can't wait to get it going and try it out. I guess I should check the voltages on the ICs and go from there. I already double checked the off board wiring and took a look for solder bridges and so far it looks good. Here is a shot of the outside, I could put up a gut shot if anyone is interested.

(http://i878.photobucket.com/albums/ab344/toddgorman/P4250019.jpg)



Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 25, 2010, 06:35:45 PM
^^^

Looks excellent! But the pentode looks like a 5678 not a 5672, IIR the filament connections are reversed ie pin 3 = F-, S, G3; pin 5= F+, S, G3. I'm not sure if that makes any difference in practice but it may , just may, be the issue. If that is a 5678 I'm not sure how far else it's spec varies from 5672.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tgorman on April 25, 2010, 08:30:20 PM
Yep it's a 5678. Not what I ordered but that's what I got. I will try replacing it with the proper tube. Thanks for the tip! I cant believe I never even checked it before I put it in. Glad I used sockets. By the way how could you tell just from the photo? Sorry I'm a bit of a noob.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 25, 2010, 09:07:53 PM
By the way how could you tell just from the photo?

Damn this x-ray vision! Actually 5678 are grey like yours, while 5672 are clear glass. I have plenty of 5672 if you get stuck.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tgorman on April 25, 2010, 09:18:00 PM
X-Ray vision, wish I had that! Told you I was a noob. I have some of the 5672s on their way, thanks for the offer though. By the way my first non kit build way your Promiscuous Girlfriend. It's my favorite overdrive! That one worked right out of the box. Thanks for the help, God knows I need it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 25, 2010, 09:21:27 PM
By the way my first non kit build way your Promiscuous Girlfriend. It's my favorite overdrive! That one worked right out of the box.

Cool! Post some photos in the Promiscuous Girlfriend thread! And we wanna see guts of the Murder One too....
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tgorman on April 25, 2010, 09:36:57 PM
You got it. Look for them tomorrow, its off to bed now so that I can go to work tomorrow to make money to pay for parts.
Thanks again for the help!!!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tgorman on April 26, 2010, 06:45:25 PM
Okay you asked for it, here it is a gut shot of my Murder One build. Please be gentle it was only my second time.

(http://i878.photobucket.com/albums/ab344/toddgorman/MurderOneGuts.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Plan B on April 28, 2010, 04:46:51 PM
Shit!  I got the same exact tube!  Let me guess, small bear and made by raytheon?  Thanks for catching this--I would've pulled my hair out and probably smashed it with a hammer.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tgorman on April 28, 2010, 06:59:15 PM
Well I don't want to bad mouth them, but yes. They also sent me a free one when I brought it to their attention. I have always had very good service from them.

I have not yet received my new tubes yet so I still can not confirm that it is what is wrong with the one I made. There a lot of other things I could have done wrong along the way. I only just started doing this recently. I only even got a soldering iron so I could put new pickups in my guitar so I don't have a huge knowledge base to work from. I am however enjoying the learning process very much.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: mydementia on May 14, 2010, 03:23:27 PM
It's ALIVE!!
What a fun little amp build!  Reminds my of my 30V Sophtie project (http://dbx-fx.webs.com/30v.htm (http://dbx-fx.webs.com/30v.htm)) only about 1/4 the volume!  
Now to incorporate booster, trem, and all the other snazzy mods - then box it up...
Thanks for the great project Rick!!
The V5 PCB works just fine in case anyone was wondering.
EDIT - looks like the gallery here is having fits with my image... let's try this one...
(http://dbx-fx.webs.com/MurderOneAMP_%20012_Small.JPG)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 14, 2010, 03:37:33 PM
^^^ No pics?

I just finished a new 'modder's delight' layout which includes cathode resistors and bypass caps as well as grid stoppers. Anyone interested?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tgorman on May 15, 2010, 06:11:07 PM
Bring it on!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: dimi3 on May 31, 2010, 06:47:48 AM
^^^ No pics?

I just finished a new 'modder's delight' layout which includes cathode resistors and bypass caps as well as grid stoppers. Anyone interested?

Any news on this one? I finished first MO and its great, I still have some tubes left, and want to try another one with fancy enclosure and everything :)

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 31, 2010, 07:02:57 AM
^^^ No pics?

I just finished a new 'modder's delight' layout which includes cathode resistors and bypass caps as well as grid stoppers. Anyone interested?

Any news on this one? I finished first MO and its great, I still have some tubes left, and want to try another one with fancy enclosure and everything :)



The layout and accompanying schematic are done, I just need to breadboard it again in order to make some build notes. Within a week.  ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: dimi3 on May 31, 2010, 01:18:55 PM
wow, thats great, I will wait for it, when desinging PCB for it, any chance to do a little wider PCB traces?
thanks for sharing.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 31, 2010, 01:55:47 PM
....when desinging PCB for it, any chance to do a little wider PCB traces?

Way ahead of you!  ;)
Title: All New "Murder One" redesign and layout!! Modder's Delight!
Post by: frequencycentral on June 12, 2010, 12:34:18 PM
The original Murder One was 'baby's first amp'. I've learned a lot since then and the design has gradually changed over time. This one is a major upgrade, and now it's looking much more like a serious amp. What's changed:



The result of these additions is that the anodes are running at much higher voltage, the clean sound is much better than it was - very usable now, and the cranked sound is fatter and has more body.

As this is the Modder's Delight version, any tweaks to suggested values should be considered in conjuction with this article: http://www.diystompboxes.com/pedals/tubedummy.html

I have verified the new layout onto perf, it works really well. If anyone feels like etching me a board or two I'd be proud to accept them!

(http://i210.photobucket.com/albums/bb292/frequencycentral/MurderOneV6.jpg)

(http://i210.photobucket.com/albums/bb292/frequencycentral/ModdersDelightPCB.gif)

(http://i210.photobucket.com/albums/bb292/frequencycentral/ModdersDelightPnP.gif)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kurtlives on June 12, 2010, 03:20:23 PM
Cool, you shouldn't need C17 though. All DC voltage is being blocked by C14.

Maybe you have it there for the bias voltage you are generating with the MAX thing.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: elshiftos on June 13, 2010, 08:23:30 AM
A couple of questions if I may....
What is the HT voltage, and is the OP transformer the same as the fender reverb type?

Thanks  :)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: panterafanatic on June 13, 2010, 08:47:06 AM
The HT voltage is about 80 or 90 volts if I remember correctly, the max voltage on the pentode is 100v, so you could get away with anything from 110 or lower pretty safely, possibly higher. That is with 12 volts input, with 9, you'll have lower results I believe. For this you may want a separate 12v 500mA DC power supply.

And yes, it is the same transformer. Though any 22k:8 to 25k:8 should work well.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: max30 on June 13, 2010, 01:10:27 PM
Great update, thank you, 2 questions regaring the latest version, can MAX 1044 can be used still? or new IC is preffered? Could you post the dimensions in mm for new PCB?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: panterafanatic on June 13, 2010, 01:15:14 PM
I dunno about the dimensions, but you can easily scale the board by printing out a scrap sheet, then scaling accordingly to IC spacing, .1" dunno what it is in mm, for some reason I'm blanking on the ratio atm.

The MAX1044 is preferred imo, unlike a 555 timer charge pump, you can make the frequency far above audio, whereas the 555 takes a little more care to make completely stable for audio use, although it can still be done.

edit: one inch is 24mm come to think of it. so 2.4mm is IC spacing.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on June 13, 2010, 01:30:17 PM
I recently asked John Lyons about scaling from DIYLC gifs, he said:

Quote from: John Lyons
I scale it to a .1 inch grid in photoshop. An ICs pin spacing will match the grid when correctly sized.

The ICL7660S has an identical frequency boost feature to the MAX1044, with the advantage that it's maximum rated input voltage is higher, and it's cheaper. Murder One will still work with a MAX1044, but 12 volts slightly exceeds the MAX's maximum rated input voltage. If you use ICL7660S, be sure to use the 'S' suffix chip, as the standard version lacks the frequency boost feature.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: max30 on June 14, 2010, 01:56:52 AM
in DIY layout creator SW the scaling is 0,1" per row so number of rows and columns shoud give you the exact dimension of PCB.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Davidgwells on July 07, 2010, 10:26:28 PM
Just finished building my murder one, thanks Rick!  It sounded great for a little while and now the power supply is dead.  Any ideas why this happened or where to start looking?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 08, 2010, 02:21:51 PM
I've built quite a number of these. The only issue I've come across is human errors using an AC power supply or reverse polarity DC power supply. Have you measured your DC input voltage? It's probable the charge pump has failed, maybe you have a short somewhere in the diode/cap ladder, or an incorrect wiring? It's worth noting that the caps in the voltage multiplier will hold a charge for many hours unless drained down, any shorts created while tinkering could easily blow the charge pump. I use a ICL7660S nowadays as it's voltage rating is higher than a MAX1044.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Davidgwells on July 08, 2010, 11:04:08 PM
Thanks Rick.  I guess I should clarify that it was the wall wart that got fried.  Previous to that, the amp only worked with certain cabinets some of the time and one specific cab all of the time.  At the time it quit the murder one was plugged into a 16ohm cab but powered down.  Moments before that it was working with the cab just fine.  Clearly I have a short somewhere but damned if I can track it down!  I opened up the wall wart and several components are burnt.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Davidgwells on July 16, 2010, 02:46:40 PM
What, am I a thread killer??   So I just got a new wall wart, triple checked for polarity, installed a new tc1044 chip an turned it on.  There was a high end whine coming from the speakers but other than that it sounded pretty good until the volume started to fade.  Once again, the wall wart is dead.  I'm certain that polarity is correct and I've traced the signal path countless times and can't find a short.  I'm ready to tear it all down and start over!  Any suggestions anyone?  Why am I blowing wall warts with this but only after a few minutes?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 16, 2010, 03:07:40 PM
Weird. What is the spec of the power supplies you've burned out? How many milliamps? I recommend 500ma.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Davidgwells on July 16, 2010, 03:10:58 PM
The first was 12vdc 500ma, the second was 12vdc 600ma. 
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: igerup on August 06, 2010, 04:03:32 PM
An interesting thread, this one. I noticed that in the early stages of circuit developments (and your first build of this most interesting little amp) you connected the 0 ohm (ground wire) of the output transformer to ground. But you did not use an insulated output jack.  I know the B+ is lower than 100 volts and the amp most likely doesn't send 2.5 A to the speaker (like the averag 100 watter does). But output current will still be way higher than in the preamp, you don't want that in the preamp so use insulated output jacks. . The OT ground wire should only be connected to ground at the same place as the first filter cap.

For more info check http://www.aikenamps.com/ (http://www.aikenamps.com/) in the tech info section. There's some very good info on ground wireing there which also applies to submini tubes.

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: criszou on October 06, 2010, 09:14:23 PM
Hi, Rick
I'm sure you had record Murder One on computer soundcard. In this case, do you mic it, or use DI box, or direct to your soundcard?
What is Muder One's impedance for the load box?
I have collect  the kits one by one ^^. Do I have to concern about 110V or 220V? In here use 220v.

Thank's
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Cliff Schecht on October 07, 2010, 02:05:56 AM
An interesting thread, this one. I noticed that in the early stages of circuit developments (and your first build of this most interesting little amp) you connected the 0 ohm (ground wire) of the output transformer to ground. But you did not use an insulated output jack.  I know the B+ is lower than 100 volts and the amp most likely doesn't send 2.5 A to the speaker (like the averag 100 watter does). But output current will still be way higher than in the preamp, you don't want that in the preamp so use insulated output jacks. . The OT ground wire should only be connected to ground at the same place as the first filter cap.

For more info check http://www.aikenamps.com/ (http://www.aikenamps.com/) in the tech info section. There's some very good info on ground wireing there which also applies to submini tubes.



I prefer to use the chassis as the ground for the speaker jacks, the speakers don't care and the chassis makes a great conductor for all of that return current. I keep this current out of the input sections by isolating the input stage (and usually subsequent stages) ground and only having this ground meet the others at the "-" side of the decoupling capacitor. This is physically the best place to run every ground to, but usually not the most convenient.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: merlinb on October 07, 2010, 06:07:20 AM
I prefer to use the chassis as the ground for the speaker jacks, the speakers don't care and the chassis makes a great conductor for all of that return current.
Yikes! What awful advice. The chassis is not just one 'big fat wire'! You can get away with it, but don't make a habit of it...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Cliff Schecht on October 07, 2010, 01:21:13 PM
You think so? I don't rely on the chassis ground for everything mind you, actually I prefer to not use the chassis at all as a ground. The only place that I let the chassis ground touch the signal ground is where the speaker jack meets the chassis, but even this gets a direct connection to the B+ decoupling cap "-" terminal. Essentially the only place that chassis and signal ground touch is at the speaker jack. Keeps the noise WAY down in amps, at least the 60/120 Hz variety. Unless I'm doing something vintage inspiried, I typically decouple my amps like you show on your grounding page.

I guess the big point to make here is to know and control where your large return currents flow so you can keep them out of the input. The easiest way to do this is an isolated input jack, the output jack isn't anywhere near as picky because the SNR at that point is stupid large.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: merlinb on October 07, 2010, 04:31:39 PM
The only place that I let the chassis ground touch the signal ground is where the speaker jack meets the chassis, but even this gets a direct connection to the B+ decoupling cap "-" terminal.
OK, at first it sounded to me like you were using the chassis to actually carry speaker current.

Incidentally, for lowest noise you want you only circuit-chassis connection at the input jack. (As you pointed out, the speaker is insensitive to noise, so you don't want to waste your connection there).
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Cliff Schecht on October 07, 2010, 04:38:58 PM
The only place that I let the chassis ground touch the signal ground is where the speaker jack meets the chassis, but even this gets a direct connection to the B+ decoupling cap "-" terminal.
OK, at first it sounded to me like you were using the chassis to actually carry speaker current.

Incidentally, for lowest noise you want you only circuit-chassis connection at the input jack. (As you pointed out, the speaker is insensitive to noise, so you don't want to waste your connection there).

This is what Trainwreck's and some other amps do and it does work, but there are better methods out there. It's not as bad of ju-ju on an aluminum chassis but you're asking for trouble with steel because of the slightly higher resistivity and the fact that steel can couple EMI from transformers and such while aluminum doesn't.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Davidgwells on October 17, 2010, 07:23:19 PM
Anyone want to fact check my wall wart pick?  I have let my murder one sit, non working, for a few months and i'm ready to dive back in.  The link is for one I found on mouser, does this look like the right choice?

http://www.mouser.com/ProductDetail/Xicon/412-112054/?qs=sGAEpiMZZMtpkqKkT5w3ugVzZMH3McLBpaXAxv7xPGM%3d
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: zambo on October 18, 2010, 02:01:23 AM
It looks as if it is the right kind. I havent built a murder one though.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: max30 on November 06, 2010, 06:28:05 AM
Hi,

I build the last PCB version of this amp, but I have a problem with it, it looks that output tube is not working, I'm getting the sound from the amp, but the power tube doesent seem to be glowing or get hot. I changed the tube but the same result.

what could be the problem? between pin 3 and 5 on the output tube I have only 1.5V i think this is too low for HT voltage? On the first tube I have a little over 6V between pin 3 and 6, also the first tube lights up.

Am I getting the sound only from preamp tube?

Thanks for the help I hope to get it working.

Here are some pics, not the best guality:

http://www.shrani.si/f/2u/xD/dCqFkEf/img00015-20101106-1104.jpg
http://www.shrani.si/f/34/Rq/vdm8GUe/1/img00020-20101106-1129.jpg
http://www.shrani.si/f/n/Jk/22ypE7E0/1/img00021-20101106-1130.jpg
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on November 06, 2010, 07:03:37 AM
The 5672 will not glow or get hot, that's normal. As pin 3 gets ~1.25v and pin 5 is grounded, the voltages you have between pins 3 and 5 are normal. Pins 3 and 5 are the heater connections, this tube has a very low heater voltage and current. You should find more serious voltages at pin 1 and 2.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: max30 on November 06, 2010, 07:37:05 AM
Hi frequency,

I soo stupid  :D, I didnt work with 5672 tube before and didnt know that they dont glow. Anyway, I havea very good sound out of this amp, but only volume is not as expected, the amp is as loud in 2x12 speaker cabines as let say TV on normal home music listening. Should I expect more?

On the 5672 i have the following voltages:

between pin 1&2 between 5 and 6V its changing constantly :) if bias switch in first position and 3,2 if in second, when in position when voltage is drifting I get some motroboating sound also.

between pin 1 and 3 i have 65V
between 1 and 4 i have 75V
between 1 and 5 67V
between pin 2 and 3 I have 69V
between 2 and 4 i have 75V
and between 2 and 5 i have 70V

Is this ok?

Thank you for the help.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: alanwf on November 26, 2010, 03:47:35 AM
Hi Rick,

I'm filling out my Mouser order now! Thanks for this great project. My first charge pump usage. Looking at the data sheet for the 1044, there is a suggestion to parallel them (or even more than two) to lower power supply output resistance and up current—both seem advantageous for only an extra chip and pin 2 to 4 cap. Have you tried this? Or are the current demands so low as to make this overkill?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: patrickbrose on December 05, 2010, 05:12:23 PM
Has anyone tried a switching power supply yet?
Has the issue of isolating the output jack been (yes or no) been answered?
I found a TC7660S. Is this the same as the ICL7660S, just a different manufacture?
-P
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on December 05, 2010, 06:03:22 PM
Looking at the data sheet for the 1044, there is a suggestion to parallel them (or even more than two) to lower power supply output resistance and up current—both seem advantageous for only an extra chip and pin 2 to 4 cap. Have you tried this? Or are the current demands so low as to make this overkill?

No need, there's enough current anyway.

Has the issue of isolating the output jack been (yes or no) been answered?
I found a TC7660S. Is this the same as the ICL7660S, just a different manufacture?
-P

I never found an issue with the output socket being grounded, and I've built dozens of these.

According to the data sheet, the TC7660S will be fine.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: patrickbrose on December 05, 2010, 08:05:43 PM
Thanks Rick,
Does anyone have a suggestion for a power supply for this thing? I need US specs. All I can find is a switching power supply which according to Rick is no good. So what say you? 12VDC, 500ma regulated
-P
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: MetalUpYerEye on January 30, 2011, 07:44:18 PM
How loud is this amp? Could it be compared to a 386 based amp (like the Ruby) volume-wise?

I've been wanting to try a tube amp build but don't want to drop $300 for all the necessary parts for a 5 watt. This seems right up my alley since its all-tube and would cost me less than $100 to build... I don't etch so... Where could I get my hands on a PCB for this bad boy?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: MetalUpYerEye on January 31, 2011, 07:04:20 PM
No replies to this topic?

Is this a dead project or what?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Taylor on January 31, 2011, 07:13:24 PM
Rick has not been posting as much lately.

I do think this would be comparable to a 386 amp in terms of volume. It's a cool unit, though I haven't built one as I play bass. But if you're looking for something more than 1/5 of a watt, the Firefly is around 5 watts I think, and could probably be built for around $100.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: therecordingart on January 31, 2011, 07:20:30 PM
Rick has not been posting as much lately.

I do think this would be comparable to a 386 amp in terms of volume. It's a cool unit, though I haven't built one as I play bass. But if you're looking for something more than 1/5 of a watt, the Firefly is around 5 watts I think, and could probably be built for around $100.

The Firefly is about 1.5 watts and was about $200 to build (built one last year).
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Scruffie on January 31, 2011, 07:23:12 PM
You could do what i'm doing and build the Super Fly (Another of Ricks Amps... but also the Firefly so not) but use normal 12AX7 & AU7.

Be Quietish and Cheapish.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Taylor on January 31, 2011, 08:09:20 PM
The Firefly is about 1.5 watts and was about $200 to build (built one last year).

Hmm... 0 for 2 on my part. Sorry!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: MetalUpYerEye on February 01, 2011, 11:00:16 PM
I'm looking for something like the Ruby. I have a friend who currently has my Ruby and is deeply in love with it. I figured i'd build one for him but I was already going to build the "Murder One" for myself, figured I might as well double my fun and make 2 murders and really blow my friends pants off... In a totally asexual way.

Any word on PCB's for this? Or should I resort to desperate times: perfboard?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: zambo on February 02, 2011, 01:26:33 AM
if you make on of these with a 12au7 selp split power tube and a 12ax or au7 preamp tube you can pretty much wire the whole thing on the tube sockets themselves. It works quite well. I also use the lt1054 ( i think ) from small bear for these supplies. They are cheap and available. If you run the power supply up at around 100 volts they are fairley loud. louder than a 386 amp i think. If you use a switching supply you can run them around 200 volts or so and they are actualy kinda loud. i like to use the firefly schematic and just run different voltages. i also leave off the cascode boost tube stage so i only need two tubes. hardware store aluminum makes a decent chassis that is pretty easy to bend. Good luck, Greg
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: phector2004 on April 18, 2011, 06:36:02 PM
Hey Rick,

Would it be a bad idea to use the 16V 4A adapter I bought for Taylor's Tiny Giant amp to power this thing up?

I'm thinking of using two regulators to get 6V and 12V for filament and circuit use.

Thanks
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Haynesarama on July 23, 2011, 07:36:27 PM
Hi There Rick.

Very nice looking amp design  ;D
Hats off to you!! I'm wanting to build one to use for practicing at lower volumes at home and for recording with cubase.
I have a couple of questions to ask first if I may  :D
If I wanted to hook this up directly to my computer will I need to make some kind of DI out for this?
I've noticed in one of the threads for the Murder one amp that you built one for a customer who wanted the ability to use his Murder one as a preamp also.
Would it be something like this I would need to do to hook it up to my computer or something different?
Do you have any advice on how to go about implementing this? It'd be greatly appreciated.

Also Is there a standard size tube that I could substitute easily for the 6111 and 5672 Or is that a silly question?

And finally where do you purchase the covers I've seen In the build pictures for the output transformer?
I've looked all over for some but can't find any......It'd probably help if i knew what they are called though!! Lol  ;D

Cheers
Michael  :icon_wink:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 24, 2011, 06:19:34 PM
If I wanted to hook this up directly to my computer will I need to make some kind of DI out for this?
I've noticed in one of the threads for the Murder one amp that you built one for a customer who wanted the ability to use his Murder one as a preamp also.
Would it be something like this I would need to do to hook it up to my computer or something different?
Do you have any advice on how to go about implementing this? It'd be greatly appreciated.

You can take a pre out from lug 2 of the volume pot, like I did here: http://www.diystompboxes.com/smfforum/index.php?topic=83831.0  The output will be pretty hot though. I've built a few Murder One with a DPDT which switches the output socket from speaker to preamp, as well as cutting power to the pentode.

Also Is there a standard size tube that I could substitute easily for the 6111 and 5672 Or is that a silly question?

That would be a different amp altogether.

And finally where do you purchase the covers I've seen In the build pictures for the output transformer?
I've looked all over for some but can't find any......It'd probably help if i knew what they are called though!! Lol  ;D

The transformers I use are Hammond 1750A, and come like that as stock.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on July 27, 2011, 02:01:49 PM
My tame shred master Rich Russell did me some soundclips: http://dl.dropbox.com/u/967492/Murder%20One%20Montage.mp3

(http://dl.dropbox.com/u/967492/MOMC/MC3.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Haynesarama on August 07, 2011, 07:54:50 PM
Hi Rick.

Right then. I've got most of the Parts in stock to build the modders delight version.
I'm just struggling to get the 2 watt 18r resistors. I can find 3 watt 18r resistors, can I use these?
I can also get 1.6 watt 18r resistors if that's any better?

Also what values should I be experimenting with r13a?
And finally where in the UK (Lincolnshire) are you getting the d bar handles to protect the tubes?
I can't find any anywhere near small enough.

Thanks in advance
Michael :)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on August 08, 2011, 03:22:44 AM
Hi Rick.

Right then. I've got most of the Parts in stock to build the modders delight version.
I'm just struggling to get the 2 watt 18r resistors. I can find 3 watt 18r resistors, can I use these?
I can also get 1.6 watt 18r resistors if that's any better?

Also what values should I be experimenting with r13a?
And finally where in the UK (Lincolnshire) are you getting the d bar handles to protect the tubes?
I can't find any anywhere near small enough.

Thanks in advance
Michael :)


3 watt is just fine (better even if it fits your case) , 1.6 watt may work but you need to do the math, rick is dropping about 5.7 (12 - 5.7 = 6.3 volts, what the these tubes like on their heaters) volts so ohms law says V = I *R or V/I = R in this case, according to the datasheet the heater will pull .3 amps
 
Rick got 18 ohms I assume from doing the math of dropping 5.7 volts  =  5.7/.3 = 19 ohm (18 is close enough and probably the closest standard value)
using what we have v = I * R or V = .3 * 18 = 5.4 volts
to find wattage ,there are a few formulas but this works
Watts Law   Power = Voltage * Current
5.4*.3 = 1.62 watts
The other way is P = I^2 * R
.3^2 * 18 = 1.62 watts 

so all of that to say 1.6 would work, but you would be at the limit of that resistor and could have issues, It a rule of thumb to go x2 as big, Rick decided that 2watts was enough and it works for him every time as far as I know.


hope that helps :)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 08, 2011, 03:27:48 AM
^^^

Yup, I concur.

The roll bars sre from B&Q.  ;)

I'm using a newer layout these days, without the stuff for the bias switch, which was a hangover from earlier versions. I'll post it up later.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Haynesarama on August 08, 2011, 07:37:11 AM
Hi Steve and Rick.

Thanks for your speedy responses :)

Steve cheers for putting your time in to do the math,
That's it then 18r 3watt resistors ordered, I'm good to go once
Everything arrives :)

Rick I'll look forward to seeing your updated files,
I should learn to be more patient, I've just etched myself
Your modders delight board from page 14! Lol :)

Now to grab some of those pesky roll bars!
I'll keep you all posted.

Cheers
Michael
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 08, 2011, 07:48:37 AM
This is the layout I've been using for a while, verified. Version 7 - I'm such a tweaker. It dispenses with the bias switch and associated circuitry. It also includes (orange) pads and swiching diagram for adding a pre-out using the existing speaker out socket - it basically takes a tap from the preamp stage and also cuts power to the pentode when switche to pre-out mode. If you dont want the pre-out switch you'll need to jumper the orange pads together.

BTW, it's easy to build teh Modder's Delight without the bias switch, just a matter of not using a few components and wiring it slightly differently.

(http://dl.dropbox.com/u/967492/V7%20MD%20%2B%20pre%20out%20PCB.gif)
(http://dl.dropbox.com/u/967492/V7%20MD%20%2B%20pre%20out%20PnP.gif)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: askwho69 on August 10, 2011, 11:39:15 AM
where can i order 6111, 5672 and the 1750a transformer same site? anyone? if i order piece by piece it will cost me shipping :( please anyone?

A2

Thank you so much God for bringing Rick Holt in this forum :D

God Bless
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 10, 2011, 12:29:59 PM
Small Bear sell 6111 and 5672.

Thank you so much God for bringing Rick Holt in this forum :D

 :icon_redface:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Govmnt_Lacky on August 10, 2011, 12:42:36 PM
I might be a bit dense Rick but.... where is the circuit Output  ???

I see the input, I see power and ground, I see your switching diagram but, I am still missing where the signal is coming from to go to the Output jack.

When the switch is one way, the signal is coming from the Transformer (red wire) and when it is the other wsay, it is coming from the Volume pot (green line)

Do these wires get removed from the board and soldered to the switch? Do those holes then get left open?

Sorry if I am a little dumb!! Working long hours this week  :icon_eek:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on August 10, 2011, 06:28:01 PM
the two transformer outputs. :)

I do not see the loading for the transformer, but that may be a single load transformer I have not looked it up
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Blackface007 on January 16, 2012, 01:17:35 PM
This is the layout I've been using for a while, verified. Version 7 - I'm such a tweaker. It dispenses with the bias switch and associated circuitry. It also includes (orange) pads and swiching diagram for adding a pre-out using the existing speaker out socket - it basically takes a tap from the preamp stage and also cuts power to the pentode when switche to pre-out mode. If you dont want the pre-out switch you'll need to jumper the orange pads together.

BTW, it's easy to build teh Modder's Delight without the bias switch, just a matter of not using a few components and wiring it slightly differently.

(http://dl.dropbox.com/u/967492/V7%20MD%20%2B%20pre%20out%20PCB.gif)
(http://dl.dropbox.com/u/967492/V7%20MD%20%2B%20pre%20out%20PnP.gif)

Hi Rick,
I built "Murder One V7" using 6112 as preamp. It sound pretty cool, especially if I crank it. But up to 50% Gain it start to "motor booting" or almost "vibrato" altough I do not use LFO like your "Vibracaster". Any advise to eliminate the "motor booting"? Should I icrease the C15 (10µf) or R10 (1.8 K)? Or is it enough to change the tube preamp to 6111? I'm still waiting of my 6111.
Thanks
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 16, 2012, 01:47:02 PM
Nice. 6112 is like twice the gain of 6111. It will require higher anode resistors ( R1, R2 - try 100k) and probably a higher value grid stopper ( R12 - try 470k).

If it still motorboats after changing those value, try cutting the HV trace between C12 and R1/R2 and bridging the cut trace with a 22k resistor. For completeness, also consider adding another 10uF 100v cap between R1/R2 and ground. Basically, cutting the trace, bridging it with the resistor and adding the extra cap is creating a B1 (to the 5672's B+), really you're converting the preamp section to a Superfly preamp.

BTW, I've got a few spare etched PCBs and tube sets if anyone wants one.

(http://dl.dropbox.com/u/967492/PCB%20Sales/MO%20x%204.jpg)

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Blackface007 on January 19, 2012, 01:59:40 PM
Nice. 6112 is like twice the gain of 6111. It will require higher anode resistors ( R1, R2 - try 100k) and probably a higher value grid stopper ( R12 - try 470k).

If it still motorboats after changing those value, try cutting the HV trace between C12 and R1/R2 and bridging the cut trace with a 22k resistor. For completeness, also consider adding another 10uF 100v cap between R1/R2 and ground. Basically, cutting the trace, bridging it with the resistor and adding the extra cap is creating a B1 (to the 5672's B+), really you're converting the preamp section to a Superfly preamp.

BTW, I've got a few spare etched PCBs and tube sets if anyone wants one.

(http://dl.dropbox.com/u/967492/PCB%20Sales/MO%20x%204.jpg)

Thanks a lot Rick for your answer.

how to have the pcb Rick?

Regards



Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Blackface007 on January 19, 2012, 02:11:25 PM

If it still motorboats after changing those value, try cutting the HV trace between C12 and R1/R2 and bridging the cut trace with a 22k resistor. For completeness, also consider adding another 10uF 100v cap between R1/R2 and ground. Basically, cutting the trace, bridging it with the resistor and adding the extra cap is creating a B1 (to the 5672's B+), really you're converting the preamp section to a Superfly preamp.



should I put 22K (cutting HV trace) before connection to transformator or after?

Thanks again Rick
Regards
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 19, 2012, 02:16:54 PM
I'd put it immediately before R1/R2. Say roughly parallel with the 6112.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Blackface007 on January 19, 2012, 02:26:11 PM
I'd put it immediately before R1/R2. Say roughly parallel with the 6112.

Thanks a lot Rick. I have to do it tommorow night, because I don't have the right value for R1/R2 and R12. I let you know the result.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Blackface007 on January 22, 2012, 07:14:22 AM
Nice. 6112 is like twice the gain of 6111. It will require higher anode resistors ( R1, R2 - try 100k) and probably a higher value grid stopper ( R12 - try 470k).

If it still motorboats after changing those value, try cutting the HV trace between C12 and R1/R2 and bridging the cut trace with a 22k resistor. For completeness, also consider adding another 10uF 100v cap between R1/R2 and ground. Basically, cutting the trace, bridging it with the resistor and adding the extra cap is creating a B1 (to the 5672's B+), really you're converting the preamp section to a Superfly preamp.

BTW, I've got a few spare etched PCBs and tube sets if anyone wants one.


Hi Rick,
I use 120 K Ohm for R1/R2 and 510K for R12, also applied C12 and 10 µF. The sound is much better, "motor boating" can be eliminated, if I crank it can be very cool. Now I come to the next problem, the sound is cutted earlier as I expect, i.e. if I pick string E Low, the "sustain" is stopped much earlier (even earlier than a Django style guitar). After picking a string the sustain makes hingher volume and suddenly (millisecond) niose and than stop. Any suggestion? Bad tube maybe ?
Regards
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: zambo on January 22, 2012, 04:58:14 PM
Im not Rick, but it sounds like it could be a cold solder joint.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Blackface007 on January 23, 2012, 01:05:29 PM
Im not Rick, but it sounds like it could be a cold solder joint.

Hi Greg,
thanks a lot for the suggestion. I'll check (resorder) it.
Regards
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Blackface007 on January 28, 2012, 02:48:41 AM
Im not Rick, but it sounds like it could be a cold solder joint.

Hi Greg,
thanks a lot for the suggestion. I'll check (resorder) it.
Regards

Thanks a lot Greg and Rick. I have soldered the 6112 and 5672 directly into the board without IC socket. Now, it sounds really great for me. I love it; cranked sound. I need to learn more the theory tube before I go to the next..... project.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: zambo on January 28, 2012, 04:52:05 PM
Awesome!   :) gonna post a clip?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on January 29, 2012, 05:07:24 PM
Put this together today (thanks for the board, Rick) and was just trying it out.  Not boxed or anything just yet, but jury-rigged on my desk to a spare (4R) speaker.

Gets nice and warm and the 6111 glows reassuringly.  But I notice I get an unexpected tremolo when the gain is past 8 or 9 and as the signal fades out (i.e. not noticeable when played continuously hard, only when the signal fades).  Any ideas?

My PSU is giving 11.7V (IC1 pins 1 & 8).  I notice the B+ is oscillating gently between about 61V and 62V (somewhere between 1 and 2 Hz?).  Does any of this sound right?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 29, 2012, 07:19:18 PM
Sounds a little off. Something's wrong there.....cold joint again? Also check for shorts in the multiplier - it should be putting out a few more volts than that.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on January 30, 2012, 07:58:05 AM
Thanks Rick, I shall take an even-closer look at my handiwork.  I was post-gig tired yesterday, so anything could have happened...   :icon_wink:  BTW, how many "few more volts" should I be expecting?  I'm assuming after each diode I should see another 12V (11.7V!) less a diode drop?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on January 30, 2012, 02:48:53 PM
DMM has done its bit.  Here's how the charge pump is looking:

After D15, 15.7V.
D2 = 20.0V
D4 = 20.2V !
D6 = 36.4V
. . .

OK, even I can see a break in the pattern here!  :)  Looks like something went awry around D3/D4 in the chain?  I'm assuming that since B+ is not zero, this is more likely to be short- than open-circuit?  I've been staring at this area through a magnifying glass for many, many minutes and can't see anything obviously wrong.  Does a fried 1N4148 go short-circuit?  And I thought I'd been deadly efficient with my soldering.  Perhaps just deadly...  :icon_neutral:  Actually, the diode/continuity test seems to show all the diodes with a small forward resistance and open backwards, so perhaps they're all fine and dandy.

Am I getting warm, or is that just the 6111?  Will continue to peer and probe in the meantime...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on January 30, 2012, 04:03:09 PM
Ooh, my bad!  DMM was having a little brain-fart of its own.  (I know how it feels.)  The middle segment of digit two was out to lunch.  So 20.2V was actually 28.2V!

Anyways, that means the voltage is climbing the ladder alternately ~4.4V and ~3.8V per rung.  And I'm none the wiser...   ???

EDIT: btw, is the 7660 supposed to be getting rather warm?  After the 6111, it's the warmest thing on the board.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on January 30, 2012, 04:09:30 PM
A warm 7660 is indicative of an error somewhere. Really double check there is no hairline shorts in the multiplier, particularly around the 7660 pins 2 and 3. You may not even see it, it'll be that fine. If ever I'm in doubt I gouge away with the thin edge of tweezers until I'm 100%.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sadcakes on January 30, 2012, 04:20:20 PM
Hi,
I can't offer any help, but I have also just finished my build using the V7 PCB and I am experiencing the exact issue that Bluebunny is.
With both gain and Volume up full there is a tremolo style oscillation.
Reducing either control to about 8 removes this.
I also am getting 11.68v across pins 1 and 8 of the 7660S.
Very interested to hear if you find the source of your issue.   :)
Sean
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sadcakes on January 30, 2012, 04:36:55 PM
Hi Rick, I've removed the (hot) 7660 and checked for shorts. I am getting a reading between pins 2 and 3, when all the others are open.
Is this an indication of a faulty IC?
Thanks
Sean
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on January 30, 2012, 05:31:34 PM
Thanks for the advice again Rick.  I don't think there's a short between 2 and 3 'cause they show different signals on my little oscilloscope.  But I shall have a good gouge anywhere there are close tracks.  But will have to wait until tomorrow - will let you know how it pans out, Sean.  I'm past tired and being awake is probably a good idea for continuing with this one!  Up early tomorrow morning (like always) so kip is sadly #1 priority right now.  Even my daughter has just come in and said "aren't you supposed to be in bed?".  Bloody cheek...  ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Blackface007 on January 31, 2012, 02:33:29 PM
Sorry, I have deleted my posting, to avoid any confusion.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 02, 2012, 08:31:11 AM
OK, been over it with a fine-tooth magnifying glass and gouge!  No unexpected shorts.  7660 still getting warm.  One thing I did notice: the "tremolo" effect at high gain seems to be a sub-sonic pulsing.  Having the benefit of daylight (working at home today), I can see the speaker is bobbing up and down gently but inaudibly.

Anyway, I was wondering about duff or rogue parts - particularly since you indicated warm 7660s aren't a good sign.  I'll try swapping it out and see what happens.

I'm determined to sort this out.  It's a great design and I have an amusing "re-purposed" enclosure sitting waiting for it...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 02, 2012, 09:53:35 AM
New 7660 made no difference.  This one from HK, the first was from Rapid.  Speculated offline with sadcakes that the 7660 might be hot because of its proximity to that 18R voltage-drop resistor?  Contrary to what I said earlier, this is the hottest point on the board - close to boiling!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sadcakes on February 03, 2012, 03:17:50 PM
Ok, I definitely need some help now!
I've just completed build version 2 using the second of Rick's v7 boards that I ordered and some new components.
I have checked the build as thoroughly as I did the first at every point along the assembly.
Despite this, this version is experiencing the exact same effects as my first build. With both Gain and Volume on full there is a tremolo like oscillation.
Can anybody who has successfully built  the V7 using the PCBs perhaps assist?
Could it be my off board wiring?? ???
thanks a lot
Sean
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sadcakes on February 05, 2012, 11:41:35 AM
So I managed to fix this myself..

Using Rick's advice to Blackface007 I swapped out R1 and R2 for 100k values and also replaced R12 with a 470k.

This has removed the 'motor-boating' oscillation I was experiencing at full volume even though I am using a 6111 tube as per the schematic.

Bluebunny - you may want to give this a try!

The only issue I have now is excessive background noise/hiss at full volume but I'm hoping this will be reduced once I have it in an enclosure...

Oh and if anybody can offer an idiots guide how to wire up the Pre-out switch (currently I have the orange pads jumpered) that would be much appreciated! For some reason the illustrated pic makes no sense to me!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 05, 2012, 12:58:16 PM
Here ya go!

_______________________________________________________________________________________________________________

Basic build:

(http://dl.dropbox.com/u/967492/Version%207/M1V7%20Stock.gif)

________________________________________________________________________________________________________________

Added switch to select preamp or power amp at output socket:

(http://dl.dropbox.com/u/967492/Version%207/M1V7%20Switched%20Pre.gif)

What's happening in the above layout is that the preamp out is taken from lug 2 of the volume control. One half of the DPDT selects either the preamp or the power amp to the output socket. The other half of the DPDT cuts HV to the pentode and the output transformer when the DPDT is in preamp mode - as it's bad for the pentode and transformer to see high voltage without a speaker attached. I'd really stress that caution needs to be taken with this switch, as you don't want to send the power amp output into anything other than a speaker. It's a cool mod though - in preamp mode you've got a massive warm tube overdrive 'pedal' type effect.

_______________________________________________________________________________________________________________

So....there is a third way to wire up the Murder One, which is to include separate sockets for preamp out and speaker out. If you do this you'd want to use a switched socket for the speaker out and include a dummy load across it, so that the power amp and transformer are seeing a load even when there is no speaker plugged in. If anyone wants to build it this way I'll work up a wiring diagram.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: sadcakes on February 05, 2012, 01:14:57 PM
Rick, you are a star!
That's perfect, thank you.
Sean
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 06, 2012, 06:14:41 AM
Thanks Sean, I'll give those resistor mods a try.  I'm WFH today - snowed in (that's what I told the office!) - so I may have a go during my "lunch break".  ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 06, 2012, 01:49:36 PM
Wey hey!  No more tremolo!  Thanks for the heads up, Sean (and Rick's advice to blackface007, which I'd clearly missed...).  Now I just need to get to the bottom of the measly ~62V at the end of the charge pump, cos, how can I put this? - it's a bit quiet!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on February 07, 2012, 12:13:20 AM
Wey hey!  No more tremolo!  Thanks for the heads up, Sean (and Rick's advice to blackface007, which I'd clearly missed...).  Now I just need to get to the bottom of the measly ~62V at the end of the charge pump, cos, how can I put this? - it's a bit quiet!

which diodes are your using? some drop more than others, can you post your voltages for each drop measured off C2, C4, C6 ect...

charge pumps work by packing electrons in to the capacitors, by oscillating, the capacitor dumps across the diode, when packing more electrons across the diodes you get more voltage. With this design its a latter where you get a voltage with no load, once there is a load there are not enough electrons left to = said voltage and you see the voltage drop.
you could have a power supply that is not supplying enough current causing this supply to SAG.
Also this tube puts out 65mw. I have built amps using 12k5 which have the same power output and they are quite, this is not a jam with the band amp, but a tone amp. add an inefficient speaker and its worse.  I use a Red Coat Wizard which is a 103db @ 1watt. In a similar amp I get 70db at one foot, according to my meter. 70db is quite, but loud enough to record or mic.

if you built off the board design, you could try some things, different wall wart, or use 13v supply. this is over the chip rating, and with Rick's voltage drop raises the heater voltage on the power tube. So is not a great option .

Schottky diodes will drop less voltage, giving you a slightly higher voltage at the end. A BAT41 is rated at 100 peek inverse voltage and 100ma. so it should work with no issues. the 1N5711 can be used also up to that last two diodes in the chain. Then your getting to close to its 70v max inverse voltage. 


Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 07, 2012, 08:11:37 AM
Thanks for the additional comments, iccaros.  I've got a string of 1N4148s, as per Rick's design.  I'll power up again this evening when I'm home and check the voltage at each step.  The PSU should be fine: it's a 1A 7812-based job - hopefully plenty for this and one or two more of Rick's tube pedals...   :icon_biggrin:  The speaker is culled from a TC-Helicon VSM300XT, so I'm hoping it's not too inefficient (though I readily admit something more "guitar" might be more appropriate).  Will keep in mind the diode sub suggestion, though I do *hate* de-/re-soldering!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 07, 2012, 02:15:00 PM
OK, here's the story down that charge pump:

C2 = 20.3V
C4 = 28.8V
C6 = 37.3V
C8 = 45.8V
C10 = 54.3V
C12 = 62.8V

By my calculations, and according to the 7660S datasheet, it should increase by my starting 12V less two 1N4148 drops each step?  Assuming 1V VF per diode (again according to the datasheet) I should get 72V at the end?  Where'd my other 9.2V go?   ???
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on February 09, 2012, 03:09:19 AM
@BlueBunny
This voltage multiplier doubles voltage Charging the first capacitor and at another point causing it to discharge, charging the next capacitor.  This is added in stages so that the starting voltage is higher, which results in a doubling.

We have a few point of loss in this design, one is the diodes, as you mentioned, but also the rate at which the capacitors discharge. If C1 discharges faster than c2 can charge, and with standard parts this could happen, up to 20% faster, and C2 is always conducting to the next stage, then you could have a situation where C1 is not fully charging C2 in comparison to draw. Since some of this is caused by how long the cycle of discharge, caused by the switching frequency of the IC, there is some fudge range, and 9v does not sound too bad, but not the best and "should" not make a lot of different in volume, but some, as this design is already "quite"

 In a design I have been working on, using the same basic supply http://www.diystompboxes.com/smfforum/index.php?topic=94778.0 (http://www.diystompboxes.com/smfforum/index.php?topic=94778.0) you can see my voltages starting at 9v, at third stage with load I saw 25v.


Looking up your speaker, it looks to be a very inefficient speaker as it is rated for 116db at 150 watts @ .5 meters. Do you have a speaker you can test with? another guitar amp you can just unhook the speaker for a second and test?
The Murder one is putting out less than .4 watts.  (65mw max for that tube and your not going to get half that If I remember correctly)
This is one of those Just Loud enough amps, I love them, great for practice and for recording.

I am on travel till Friday, and I just got my transformers in, just need a voltage drop resistor for the heaters and I will have mine completed. I will measure my voltages and let you know how it comes out. I have an SPL meter and will measure with my efficient Red Coat speaker and my speaker from a Mic stand monitor to see how much difference I get.

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 09, 2012, 08:18:47 AM
Thanks for this further information, iccaros.

The speaker is less than ideal - just what I had lying around for testing purposes.  Something better is in the pipeline, just not here yet!  Will be interested to hear how your build turns out.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on February 11, 2012, 03:27:00 AM
I have a good 68 volts on mine, I just completed today, fried a max 1441.. if you forget to connect the grounds, speaker and transformer, this power supply pushes 15v back to main voltage. . Man that 18R 2watt gets hot.. after 10 min its really hot to touch..
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 11, 2012, 10:09:39 AM
if you forget to connect the grounds, speaker and transformer, this power supply pushes 15v back to main voltage.

Are you saying my speaker shouldn't be a "floating" circuit, but that I should ground the speaker?

Man that 18R 2watt gets hot.. after 10 min its really hot to touch..

Careful with that!  I measured mine at well over 90oC (~200oF)!   :o
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on February 11, 2012, 11:32:36 AM
yes, I believe the speaker should be grounded.. :)
hmmm, will have to recalculate that resistor.. clip a heat sink to it..

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 11, 2012, 03:24:44 PM
Thanks - I shall give that a try...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 12, 2012, 10:57:33 AM
Hmmm...  grounded the speaker, but I can't see it made a whole lot of difference.  Sounded pretty much identical.   :-\
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: zambo on February 12, 2012, 01:54:17 PM
bad speakers will make you rebuild an amp for no reason! Try a different speaker. I have thrown ( given) away about half of my speaker stash cause they just weren't any good.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on February 16, 2012, 02:56:15 AM
Build complete
I measure 69 volts off the OT
Sounds loud enough through my Red Coat Wizard speaker.
Through the 4X12 Marshall is cool
this amp takes pedals well, the tone of the amp stock cranked is OK.. (I understand my speakers will make up 80% of that sound)
After messing with my Wha peddle I think I will do some tone adjust on the next, or maybe not. I say that because with my Govonor pedal this things sounds awesome.. I played it for an hour strait, had to turn off as with that Red Coat it traveled through the house too much at 11pm.

I also hooked it to some very inefficient speakers, and to a EV monitor speaker, its way too under powered to push these inefficient speakers to usable volume. I think this is Blue Bunny's issue.

Will post sound clips tomorrow.

Thanks Rick, fun project.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 16, 2012, 07:54:12 AM
I have a more appropriate speaker in the works, so this sounds encouraging!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on February 16, 2012, 07:48:48 PM
@BB
here are some pictures and some OK sound clips, I did two, the first is with the pre volume @ 5 oclock and master at max. I go back and forth between using pedals and not..
its a wave file so be prepared.. this goes from the stright amp, to using my super-overdrive to the govenor. Wah, Delay and Belton Reverb as needed. 
http://dl.dropbox.com/u/14312589/MOCleanpre%20set%20to%205%20master%20max%20with%20effects.wav (http://dl.dropbox.com/u/14312589/MOCleanpre%20set%20to%205%20master%20max%20with%20effects.wav)
my board
(http://dl.dropbox.com/u/14312589/IMG_20120216_162053.jpg)

the amp, I put it on one of my other amps to show size
(http://dl.dropbox.com/u/14312589/IMG_20120216_082203.jpg)

Last clip is me just jamming with pre gain going form 7oclock to max and back to add effects..
http://dl.dropbox.com/u/14312589/MOCleanpre%20set%20to%207%20master%20max%20with%20effects.wav (http://dl.dropbox.com/u/14312589/MOCleanpre%20set%20to%207%20master%20max%20with%20effects.wav)

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on February 20, 2012, 07:19:13 AM
[ WAVs.  It's a wonder Microsoft don't sell hard disks.  ;) ]

Sounds great - thanks for putting these up.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: snarblinge on February 20, 2012, 04:53:18 PM
Hi Rick, read through all of this finally, and gathering bits together to build one.

what were your reasons for ditching the bias in V7 or reverting back to V5 basically, or am I missing something, I plan to turret this so want to plan it out before I begin.

thanks
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 20, 2012, 06:28:08 PM
V7 is far in advance of V5. V5 had the -ve bias to get cleaner cleans, whereas V7 is set up like a proper tube amp with correct cathode biasing.

I've never experienced the motorboating others have recently noted, but on my next revision of the PCB I'll add the mods mentioned here:

....try cutting the HV trace between C12 and R1/R2 and bridging the cut trace with a 22k resistor. For completeness, also consider adding another 10uF 100v cap between R1/R2 and ground. Basically, cutting the trace, bridging it with the resistor and adding the extra cap is creating a B1 (to the 5672's B+), really you're converting the preamp section to a Superfly preamp.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: snarblinge on February 20, 2012, 06:33:05 PM
thanks man, with keener eyes i could have spotted that, was just looking at the switch and traces..... i'll stick to 7.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: fpaul on February 21, 2012, 08:32:36 AM
Is there a "best" way to secure the tubes to the sockets?  I was thinking of either soldering or hot gluing the outside legs and was wondering what others have used.  I had some problems getting it boxed without a tube falling out.  It's finished now but I don't think the tubes could stand up to much bumping.

I used the version 5 board with 6112/100k plate resistors. 
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on February 21, 2012, 12:53:54 PM
I don't use sockets. I solder them. I've never had one come back yet for re-tubing.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: fpaul on February 21, 2012, 09:55:02 PM
Quote
solder them

Thanks Rick, I'll solder them eventually.  I'm still trying to decide if I want to add cathode resistors/caps on my rev 5 board.  One side looks easy, the other more of a kludge.

I'm liking the little amp.  Put a dirt box in front and it's great for practice without worrying about going deaf or cops showing up.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Jamirox on March 19, 2012, 05:54:40 AM
Hi,

Do someone can post a PCB File other than the .gif of the version  7 ? Because when I print it's always upsized or downsized, I could match the IC pin pitch but it's too much effort if someone has the PCB file in real size :)

Thank You
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on March 19, 2012, 08:25:27 AM
Hi,

Do someone can post a PCB File other than the .gif of the version  7 ? Because when I print it's always upsized or downsized, I could match the IC pin pitch but it's too much effort if someone has the PCB file in real size :)

Thank You

Resize to 48%.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: patrickbrose on April 11, 2012, 11:45:58 AM
I still have not seen an answer to the Power supply question...
Has anyone used a switching power supply for this? Getting a 12v 500ma regulated (or unregulated for that matter) linear supply here in the US is proving to be very difficult. I can get a 12v regulated 1A Switching supply quick and cheap at Rat Shack. But there are no Linear (transformer based) PS anywhere anymore.
-P
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: fpaul on April 11, 2012, 05:45:26 PM
I haven't tried a switching ps but getting a regulated 12 500ma wallwart shouldn't be any problem at all.  Both my local electronics stores have them.  Altex has one you can buy online but it's pricey.  The other store has them cheap but they don't sell online.  Look around, maybe try evilbay.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: derevaun on April 12, 2012, 03:41:41 AM
It won't break anything to try the Switchmode PS; apparently you'll just hear some interference between it and the voltage multiplier.

If you can find a transformer-based wall wart that puts out 13 - 15 volts, you could put a 12v regulator on its output. Just make sure the voltage difference above 12v is higher than the regulator's dropout. Low Drop Out (LDO) regulators are handy for this.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on April 12, 2012, 03:52:33 PM
Hey Patrick. Just read all 20 pages of this thread  :icon_eek:

My build is working. I've got the V7 standard build. Didn't do any pre-amp/power tube thingy.

First on the PS, in the states I had a bitch of a time finding the right PS. First finding a negative ctr made me lose the rest of my hair which I really can't afford to lose so I got a pos ctr, cut it, soldered and back together. The next problem was finding a non switchable one. NEVER did find one so I'm using a switchable one. Results? No oscillation at all, no whine. I got a small hum but very small and no big deal.

My only "issue" I guess is the lack of volume, but then maybe that is the design. I have no way of knowing I suppose. If I put both pots to say 50% I can barely get a sound. Have to crank to 100% max, which doesn't bother me. i just wish I knew for a fact that this is all the volume this circuit puts out. In the back of my mind I keep wondering would a non switchable PS matter or not? Have no idea. I'll still try to find one though and report back any differences if I ever do.

(http://img859.imageshack.us/img859/7048/img1828a.jpg)

(http://img838.imageshack.us/img838/7060/img1824hg.jpg)

(http://img685.imageshack.us/img685/9618/img1840z.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on April 13, 2012, 12:18:06 AM
this puts out less than .4 watts. So the speaker will have a great impact on how loud it is. With my 103db at 1 watt speaker, I can talk over the amp, but its fun to play. At night it is still a little loud but sound carries in my house.

So try a  more efficient speaker and see how that works for you. Nice build by the way
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on April 13, 2012, 08:29:49 AM
Thanks Steve.

I'm runnig it into a brand new 10" Weber DT-10. I have to admit I don't know much about speakers technically. Of course brand new is not the best sound coming from any speaker but from an effeciency standpoint I'm thinking this speaker is fine, or is it a more scientific reasoning as to whether this speaker is or isn't efficient? I guess I'm judging the speaker by it being new and it rocks in my Champ amp I built but I know that may not be accurate for this little puppy amp.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: zambo on April 15, 2012, 12:11:19 AM
speakers have an efficiency rating in db's. I wont pretend i know much about it but i do know this. With a 5 watt amp and an efficient speaker I can play a gig. with an inefficient speaker, the same amp will sound similar but not nearly loud enough. 3 db is a huge difference in loudness. some speaks are 97db and some are 103db. Im sure one of the smart people on here can explain it more gooder but thats the basic idea.  :icon_mrgreen:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on April 16, 2012, 12:04:34 AM
I will try the more gooder explanation  ;D :icon_mrgreen:

inorder to raise 3db in volume you must double your power. Speakers move the cone by use of charging a coil and either being pulled or pushed by the magnet. The efficiency of a speaking is the rating on how much power it takes to push the speaker. so say you have a 5 watt amp and a speaker that is made to have an efficiency of 96db at 1 watt at 1 foot. So putting in 1 watt the meter would read 96db when standing 1 foot away.  So say you change the speaker to 103 db efficient speaker and now measure, the meter at the same distance with the amp putting out the same 1 watt would read 103db, or the same as if you were putting out 4 watts into the old speaker. So without adding any power we made the amp sound louder.

did that make since?
Also the DT-10's according to the website are purposely inefficient. the goal is to get speaker distortion at lower volumes.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: zambo on April 16, 2012, 02:06:01 AM
Yeah that!   ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on April 16, 2012, 09:27:16 AM
I will try the more gooder explanation  ;D :icon_mrgreen:

inorder to raise 3db in volume you must double your power. Speakers move the cone by use of charging a coil and either being pulled or pushed by the magnet. The efficiency of a speaking is the rating on how much power it takes to push the speaker. so say you have a 5 watt amp and a speaker that is made to have an efficiency of 96db at 1 watt at 1 foot. So putting in 1 watt the meter would read 96db when standing 1 foot away.  So say you change the speaker to 103 db efficient speaker and now measure, the meter at the same distance with the amp putting out the same 1 watt would read 103db, or the same as if you were putting out 4 watts into the old speaker. So without adding any power we made the amp sound louder.

did that make since?
Also the DT-10's according to the website are purposely inefficient. the goal is to get speaker distortion at lower volumes.


Makes sense Steve and thanks.

Yeah, I got that speaker on purpose for a little distortion  :icon_lol: Maybe that is not such a good idea for this little amp  ::)

Oh well, I intend to build many more cabs with speakers. I think I'll try this amp in my Fender HRD actually when it comes back from the shop. It is a Weber Thames 12" ceramic. Can't get that thing to break up to save my life!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: zambo on April 16, 2012, 12:24:58 PM
I have used a few stock fender speakers and they always seem to be louder than normal. My blues jr speaker was like twice as loud as anything else i had.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on April 29, 2012, 05:51:35 AM
hey guys i am kind of new here
but i have a question
can i use this output transformer?
http://www.conrad.nl/ce/nl/product/516104/Duplex-spoel-voor-100-V-luidsprekersysteem-0625-125-25-50-10-V/0219400&ref=list

it would be nice
(kind of cheap)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 29, 2012, 05:06:38 PM
I've tried amps with similar transformers - give it a try - nice and cheap!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: karter2000 on May 01, 2012, 08:12:35 PM
Hi all,

I just finished my MO using a kit bought from Rick.  It sounds awesome, even as a bass amp!  I have one question, and I'm not sure it it's stupid or covered before.  If I wanted to use the MO as a preamp or drive another amp, do I need a dummy load similar to a Herzog?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 02, 2012, 12:53:17 AM
Hi all,

I just finished my MO using a kit bought from Rick.  It sounds awesome, even as a bass amp!  I have one question, and I'm not sure it it's stupid or covered before.  If I wanted to use the MO as a preamp or drive another amp, do I need a dummy load similar to a Herzog?
its in ricks drawing on page 17, see the alternative switch added to power out section
http://www.diystompboxes.com/smfforum/index.php?topic=73222.320
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 02, 2012, 02:32:15 AM
Added switch to select preamp or power amp at output socket:

(http://dl.dropbox.com/u/967492/Version%207/M1V7%20Switched%20Pre.gif)

What's happening in the above layout is that the preamp out is taken from lug 2 of the volume control. One half of the DPDT selects either the preamp or the power amp to the output socket. The other half of the DPDT cuts HV to the pentode and the output transformer when the DPDT is in preamp mode - as it's bad for the pentode and transformer to see high voltage without a speaker attached. I'd really stress that caution needs to be taken with this switch, as you don't want to send the power amp output into anything other than a speaker. It's a cool mod though - in preamp mode you've got a massive warm tube overdrive 'pedal' type effect.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: karter2000 on May 02, 2012, 03:29:52 AM
Thanks for the replies guys.  I was thinking it would be cool to tap the output from the transformer, to get the tone of the power section.  Would using a fixed load like the Firezog work?
http://www.aronnelson.com/gallery/main.php/v/DougH/amp/Firezog.gif.html?g2_imageViewsIndex=1
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 04, 2012, 05:41:02 PM
hey
can i replace the 6111 with a pair of 5676 tubes?

pleas i need an fast awnser
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 05, 2012, 03:28:58 AM
hey
can i replace the 6111 with a pair of 5676 tubes?

pleas i need an fast awnser

I guess you could, it would take a redesign, like 1.2v heaters on those and direct heaters, which means .... well there would be a lot of work
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 05, 2012, 03:33:25 AM
could you pleas try
(i have nine 5676 tubes and nine 5672 tubes)

so i need a use for them
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 05, 2012, 05:43:29 AM
which means .... well there would be a lot of work

could you pleas try

This is a DIY forum.

DIY = Do It Yourself

I get emails periodically: "Hey, I've seen your Murder One, can you redesign it for me so I can build it using #### tubes".......kinda wears a little thin.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 05, 2012, 06:42:12 AM
well the problem is
i only use tubes that has a seperate kathode
so i dont know hot to do it with a heater kathode
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 05, 2012, 02:22:05 PM
well the problem is
i only use tubes that has a seperate kathode
so i dont know hot to do it with a heater kathode

you would have to provide 1.2v between pin 2 and 4. This is your cathode and heater. 4 to ground 2 to + 1.2. you are now biased for 1.2v on your grid. get ride of all cathode bias resistors and bypass caps, I do not think there are any in this design, and test.. Bread board first..  you could use a 1N5347B to bring that down the 12v to 2v and do something..

Why did you buy a lot of tubes you had no ideal how to use or a design to test with? I don't have any so I can do no testing. Your biggest issues is getting 1.2v for the heater. As Ricks design is for one tube load at that voltage. You

http://tubedata.tubes.se/sheets/127/5/5676.pdf
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 05, 2012, 04:54:44 PM
i got them for free
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: jbgron on May 05, 2012, 06:32:09 PM
???
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 05, 2012, 06:35:05 PM
i have re counted them the 5676 i have 38 of them
so i am kindof not knowing what to do with them

and wow so easy to djust it for this tubes!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on May 10, 2012, 10:02:15 AM
Might I suggest selling those tubes, taking the money and buying some that will work for this cirucuit.

The DIY community is a great community of helpful people, but asking someone to basically build part of a circuit for you because you have some free tubes is pushing the envelope. If it was me, and for the sake of discussion here, had I wanted to ask this, I would have offered a bunch of those tubes as a gesture of reciprocation for someone to spend this kind of time or something.

But hey, that is just me  :icon_mrgreen:



With respect to the build and for what it is worth, the TC1044 sounds better to my ears in this. Could be my mind telling me it should so it does, but I guess perception can become reality. My signal keeps going out though and then comes right back. And I thought I had experienced all symptoms of screw ups. But alas, this is one I have not so I have to figure that one out.
Title: Re: Sv: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Perrow on May 10, 2012, 12:17:31 PM
i have re counted them the 5676 i have 38 of them
so i am kindof not knowing what to do with them

and wow so easy to djust it for this tubes!

Send five to FC, wait a while and he'll post a layout ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 18, 2012, 05:56:12 PM
give me the adress
i will send 8 of them
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 23, 2012, 02:38:05 PM
well i did a DIY
i have a 1M to ground as a bias
and used my 5676 tubes

and also i used the output transformer i asked about

here it is
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 23, 2012, 05:17:08 PM
sounds good..
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 23, 2012, 05:24:54 PM
it lacks a little base
but a good box shall fix that

now to get a battery that fits the box i have made (yes custom box for amp and speaker)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 23, 2012, 05:41:08 PM
Nice youtube. Well done for DIYing.  8)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: robot797 on May 23, 2012, 11:02:55 PM
thank you
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Joe Kramer on May 27, 2012, 10:12:44 PM
Hey Friends,

Looks like a great project, love the simple elegance of the design.  I'd like to try building one of these to power a small speaker cabinet I've got.  After reading through most of the thread, it appears Version 7 is the most up-to-date revision of the circuit, but I don't see the schemo for it here.  May I ask that someone post or link to it here? 

Many Thanks!
Joe       
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 28, 2012, 02:13:03 AM
I do not believe anything has changed since this page http://www.diystompboxes.com/smfforum/index.php?topic=73222.260 (http://www.diystompboxes.com/smfforum/index.php?topic=73222.260)

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Joe Kramer on May 28, 2012, 03:06:16 PM
Thanks Steve.  Version 6 looks good, but I still have a few question regarding Version 7, which has a layout but not a schemo:
This is the layout I've been using for a while, verified. Version 7 - I'm such a tweaker. It dispenses with the bias switch and associated circuitry. It also includes (orange) pads and swiching diagram for adding a pre-out using the existing speaker out socket - it basically takes a tap from the preamp stage and also cuts power to the pentode when switche to pre-out mode. If you dont want the pre-out switch you'll need to jumper the orange pads together.

BTW, it's easy to build teh Modder's Delight without the bias switch, just a matter of not using a few components and wiring it slightly differently.

My question is, what are the changes in the "few components and wiring" regarding the bias switching for Version 7?  Since I intend to do my own perfboard layout, a complete schemo of V7 would save me from having to reverse engineer the stripboard layout.

Thanks,
Joe
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on June 01, 2012, 01:17:43 PM
Hey Friends,

Looks like a great project, love the simple elegance of the design.  I'd like to try building one of these to power a small speaker cabinet I've got.  After reading through most of the thread, it appears Version 7 is the most up-to-date revision of the circuit, but I don't see the schemo for it here.  May I ask that someone post or link to it here? 

Many Thanks!
Joe       

Joe, here is a thread you might find useful.

http://circuitworkshop.com/forum/index.php?topic=1046.0
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Joe Kramer on June 01, 2012, 02:05:11 PM
Excellent--thanks Blueshawk!  I'll study a bit, and then probably come back with a few questions. . . .

Thanks again,
Joe 
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: c3tester on July 03, 2012, 05:21:20 PM
TNBluesHawk:

I've been off the grid for a while, but I received a PWB from Rick a while ago and I've finally started the Murder One build.  Thanks for all the previous tips on assembly of the board ...made it go smooth and quick.  I saw you wired an on/off switch to your Murder One.  I don't have that on Rick's schematics anywhere, did you have to put any drop-down resistor in series with the led?  How did you wire that circuit?  Thanks.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on July 10, 2012, 04:30:39 PM
Hey C3. I just happened to click into this. Rather than go off my memory exactly let me get home and look at my wiring. I did use a CLR in series with the LED for sure. Trying to remember the rest though. It was a DPDT of course and I just wired middle and end lugs leaving one end empty.

I'll post up tonight.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on July 10, 2012, 07:58:50 PM
Hey C3 here is the deal.

DPDT

Top row of lugs
Left lug: wire to 12v pad on PCB   
Right lug: CLR/LED pos leg of LED

Middle row of lugs
Left lug: Just jumper to the right lug
Right lug: run wire to 9v on DC jack

Bottom row of lugs: leave both empty.

One thing however. I think I put this in this thread, and not the one at Circuitworkshop. The only problem I have with my build is I get an intermittent signal. So I'll be playing and then the signal goes out...then it come back...then it goes out etc... I tried some quick troublshooting but can't find that issue. Whether or not it is tied into me wiring this DPDT wrong I don't know as I think it is correct. But, just an fyi.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tom42107 on July 17, 2012, 07:52:33 PM
Hello group. Just wanted to say hey and post a pic of my nearly completed "Murder One" amp. Here it is right before I put in the tubes. (Not sure about those knobs yet :)).

(http://img266.imageshack.us/img266/3042/littleguitaramp.jpg)

I'll post after I fire it up. Thanks (Frequency Central), for such a cool little amp.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on July 19, 2012, 09:34:52 AM
That thing is so cute I could hug it   :icon_lol:

I love the knobs actually.

Any gut shots?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tom42107 on July 19, 2012, 09:30:51 PM
Here's a few more picts. Not the prettiest inside but if I ever make another I'll know just what to do. Gonna fire it up this weekend, (just slammed at work).

(http://img840.imageshack.us/img840/4641/imag0120zv.jpg)
(http://img21.imageshack.us/img21/1925/imag0118ct.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on July 20, 2012, 05:06:07 PM
Shoot, looks great to me!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tom42107 on July 20, 2012, 10:59:32 PM
Thanks a lot TNblueshawk. What part of TN are you in?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: TNblueshawk on July 24, 2012, 11:42:04 AM
Specifically Hermitage, about a 15 minute drive east from Nashville.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tom42107 on July 28, 2012, 11:17:28 AM
I'm in Knoxville. The reason I ask is because I was thinking of starting a DIY audio club. I think it would be a great way to learn more about all this stuff we love to build.

Tom
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Maik on August 25, 2012, 06:49:17 AM
On V7-how can I use both signals. My idea is: preamp to my Line6 X3L for fx and the signal from the transformer to a speaker. Cheap 3-way amping  ;D
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 25, 2012, 10:11:09 AM
On V7-how can I use both signals. My idea is: preamp to my Line6 X3L for fx and the signal from the transformer to a speaker. Cheap 3-way amping  ;D

Take a pre out from one of the lugs of the volume pot, lug 2 if you want the volume to attenuate the pre out, or lug 3 if you don't.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Maik on August 26, 2012, 08:17:38 AM
OK, it will work! Great. Thanks  ;D
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gretsch61 on August 26, 2012, 11:00:57 AM
Hi,

HELP NEEDED!  ;D

I was wondering what kind of Indicatorlight (LED???) is used and where it would be connected.

cheers,

gretsch61
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 26, 2012, 11:18:05 AM
Power/LED:

12V from DC socket >>> SPDT lug 2

SPDT lug 3 >>> LED (via 1K resistor) and PCB
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gretsch61 on August 26, 2012, 11:50:41 AM
Thx for your quick reply, Rick!

What is the the actual size of the PCB and the enclosure now with Version 7?

cheers & greetz from germany!

steve
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gretsch61 on August 26, 2012, 12:14:42 PM
Power/LED:

12V from DC socket >>> SPDT lug 2

SPDT lug 3 >>> LED (via 1K resistor) and PCB

...where should I connect the LED on the PCB?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Maik on August 26, 2012, 12:57:11 PM
Hey Steve
einfach auf 12V+, wie bei jeder Stompbox.

edit ok, ignorieren. Wenn´s Rick sagt...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 26, 2012, 12:58:00 PM
...where should I connect the LED on the PCB?


Nowhere.

Connect LED anode to SPDT lug 3 (via 1K resistor), connect LED cathode to DC socket ground.

Connect PCB +ve input to SPDT lug 3, connect PCB ground to DC socket ground.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gretsch61 on August 26, 2012, 03:23:18 PM
...where should I connect the LED on the PCB?


Nowhere.

Connect LED anode to SPDT lug 3 (via 1K resistor), connect LED cathode to DC socket ground.

Connect PCB +ve input to SPDT lug 3, connect PCB ground to DC socket ground.

Hi Rick,

is there a SPDT that you would recommend for this? Also, what kind of Switch do you use for the S1 in the switched preamp mode?
Would it be something like this:

(http://www.tube-town.net/ttstore/images/product_images/original_images/4053_1.jpg)

Would you be able to point out, where the "+ pin" of the Caps would go on the PCB Layout?

The CAPS: C2, C4, C6, C8, C10, C12, C15, C16 and C19 the "- pin" will connect to the "GND"
But how about CAPS: C1, C3, C5, C7, C9, C11, C13 and C14?  Where does the "+ pin" connect to?



Maybe there is a schematic for your Murder One V7

many thx and cheers,
Steve


U-P-D-A-T-E:

Ok, I have figured out the polarity of Caps C1 to C12 and C15,C16,C19
The only ones missing are the 0.1uF Caps do they need to be soldered
with a special polarity or is the polarity of these Caps of no importance?



Title: Question about 5672 Submini Pentode and 6111 Dual Triode
Post by: gretsch61 on August 27, 2012, 05:22:04 AM
Hi Everyone,

I was wondering wether it would be possible to change the two tubes (5672 Submini Pentode and 6111 Dual Triode) for some tubes that would use a "normal" tube-socket. If so, which ones would I be able to use (without loosing functionality)?
I have found something like this for the 5672 Pentode http://www.conrad.de/ce/de/product/157385/Roehre-Elektronenroehre-5672-DL-652-Pole-5-Sockel-Subminiatur-Beschreibung-Subminiatur-Pentode (http://www.conrad.de/ce/de/product/157385/Roehre-Elektronenroehre-5672-DL-652-Pole-5-Sockel-Subminiatur-Beschreibung-Subminiatur-Pentode)

Would there be something like this for the 6111 Dual Triode too?

cheers & thx,

gretsch61
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on August 27, 2012, 06:22:49 AM
first to come to mind would be a 12au7 or 12ax7 for the 6111
I don't know what your link is showing for the 5672 as the picture looks like a EL34 or a 6L6 not  a 5672, but any small pentode could take its place, 6au6 for example

If its just sockets your are looking for

There were sockets for subminature tubes, but I find they go microphonic when they can move around, I suggest you just solder them. but here are some sockets http://dhost.info/mhdtlab/socket.htm
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gretsch61 on August 27, 2012, 07:05:05 AM
first to come to mind would be a 12au7 or 12ax7 for the 6111
I don't know what your link is showing for the 5672 as the picture looks like a EL34 or a 6L6 not  a 5672, but any small pentode could take its place, 6au6 for example

If its just sockets your are looking for

There were sockets for subminature tubes, but I find they go microphonic when they can move around, I suggest you just solder them. but here are some sockets http://dhost.info/mhdtlab/socket.htm

Thx for your quick reply! Will a 12au7 or 12ax7 (do they have 8-Pins? I think they have 9???) work with the Voltage supplied by this Layout?
The 5672 says its a subminiature pentode...
I would really like to use socket, cause I would do some cosmetic to the look of the Amp and
use something like this (http://www.tube-town.net/ttstore/images/product_images/info_images/1423_0.jpg) to protect
the tubes.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gretsch61 on August 27, 2012, 08:26:15 AM
Nice. 6112 is like twice the gain of 6111. It will require higher anode resistors ( R1, R2 - try 100k) and probably a higher value grid stopper ( R12 - try 470k).

If it still motorboats after changing those value, try cutting the HV trace between C12 and R1/R2 and bridging the cut trace with a 22k resistor. For completeness, also consider adding another 10uF 100v cap between R1/R2 and ground. Basically, cutting the trace, bridging it with the resistor and adding the extra cap is creating a B1 (to the 5672's B+), really you're converting the preamp section to a Superfly preamp.

BTW, I've got a few spare etched PCBs and tube sets if anyone wants one.


I use 120 K Ohm for R1/R2 and 510K for R12, also applied C12 and 10 µF. The sound is much better, "motor boating" can be eliminated, if I crank it can be very cool. Now I come to the next problem, the sound is cutted earlier as I expect, i.e. if I pick string E Low, the "sustain" is stopped much earlier (even earlier than a Django style guitar). After picking a string the sustain makes hingher volume and suddenly (millisecond) niose and than stop. Any suggestion? Bad tube maybe ?
Regards


Hi Rick, hi Blackface,

would this be the right Layoutchange for the 6112-mod?
http://s7.directupload.net/file/d/2995/h8er95ir_gif.htm (http://s7.directupload.net/file/d/2995/h8er95ir_gif.htm)

cheers,
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on August 27, 2012, 10:46:25 PM
first to come to mind would be a 12au7 or 12ax7 for the 6111
I don't know what your link is showing for the 5672 as the picture looks like a EL34 or a 6L6 not  a 5672, but any small pentode could take its place, 6au6 for example

If its just sockets your are looking for

There were sockets for subminature tubes, but I find they go microphonic when they can move around, I suggest you just solder them. but here are some sockets http://dhost.info/mhdtlab/socket.htm

Thx for your quick reply! Will a 12au7 or 12ax7 (do they have 8-Pins? I think they have 9???) work with the Voltage supplied by this Layout?
The 5672 says its a subminiature pentode...
I would really like to use socket, cause I would do some cosmetic to the look of the Amp and
use something like this (http://www.tube-town.net/ttstore/images/product_images/info_images/1423_0.jpg) to protect
the tubes.


they would work at these voltage, at about 80volts you get good reaction from the 12XX7 types..  I do like those protectors
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: gretsch61 on August 28, 2012, 03:14:05 AM
Quote

they would work at these voltage, at about 80volts you get good reaction from the 12XX7 types..  I do like those protectors


okay, but how about the number of pins? would I have to do a redesign of the tubesection? The difference between the 6111 and the
12au7 is PIN9 which would be the "Heater Center tab". How would I have to modify the design of the MurderOne to fit the 12au7?

On the 6au6 its a little different! The 7 pins are:

1: Grid No.1                            
2: Grid No.3, Internal Shield      
3: Heater
4: Heater
5: Plate
6: Grid No.2
7: Cathode

while the 5672 Pentode (5 Pins) is like this:

1: Plate
2: Grid No.2
3: Filament (Heater), positive
4: Grid No.1
5: Filament (Heater), negative: Grid No.3

so we are missing out on the Internal Shield and the Cathode. Any Suggestions?  ???





Title: Re: Murder one Tonestack???
Post by: gretsch61 on August 28, 2012, 03:17:11 AM
Hi Everyone,

would it be possible to add a tonestack to the MurderOne?

E-D-I-T:

I have found a schematic, that would bring a Tonestack to the MurderOne:

This would do the Job...

(http://img5.fotos-hochladen.net/thumbnail/tonestackdiezwxsb2cjgt1v_thumb.jpg) (http://www.fotos-hochladen.net/view/tonestackdiezwxsb2cjgt1v.jpg)



thx for any help!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Maik on August 30, 2012, 07:20:43 AM
Hi,
I want a blender before the speaker out. It should not affect the preamp out.
http://tagboardeffects.blogspot.com/2012/02/split-n-blend.html#links

This is how I want it...
http://img198.imageshack.us/img198/2493/miniampblend.jpg

Where is the point to put the blend in?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Maik on August 31, 2012, 06:33:59 AM
Rick???
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Magnus on August 31, 2012, 01:18:52 PM
Hello,
I am building the Murder One right now and I have a question:

The 6111-Tube starts with Pin 1 soldered to the quarter on the pcb,
then Pin 2, 3 and 4 are soldered from left to right next to the quarter
and Pin 5 starts above Pin 4, following Pin 6, 7 and 8 from right to left - correct?

...hope you understand my definition  ;)


Greetings
Magnus
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 31, 2012, 02:13:45 PM
Hello,
I am building the Murder One right now and I have a question:

The 6111-Tube starts with Pin 1 soldered to the quarter on the pcb,
then Pin 2, 3 and 4 are soldered from left to right next to the quarter
and Pin 5 starts above Pin 4, following Pin 6, 7 and 8 from right to left - correct?

...hope you understand my definition  ;)


Greetings
Magnus

Correct, just like an 8 pin DIL.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on August 31, 2012, 02:22:58 PM
Hi,
I want a blender before the speaker out. It should not affect the preamp out.
http://tagboardeffects.blogspot.com/2012/02/split-n-blend.html#links

This is how I want it...
http://img198.imageshack.us/img198/2493/miniampblend.jpg

Where is the point to put the blend in?

I'd try between the two preamp stages. After C13, before the gain pot. Maybe.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Magnus on August 31, 2012, 04:00:45 PM
Thank you Rick,
yes 8 Pin DIL, why didn't I explain it this way - could be much easier ::)

Today I got my 6111-Tube, now I'm waiting for the enclosure, wallwart and knobs...

...just can't wait to build and hear it  8)

So here's a picture of the finished "vintage-style" pcb:

(http://img268.imageshack.us/img268/2162/murderonev7.jpg?http://imageshack.us/)


Greetings
Magnus
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on September 02, 2012, 07:15:14 PM
Quote

they would work at these voltage, at about 80volts you get good reaction from the 12XX7 types..  I do like those protectors


okay, but how about the number of pins? would I have to do a redesign of the tubesection? The difference between the 6111 and the
12au7 is PIN9 which would be the "Heater Center tab". How would I have to modify the design of the MurderOne to fit the 12au7?

On the 6au6 its a little different! The 7 pins are:

1: Grid No.1                            
2: Grid No.3, Internal Shield      
3: Heater
4: Heater
5: Plate
6: Grid No.2
7: Cathode

while the 5672 Pentode (5 Pins) is like this:

1: Plate
2: Grid No.2
3: Filament (Heater), positive
4: Grid No.1
5: Filament (Heater), negative: Grid No.3

so we are missing out on the Internal Shield and the Cathode. Any Suggestions?  ???






Sorry I took so long, I missed your reply.


With the miniature your right, the cathode is part of the heater,  but with  a non directly heated tube like 6au6 or the 12ax7 you have to add a resistor to ground for a bias, Rick has already done that with the 6111, which is a good starting point. But the pins are different, but if your using a socket that should be easy to change.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tom42107 on September 04, 2012, 09:59:40 PM
So, I'm having some trouble with my MO.

http://www.diystompboxes.com/smfforum/index.php?topic=73222.msg859500#msg859500

Not sure how to describe it. When I take some voltage readings it seems to be stable with both knobs turned all the way down, but when I turn the knobs all the way up, it seems to become unstable. For instance, the voltage coming out of the charge pump is a stable ~75vdc, but when I turn the knobs up, it bounces from 73v to 81vdc, back and forth. I've swapped out the 7660s with a 1044 and it doesn't change. When I plug it up it just doesn't sound right. Here are some of the voltage readings I'm getting with the knobs  down and unplugged from speaker:

6111
Pin 1 - 38V
2 - 3.6mV
3 - 6.6V
4 - 1.23V
5 - 1.32V
6 - 5mV
7 - (-10mV)
8 - 34.7V

5672
Pin 1 - 64.5V
2 - 75.3V
3 - 1.61V
4 - 4.4mV
5 - 4.8mV

The 5672 never really gets hot, in fact, I can't really see it glow. Could it be bad? Thanks.

Tom
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tom42107 on September 04, 2012, 10:15:09 PM
Sorry, I should have mentioned that this is V7 with the switched pre out.

Tom
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on September 05, 2012, 05:46:37 PM
Tom
do you get audio through?

your voltages look OK, at least workable, I do not remember what the plates on the 6111 should see.

Voltage will fluctuate as current is passed through the tube, as for
"he 5672 never really gets hot, in fact, I can't really see it glow. Could it be bad? "
no this is normal with this tube..
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tom42107 on September 06, 2012, 10:22:01 AM
iccaros, yes, It does pass audio. The problem may be I just don't have anything to compare it to. I feel that it doesn't sound right. Do I need to lift the 1/4in. jacks off the case with isolating washers? Thanks for your help.

Tom
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Magnus on October 13, 2012, 08:28:24 AM
Hello,
I am building my Murder one (V7) now, but I don't know if I have done anything right on the offboard wiring...
The volume is a little bit low, so probably theres an error in my (ground-)wiring
or maybe it is ok for a small amp like that (connected to a 1x12 box), I don't know...

btw: The amp is running, but there is a big problem:
The IC, the non-polarized caps and some Electrolytics get really hot  :-[

- Where do the ground connections from the pcb exactly go to and where do they meet?
(would be nice to explain it, I am not sure if I have done them all right)

- Do I have to connect the grounds from both jacks together and to the enclosure (they are isolated ones)?

So after much builds that worked at the first try it was time to get problems  ;D


Greetings
Magnus
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on October 14, 2012, 11:38:06 AM
The IC, the non-polarized caps and some Electrolytics get really hot  :-[

You might find that this is the 18R drop resistor for the first valve's heater.  Mine got incredibly hot and was heating up everything else close by.  I chickened-out and externalised mine to avoid a fire or a meltdown or something worse...

- Where do the ground connections from the pcb exactly go to and where do they meet?
(would be nice to explain it, I am not sure if I have done them all right)

- Do I have to connect the grounds from both jacks together and to the enclosure (they are isolated ones)?

Yep, join all the grounds together, including the output jack, and connect to the enclosure (perhaps via the input jack screen, or one of the bolts holding the OT).
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: BurgerFactory on October 15, 2012, 08:48:45 AM
Hi Guys,
 I am new to this sight in registration only. I have built many projects with the help and genius of some threads from this sight. Yesterday I finished a version of Rick Holts Murder ONE. I used a 12AT7 for the Pre amp and a 5672 for power. A 7660 for the pump and some messing around and reconfiguring and the thing sounds amazing. I just wanted to say that this is a brilliantly simple and effective design and I can't thank Rick and all of you DIYSB members enough for posting all of the info you have on this and many other topics. I do Instrument amp repairs out of my house and have always wanted a low wattage tube project. I have been building my own effects for years but havn't tackled the amp world until now. Partially from sickness of looking at them all hacked to hell all the time lol, and mostly from lack of effort on my part to create a good design. Anyway blah blah blah I feel guilty for susing the s#$t out of this sight and not contributing so here I am and I will post some pics and clips of this little amp as soon as I can.

Cheers,
Troy
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: c3tester on November 21, 2012, 11:08:43 AM
Quick shout out to TNBluesHawk (and others that have provided patient guidance).  I finished my first M1 build (prototype)  a month or so ago.  Learned tons, and I've got some fixes to incorporate into the finished product.  Distorted sound is great, clean sound is kind of muffled and maxing both gain and volume produces a kind of tremolo effect.  Got some investigating to do.  Thanks for all your help.  I'll try to post a pic. :)


...just tried.  Can't figure out how to attach a picture.  Sorry.


Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on November 21, 2012, 11:38:15 AM
Check out this piece of advice (http://www.diystompboxes.com/smfforum/index.php?topic=73222.msg832199#msg832199) given to me by sadcakes (which Rick had previously mentioned earlier in the thread).  I also had "tremolo", but this small mod got rid of it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: c3tester on November 28, 2012, 06:32:00 PM
Thanx BlueBunny.  Sounds like what I might need ...I'll give it a try.  Had some hum, but switched power supplies and things are quiet as can be.  Seemed to help a little with oscillation too (has a little lower avg output).  Great little amp.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ibanezsr500 on March 09, 2013, 01:11:19 AM
Hey guys,

Alright, I've got one of these built and wired up, but I'm having a few problems.

Problem no.1: I'm not getting the full 80V at B+, it's currently reading 46V, nowhere near close. The power supply is reading 12V, and the voltage increases are happening in a consistent fashion (ie. all stages are increasing the voltage by x, I haven't got the exact numbers in front of me at the moment, but all the stages seem to be working as intended). Also, the Maxx1044 is getting hot, I can't keep my finger on there for more than a few seconds. And, the caps that are handling the higher voltages are getting warm, but not so much that I can't touch them. Te actual PCB surrounding these caps is getting hot also, but I'm assuming that the heat is transferring from the caps onto the board. And yes, the caps are rated for 100V.

Second problem, which may be related to problem no.1, I'm getting a fuzz factory-esqe occilation when the gain is cranked, but the volumes backed off to about 3/4. I'm also getting the motor-boating people were having issues with earlier in the thread when both the gain and volume are dimed. I haven't yet deviated from the layout, so all values are exactly the same as Ricks V7 layout.

Now, I'm currently using a switchmode regulated power supply. I can't find a non-switchmode one for a reasonable price here in Aus, let alone a place that sells one.

Any help would be appreciated. I've checked the board for shorts, dry solder joints etc, but I can't find anything that would be causing me to have these problems. Except the power supply, would it be the reason that I'm not getting full voltage?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on March 09, 2013, 09:10:13 AM
I was never getting the full 80V in mine either (more like 68V?).  Different diodes might help - Schottkys with lower drop.  I didn't try this 'cause I couldn't be ar5ed with swapping 'em all out.

I also found my 7660 getting hot.  (BTW, the max. input voltage for the 1044 is only 10.5V.)  But I think it was more to do with the voltage dropping resistor sitting close by.  This was reaching boiling point and heating up everything in the vicinity!  I "fixed" this by bolting a 10W resistor to the outside of the case!

Check out the motorboating fix - mentioned in my post about three entries back.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Ibanezsr500 on March 09, 2013, 03:33:54 PM
Ok cool. Thanks. I ruled out the power supply, as I was able to run the amp off a 12v battery I had laying around.

Yeah, I figured that the max1044 was getting hot from the 12V, I didn't realize that it would get that hot though! I'm getting a reading of 90 degrees Celsius! And that's not even the hottest part of the board, the 2W resistor is getting up to about 120 degrees Celsius. The diodes and caps are around 80 degrees as well. Are these normal temperatures? That's pretty freaking hot for something mounted in an unventilated metal box...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on March 10, 2013, 11:47:47 AM
That's pretty freaking hot for something mounted in an unventilated metal box...

Uh huh.  I'd ventilate the box.   ;)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Thecomedian on March 10, 2013, 04:11:15 PM
heat sinks are pretty nice too  :icon_wink:
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on April 27, 2013, 11:55:41 PM
My latest Incarnation of the murder one..  Still need to stain and polyurethane, and then final test once put back together..

(https://dl.dropboxusercontent.com/u/14312589/Murder_one_wood.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on April 28, 2013, 06:20:11 AM
Still enough intetest in this project for me to have a run of fabbed, screenprinted and soldermasked PCBs made?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: wgc on April 28, 2013, 03:12:26 PM
I'd be interested in a pcb
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Maik on April 29, 2013, 02:27:34 AM
me too
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 01, 2013, 12:33:53 AM
Rick, what would the cost on those be?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 01, 2013, 03:39:58 PM
Rick, what would the cost on those be?

Same as the etched ones I've been doing, around Ł12 GBP.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 01, 2013, 04:52:37 PM
I would be in for at least 2.. these are popular gifts for friends.. my next one will be covered in Shag Carpet..
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Scruffie on May 01, 2013, 08:45:06 PM
How would the PCB be designed? Board mounted jack, switches and pots? Just the same as the original layout? etc.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: frequencycentral on May 02, 2013, 02:45:33 PM
How would the PCB be designed? Board mounted jack, switches and pots? Just the same as the original layout? etc.

I'd just thought same layout as my original etched PCBs, but fabbed, silkscreened and soldermasked. That way it would fit 1590B as in my production numbers, as well as being friendly to those who wanna go with other form factors. Open to ideas though. I guess PCB mounted 9mm alphas would work well. Though going the whole way and having everything PCb mounted would make it impossible to build in a 1590B.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 03, 2013, 12:44:10 AM
IT would, but after building 3 of them, I like more space. It cool to do it small, but I find that the 1 watt and 2 watt are really close to other parts, if you made a version that had mounted pots, it would be nice to open up the layout, maybe add a second pentode.. or at least space.. but its your design, either way I can make work.

In my current build I am getting a tremolo effect when all pots are dimed out..  its hard to get probes in between some parts to trouble shoot..


Note, the above is just my opinion, not meant to give advice or fool people into believe I have any real knowledge.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on May 03, 2013, 04:23:57 PM
@iccaros: check this out for a tremolo fix:

Check out this piece of advice (http://www.diystompboxes.com/smfforum/index.php?topic=73222.msg832199#msg832199) given to me by sadcakes (which Rick had previously mentioned earlier in the thread).  I also had "tremolo", but this small mod got rid of it.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 04, 2013, 12:27:06 AM
thank, I am on that route, I replace all the tubes, and tried a bigger grid stopper, but not the load resistors, I was going to rebias, I know its oscillation from high gain, I can see it on the oscope, so next I will go with load resistors, I Am also may change c14 to a  .022 as this time its sounding a little dark
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: iccaros on May 04, 2013, 01:41:09 AM
Plat resistors worked, not sure why, are we not increasing gain with 100K?.. any case, I think I will bring them down to 68K and try that, they are a little farty.. I think 68K is what I used before.. hope to have sound samples soon.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Jdansti on October 02, 2013, 01:14:55 AM
Clean Mod

I know this is an old thread, but I thought people would want to know about this.

I've had an M1 board sitting around for a couple of years and finally got some time between honey-do projects to build the amp. It sounds good, but needs some tweaking. I don't know if this is the same thing that others have experienced, but it's kinda farty when the volume is close to max. I've done the resistor mods and it's helped, but maybe I need to increase the resistor values more.

The other thing I've read is that it doesn't get very clean. I've discovered an easy clean mod by accident. When I first fired it up, all I could get was clean, and when I turned up the gain, the volume decreased down to nothing at full gain. After trouble shooting, I found a solder bridge between R1 and R2 where they connect to the 6111 anodes. After fixing that, the amp behaved normally. As a test, I shorted the two resistors with a clip, and I got the nice clean sound again. The only thing is you have to turn the gain down or you'll lose volume. I placed my DIY Landgraff Dynamic Overdrive in front if it with the resistors shorted, and the volume went way up and sounded great. I plan to install a SPST across the resistors to act as a clean/dirt switch.  Sorry if this is already common knowledge.

Photos:
http://www.diystompboxes.com/smfforum/index.php?topic=36392.msg937986#msg937986
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: thomasha on October 02, 2013, 12:24:20 PM
that sounds like local negative feedback, and gain controls the amount of signal been amplified that produces the feedback.
Maybe that's why the gain needs to be at low settings.
Merlin has something about it: http://www.valvewizard.co.uk/localfeedback.html (http://www.valvewizard.co.uk/localfeedback.html)
I used NFB from OT to cathode and it works too.
About the farty sound, I reduced the coupling caps to 4.7 nF , and put a 470 pF cap across the grid stopper. That made things sound better IMO.
Nice build btw  ;D

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Jdansti on October 02, 2013, 12:56:39 PM
Thanks, Thomasha. I might try that cap mod if I can get to them. I hot glued the pentode tube to a few components to keep it from moving around (it doesn't get hot like the 6111). I'll see if I can safely remove the hot glue.  Either way, I can at least place a cap across the grid stopper as you suggest.

BTW, I just did a little research on grid stoppers and ran across this article that you might find interesting and informative:  http://www.aikenamps.com/InputRes.htm

Thanks for the tip and welcome to the forum!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: AJDbass on January 09, 2014, 04:53:35 AM
Hi,

Thanks for sharing this great design. Really great project for starting with the build of tube amps. Sorry, I know this is a old thread, but I have a few question regards the PSU.

I build this design, but was wondering about the PSU ampere rating. I read a 500mA regulated AC-DC wallwart is commonly used. I tried my design with a cheap 12V AC-DC wallwart wich is probably non-regulated, and the amp didn't work too well. When the volume/gain knobs are at 3 o'clock, the amp has this weird tremolo effect (it is called motorboating right?). I also have a tiny computer cooler van paralel on the power jack wich consumes 0,08 mA.

So I assumed the circuit didn't get enough amperes to work right. I found another 12v regulated PSU but this one delivers 2,5 A. I tried this one, and it immediately worked and soundend better, but that lasted for about 10 seconds before the amp didn't work anymore. I found out the 17660S IC crashed (got really hot and smelled a bit). So I guess it's not a great idea to use a 2,5 A PSU? I always thought the circuit only gets the amount of amperes it uses and I know the IC is rated for at least 13v.

Thanks
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on January 09, 2014, 08:40:21 AM
You're right: PSUs don't push out amps; circuits draw what they need.  So a 2.5A PSU won't hurt the circuit.  However, if your PSU is unregulated, then it could be putting out way more than 12V - enough to upset the 7660.

Check out one of my own queries further back in the thread concerning the motorboating phenomenom.  There's an easy fix for it (you just sub a couple of parts).
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: AJDbass on January 09, 2014, 10:51:37 AM
Quote
You're right: PSUs don't push out amps; circuits draw what they need.  So a 2.5A PSU won't hurt the circuit.  However, if your PSU is unregulated, then it could be putting out way more than 12V - enough to upset the 7660.
Thanks, I can safely use this PSU then. It's regulated and quit, stays nice at 12.0 volts at my voltmeter.

Quote
Check out one of my own queries further back in the thread concerning the motorboating phenomenom.  There's an easy fix for it (you just sub a couple of parts).
I did read about fixing the motorboating phenomenom, but the motorboating disappeared after using the 2.5A PSU in stead of the cheap unregulated 500ma PSU I used. Unfortunatelyt short after using the new PSU the 7660 died on me. I've got a couple of 7660 IC's on my way, can't wait to try it again.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: tonyharker on January 09, 2014, 03:02:43 PM
Unfortunately some 7660s esp the ICL ones crap out at 10.5v so running them on 12v will destroy them.

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on January 09, 2014, 03:30:59 PM
Unfortunately some 7660s esp the ICL ones crap out at 10.5v so running them on 12v will destroy them.

Isn't that the MAX1044 you're thinking of?  Datasheets for both Harris and Intersil 7660s suggest a nominal 1.5V - 12V working range, with 13V quoted as the absolute upper limit.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: derevaun on January 10, 2014, 01:54:51 AM
It could have hit it with more than 13v. If it's rated for 12v at 2.5A, it would push more than 12v when the current load is lower.

I'd make a regulated supply by using a 15v supply with a 12v regulator.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: AJDbass on January 10, 2014, 03:10:06 AM
I just noticed I used a ICL7660CPA, not the 7660s. The ICL7660CPA is rated at max 10v  : :icon_rolleyes:

The IC's I just ordered are the intersil ICL7660S CPAZ, with a working rate between 1.5 - 12V, so I think those should be fine.

Quote
It could have hit it with more than 13v. If it's rated for 12v at 2.5A, it would push more than 12v when the current load is lower.

Thanks for the input. I've used a voltmeter to measure the voltage with and without load; it stays at 12.0v most of the time and the max voltage I read was 12.4v. I think I can safely use this PSU. I will find out when the new IC's arrive. It could take 2 - 3 weeks so I have to be patient   :(
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Jdansti on January 10, 2014, 08:24:18 AM
The voltage might be different with no load vs a load. Maybe the multiplier chip causes the PS to behave differently than it would with a purely resistive load.

Or maybe I don't know what I'm talking about! ;) Just throwing it out there that these PSs sometimes behave differently when disconnected from the device you're powering.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: AJDbass on February 05, 2014, 04:19:51 AM
Hi there,

A few days back the ICL7660S IC's finally arrived. I replaced the bad ICL7660CPA and noticed that this new IC doesn't even get warm, even after more than an hour. So that's a good thing. The bad thing is that I still had the motorboat thing going on. I tried the resistor mods and the motorboating now starts a little later when turning up the volume and gain, but it's still there. I could place a small resistor at the pots so they act like they can't be turned up all the way, but I will lose some volume.

I do get the feeling that there's a little more going on. I think the amp is a little quiet compared to some clips I saw on youtube, but of course it's hard to be sure. I am using a speaker with a decent efficiency. I implemented the preamp switch, and in preamp mode there is no motorboating whatsoever. Works great as a cleanish boost/overdrive.

Anyway, It is a really fun little amp. I really like the overdriven sound with single coils. Here are some foto's of my build. I used an old analog amperemeter. Enjoy!

(http://i1344.photobucket.com/albums/p650/AJDbass/Music%20-%20Electronics/100_1826.jpg~original) (http://s1344.photobucket.com/user/AJDbass/media/Music%20-%20Electronics/100_1826.jpg.html)
(http://i1344.photobucket.com/albums/p650/AJDbass/Music%20-%20Electronics/100_1887.jpg~original) (http://s1344.photobucket.com/user/AJDbass/media/Music%20-%20Electronics/100_1887.jpg.html)
(http://i1344.photobucket.com/albums/p650/AJDbass/Music%20-%20Electronics/100_1879.jpg~original) (http://s1344.photobucket.com/user/AJDbass/media/Music%20-%20Electronics/100_1879.jpg.html)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Magnus on April 23, 2014, 12:49:06 PM
Hello,
it took some time but now it is finished,
my "Murder One" in an Type-B-Enclosure.

Data:
-------
Enclosure: Hammond 1590-B
Output-Transformer: Fender Reverb-OT
Voltage-Converter: MAX1044
Tubes: NOS VALVO 5672 (Pentode) / NOS THOMSON 6111 (Triode)
PCB: etched pertinax
Resistors: Vishay Dale CMF55 (0,1% tolerance ),
standard metal-film-resistors (1% tolerance)
Capacitors: Selected NOS Tropical Fish, Panasonic FC-Electrolytics
Diodes: 1N4148, 1 x 1N4007
Power: ~ 1 Watts (?)

I used this layout: "Murder One" - V7 (http://dl.dropbox.com/u/967492/Version%207/M1V7%20Stock.gif)

...this is how it started (19 holes ;)):
(http://forum.musikding.de/cpg/albums/userpics/17258/Geh%C3%A4use%2C_gebohrt.jpg)

...the pcb before installing:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Platine%7E7.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Platine%7E7.jpg)

...guts:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Elektronik%7E10.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Elektronik%7E10.jpg)

...Tube-sockets (Inline-sockets), glued to the pcb with epoxy:
(http://forum.musikding.de/cpg/albums/userpics/17258/Inline-Sockel.jpg)

...the Tubes, ready for installing with their sockets:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_R%C3%B6hren.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/R%C3%B6hren.jpg)

...Murder One, Size-comparison:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Murder_One%2C_Gr%C3%B6ssenvergleich.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Murder_One%2C_Gr%C3%B6ssenvergleich.jpg)

...Murder One, Front-view:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Murder_One%2C_Vorderansicht.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Murder_One%2C_Vorderansicht.jpg)

...Murder One, left:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Murder_One%2C_schr%C3%A4g_links.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Murder_One%2C_schr%C3%A4g_links.jpg)

...Murder One, right:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Murder_One%2C_schr%C3%A4g_rechts.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Murder_One%2C_schr%C3%A4g_rechts.jpg)

...Murder One, activated:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Murder_One%2C_aktiv.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Murder_One%2C_aktiv.jpg)

...6111-tube-detail-picture:
(http://forum.musikding.de/cpg/albums/userpics/17258/normal_6111%2C_aktiv.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/6111%2C_aktiv.jpg)

Sounds really nice :)

At full power you can hear it in the next room
and its possible to play clean (quiter of course but still ok)...

I made the wood-plate from an old piece of wood,
hammered letters into it, sanded it and applied some thick coats of clear-coat...

Tips for other builders:

1) Take a look at the datasheet of your 6111-tube to make shure how to wire it up correctly,
I did it wrong the first time, because I installed the pcb with its solderside towards the inner enclosure  ;)

2) The 18 Ohm-resistor caused some really huge heat (flowing into the parts beneath),
I installed a cement-resistor outside of the enclosure - problem solved  ;) (Thank you for this tip, bluebunny!)

Thank you for this great circuit, Rick  :)  :)  :)


Greetings from Germany
Magnus
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: mth5044 on April 23, 2014, 12:58:25 PM
That is beautiful! Great job!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Magnus on April 25, 2014, 04:32:14 PM
Thank you  :)


Greetings
Magnus
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Perrow on April 25, 2014, 06:11:16 PM
...this is how it started (19 holes ;)):
(http://forum.musikding.de/cpg/albums/userpics/17258/Geh%C3%A4use%2C_gebohrt.jpg)

Nice work there (and not just the drilling). That's how my 1590A looked like before installing my Superfly, didn't have room for tube guards so only 15 holes, but then again, on a A size enclosure.

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Brymus on April 25, 2014, 09:37:15 PM
Beautiful Magnus !!!! :icon_mrgreen:
I love it looks like Rick built it himself. :icon_cool:
Soundclip please?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Magnus on April 26, 2014, 08:44:20 AM
Hello,

@Perrow:
Thank you  :)
I know your project - great looking build and really small  ;)

@Brymus:
Thank you for your kind words  :)
I can not record sound clips because I don't have an interface and a microphone, sorry...


Greetings
Magnus
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kalegood on May 24, 2014, 11:44:38 PM
Wondering if I could get some trouble-shooting help here. This is my first electronics project, so, ya know. Learnin' a bit.

I built my Murder One and had a high-pitched hum that I thought was a grounding issue on the pot. Everything else was working well, though. I put it in the enclosure and now it has stopped working. No amplification at all (well, some, but no output).

I've borrow my friend's oscilloscope; the preamp stage is working fine from what I can tell (the signal is amplified 2x). On the preamp, here is what my readings are (same results with 2 different tubes):

Pin 1: no signal, no voltage
Pin 2: 70 volts, signal about 1/2 of the input (from the 1/4 inch jack).
Pin 3: a bit more than 1 volt
Pin 4: same as the output from the preamp
Pin 5: the ground is good.

It may be good to note that I crossed B+ and the other power line, frying my ICL7660. That has been replaced, obviously.

Any help would be appreciated.

Thanks,
kale
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kalegood on May 25, 2014, 10:37:56 AM
Ok, so after reading through this entire thread, I thought some other info might be useful.

Grounding: I have the input, output, and the black wire of OT grounded to the case (on one of the OT bolts).

The blue wire of the OT is getting 63 volts. (63 volts for pin 2 as well, rather than the above stated 70).

Not sure why I'm not getting any voltage at pin 1 (or out of the red OT wire).
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on May 25, 2014, 11:17:13 AM
If the "top" of your OT primary has volts, but the "bottom" doesn't, then perhaps the OT is shot?  It's a piece of wire after all, so there should be continuity from one end of the primary to the other (you could take it out and check).  BTW, I had my green wire go to ground on the secondary side.

BTW, welcome along, and good on you for reading all 26 pages!  :)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kalegood on May 25, 2014, 01:27:53 PM
Ok, looks like I fried the OT. This seems a bit odd to me because the amp was working intermittently for a while (if I wiggled the board around, I could occasionally get crackling). I thought that maybe the wires in the OT had gotten damaged, but wiggling around the wires while checking resistance gave the same results.

Any idea how I could have done this? I'm at about 63 volts on B+. The R3 resistor maxes out my analogue multimeter. Could the OT have fried if I had accidentally crossed the secondary wires for too long?

Why is it that my DIY projects are never cheaper than buying a pre-made item. Ah, well. Its a learning experience.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on May 26, 2014, 03:48:08 PM
I only had sixty-something volts B+.  Too much/too many diode drops?  Perhaps Schottkys might have been better...   :-\   But anyway, works at the slightly "lower" voltage.  So far as the OT goes, an open secondary traditionally causes trouble.  More learned fellows will be along presently to explain why.  :)  Not sure if a short is dangerous too...  Did you disconnect the OT to check the primary, btw?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: kalegood on May 26, 2014, 10:09:37 PM
yeah, the OT was out of the circuit.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: thomasha on June 30, 2014, 02:08:25 PM
Hi,
after using the output transformer in a 12au7 SE amp my murder one was resting in a box, but after some reading I tried to use a 220 to 5.5 V transformer as the output transformer and it worked!

The sound is still an issue... with my transformer the tone lost a lot of bass and there is a strange distortion when the volume is maxed.

Since this amp has such a low wattage, and this low voltage transformers are easier to find than the fender reverb transformer, at least in my country, would it be possible to adapt this transformer or design a smaller one?

I was thinking of starting with a lamination that has the air gap or cut an air gap in the original lamination.

Another approach would be change the lamination material, to obtain a better bass response from a smaller transformer, but this part is a little more difficult to understand and maybe someone could help explaining?

I read some audio transformer design articles, but the winding plays the important role, and the core size are never smaller than a core size required for a 5 W amp.

I know the winding plays an important role, but winding an output transformer without the required equipment is very exhausting. Change or adapt the lamination sounds easier to me.

The main goal is something as a low size and easy to find SE transformer. Or at least test some changes in the OT.

Cheers



Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: mcandmar on October 01, 2015, 07:41:49 PM
Just registered to say thanks all for sharing the schematics and info, i couldn't resist building something so cute :)

(http://www.cr-x.org/temp/img_0525.jpg)
(http://www.cr-x.org/temp/img_0527.jpg)
(http://www.cr-x.org/temp/img_0538.jpg)

At the moment i am using a basic speaker from a Fender Frontman 15g and it sounds surprisingly good.  I'm also impressed with the range of sounds it has from clean to distorted. Only change i made from the schematic was the 6111 heater resistor, it ran way too hot for comfort so i replaced it with an LM317 mounted under the circuit board using the chassis as a heatsink.

Cheers all!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Fast Pistoleros on February 26, 2016, 01:56:50 PM


Curious what the B+ connection is ? does that go to one ond of teh diodes and then the other two +12 go to the power supply input jack?  what is the data sheet specs on the bom specificaly the transformer? if i google search fender reverb transformer will that be the one to buy?  thanks

I think i got it .. the b+ is the -60-70 coming off the voltage inverter and the other two 12+ leads go to the +12 rail on the input supply , all get a common ground...is this where i can put my 1/0 switch with an LED indicator to toggle the circuit open and closed?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: substatica on May 04, 2016, 10:18:52 PM
Test fitting my Murder One (temporary plastic protection bars). I saw somewhere someone used some rubber grommets for the tube holes so I did the same -- does that seem like a heat/vent problem to anyone? How hot do these little  tubes get? Currently they're snug against the grommets. Cheers.

(http://i.imgur.com/8XN663C.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: substatica on May 05, 2016, 10:53:20 AM
Also, where would be the best place for the power switch be? I would think switch the 12 volts coming from the adapter and run the power LED off that with its resistor to ground. Is that how others are wiring it?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Jdansti on May 05, 2016, 09:32:09 PM
Also, where would be the best place for the power switch be? I would think switch the 12 volts coming from the adapter and run the power LED off that with its resistor to ground. Is that how others are wiring it?

That's how I did mine. The power switch is between the DC jack and the circuit. The LED and resistor are wired in parallel with the amp.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: substatica on May 06, 2016, 09:52:19 PM
Have it all together but not getting any audio output :( I have to admit I forgot I put on a negative center power jack and had the polarity reversed when I first turned it on, would that have borked anything?

I measured 65 VDC coming out of the power section -- where should I look next?


(http://i.imgur.com/KQuN3gn.jpg)

(http://i.imgur.com/N4eWX3Q.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: Jdansti on May 06, 2016, 10:28:20 PM
Looks like you didn't damage the 1044. The reverse polarity shouldn't hurt the tube heaters and I don't think it would have damaged the tubes otherwise, but I don't know what output if any the voltage multiplier would have created when the polarity was reversed.

Just for thoroughness, if it were me, I'd check to make sure the guitar and cable work with another amp. Make sure your guitar's volume is turned up. Seriously, stupid little things like that can cost you a lot of troubleshooting time if you don't check. Also make sure your speaker and speaker cable work by testing with another signal.

If all of the above are fine, then use an audio probe and follow the signal starting at the input and work through the tubes. Use the schematic to see which tube pins to check for signal. I don't think you want to use the audio probe on the transformer output. You have a speaker to check that. Everything else in the signal path on the other side of the transformer is ok to check.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: substatica on May 06, 2016, 11:01:00 PM
Looks like you didn't damage the 1044. The reverse polarity shouldn't hurt the tube heaters and I don't think it would have damaged the tubes otherwise, but I don't know what output if any the voltage multiplier would have created when the polarity was reversed.

Just for thoroughness, if it were me, I'd check to make sure the guitar and cable work with another amp. Make sure your guitar's volume is turned up. Seriously, stupid little things like that can cost you a lot of troubleshooting time if you don't check. Also make sure your speaker and speaker cable work by testing with another signal.

If all of the above are fine, then use an audio probe and follow the signal starting at the input and work through the tubes. Use the schematic to see which tube pins to check for signal. I don't think you want to use the audio probe on the transformer output. You have a speaker to check that. Everything else in the signal path on the other side of the transformer is ok to check.

I'll start with a signal probe. I see a dull glow form the Pentode, but no sound whatsoever, no signal, no noise.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: substatica on May 07, 2016, 10:55:31 AM
If all of the above are fine, then use an audio probe and follow the signal starting at the input and work through the tubes. Use the schematic to see which tube pins to check for signal. I don't think you want to use the audio probe on the transformer output. You have a speaker to check that. Everything else in the signal path on the other side of the transformer is ok to check.

This is only my second tube amp, first was from a kit, so I'm not sure I'm following the signal through the tubes correctly. I'm not getting any glow off of the 6111 whereas the 5672's got a nice orange on the heater. The audio signal has tons of buzz and drops to almost inaudible once through the the 6111.

If I'm reading the spec correct the 6111 should have 6.3v at pin 3 and 6 for the heater yeah? I'm reading 12V at pin 3 and 0V at pin 6, could the heater filament be broken?

What other ways can I test the tube?

http://frank.pocnet.net/sheets/127/6/6111.pdf

http://frank.pocnet.net/sheets/127/5/5672.pdf

(http://i.imgur.com/CmBu98s.jpg)

(http://i.imgur.com/y5pGWNu.jpg)

(http://i.imgur.com/3hobKWa.jpg)

(http://i.imgur.com/0R4dFNP.jpg)
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: substatica on May 07, 2016, 03:09:22 PM
It's alive! Turns out I had the 6111 in reversed, I think that fried both tubes and eventually the IC, once I swapped all those out I've got sound! Quiet sound, but I think that's just the amp output power ;) Now to take care of the motorboating when dimed!
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on May 08, 2016, 07:31:04 AM
There are mods in the thread to stop the motorboating.  (You'll have to read through to find them.)  Worked like a dream for me.
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: substatica on May 08, 2016, 09:38:15 AM
There are mods in the thread to stop the motorboating.  (You'll have to read through to find them.)  Worked like a dream for me.

Yup, already swapped R1, R2 for 100K and R12 for 470K. Motorboating gone -- does that mod drop the max output?
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: bluebunny on May 08, 2016, 11:21:53 AM
Not that I noticed.  I thought it was still pretty loud.  So did a mate of mine when we used it for some recording.  YMMV, of course...
Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: substatica on May 10, 2016, 10:33:50 AM
Any idea why @frequencycentral used washers under the OT and roll bars? Just to give the OT a level base?
Title: Re: All New "Murder One" redesign and layout!! Modder's Delight!
Post by: Mgt280y on May 07, 2017, 05:22:44 PM
The original Murder One was 'baby's first amp'. I've learned a lot since then and the design has gradually changed over time. This one is a major upgrade, and now it's looking much more like a serious amp. What's changed:

  • Input section is different (R6/R11), the original was more like what you'd see in a pedal.
  • Preamp stages rebiased with 47k anode resistors (R1 and R2) and the addition of cathode resistors and bypass caps (R9/C19 and R10/C15)
  • Grid stoppers added between stages (R12 and R13), R12 is essential, R13 is optional and may be jumpered instead
  • New schematic with component values matching the...
  • ...new layout
  • Tweakable values are asterisked *
  • Fatter traces and pads on the layout - for a fatter sound!


The result of these additions is that the anodes are running at much higher voltage, the clean sound is much better than it was - very usable now, and the cranked sound is fatter and has more body.

As this is the Modder's Delight version, any tweaks to suggested values should be considered in conjuction with this article: http://www.diystompboxes.com/pedals/tubedummy.html

I have verified the new layout onto perf, it works really well. If anyone feels like etching me a board or two I'd be proud to accept them!

(http://i210.photobucket.com/albums/bb292/frequencycentral/MurderOneV6.jpg)

(http://i210.photobucket.com/albums/bb292/frequencycentral/ModdersDelightPCB.gif)

(http://i210.photobucket.com/albums/bb292/frequencycentral/ModdersDelightPnP.gif)

Good evening all, im in the process of building this verision, done a slightly different layout for pcb

Couple of things is there a verson 7 as the thread references but can find a schematic or layout

I noticed duribng the evolution of the murder 1 the transformer has changed what does this affect and have people used other than 1750a on this verson

Main question is if i wanted to add a headphone out 3.5mm jack how is it added to the schematic and in terms of loading does the 8 ohm speaker always need to be connected/dummy load.

Thinking maybe speaker and head phone sockets on a spdt so i could switch from cab output to headphones

Any help as always much appreciated

Title: Re: New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage
Post by: thomasha on May 07, 2017, 06:03:30 PM
Version 7 of the modder's delight version.
Without the bias switch, but with a preamp out switch.
Look for the vibratone subminiature tube amp thread for more information. I think an 8 ohm load was added in case there was no speaker conected (preamp signal only).

The headphones output requires another Jack, where both speakers are in parallel.
You can't use the same output Jack because amp cables normally are mono, meaning you would ground one side.