I want to build a preamp tube that can go into any poweramp but in pedal format. Maybe 1590BB enclosure. Something like kingsley preamp.
My plans are
1. Build a clean preamp using one 12ax7 tube
2. Build a tone stack of Dumble or Vox
3. Use 2 Transformer 12v by 220/240v
4. Rectifier and regulator maybe LM317 to acheive 6.3v for the heater.
Any ideas that i need to? I'll post my schematic soon. Or find schematic that i can use. Thank you so much. Hope someone can help me.
I would recommend the Alembic F2-B here http://moosapotamus.net/ideas/alembic-f-2b-preamp/ This will do all you want. :)
Thank you for your response. I will study this one and i hope i can build this project soon.
You may want to check out https://el34world.com/projects/tube_box_3.htm
There's a cat around here that has boards for this very thing. I have two that I haven't built yet, but it's a nice project. http://frogpedals.com/index.php/product-category/pcb-products/ (http://frogpedals.com/index.php/product-category/pcb-products/)
Also, look at the Omnibox: https://www.diystompboxes.com/smfforum/index.php?topic=120628.0
I would like to buy one of the frog pedal pcb's but shipping and tax makes them pretty expensive.
I would do the F2-B also. Any tone stack variant can go between the triodes, although some were designed to be driven by a low impedance cathode follower stage, it doesn't change things much with the common cathode drive.
Not that making a regulated DC heater supply is particularly difficult or expensive but...
If your transformers are near enough 12v rms, you can get surprisingly good results by running the heaters right off the 12vAC (pin 9 ground, supply across 4 & 5). It's only 150mA current and thinner wire like 7/0.2 can be tightly twisted to deliver low-hum heater power. Grounding pin 9 means you don't need a humdinger, although if at least one transformer has a centre tap secondary, you can ground that instead and leave the tube pin 9 disconnected.
...but if you want DC for auxiliary circuits and will be rectifying the 12v anyway, it may as well have regulated DC heater power.
I thank all of you for your responses. I will try to visit the links you posted. And also try to post a schematic and ask for your opinions and suggestion about my project.
Quote from: anotherjim on August 23, 2018, 02:32:05 PM
Not that making a regulated DC heater supply is particularly difficult or expensive but...
If your transformers are near enough 12v rms, you can get surprisingly good results by running the heaters right off the 12vAC (pin 9 ground, supply across 4 & 5). It's only 150mA current and thinner wire like 7/0.2 can be tightly twisted to deliver low-hum heater power. Grounding pin 9 means you don't need a humdinger, although if at least one transformer has a centre tap secondary, you can ground that instead and leave the tube pin 9 disconnected.
Don't connect it like this for 12 volt operation. If you run the heater from 12 volts (AC or DC), leave pin 9 open and put the voltage across pins 4 and 5. Pin 9 is the centre tap of the heater. You only connect pin 9 if you are running from 6 volts (AC or DC).
Here's my initial layout. A rough layout only. Based on two rock clean stage. Any thoughts? Thank you.
(https://s8.postimg.cc/aw9aq4yqp/project.png) (https://postimg.cc/image/aw9aq4yqp/)
(https://s8.postimg.cc/lkd1ow8ox/20180825_091029.jpg) (https://postimg.cc/image/lkd1ow8ox/)
Just a heads up that if you're digging into the Dumble inspired stuff, like the Two Rock, you're DEFINITELY gonna wanna check out what's going on over at the AmpGarage forum.
Thanks for the information. I will check the site and do the research. That's very helpful..
(https://s33.postimg.cc/5z3mfo26j/F1739872-02.jpg) (https://postimg.cc/image/5z3mfo26j/)
will this transformer work?
Hi man, :)
I would not use transformers at all. They are big, heavy and overall its dangerous do work with AC .
I would recommend an SMPS such as this one:
(http://blog.soundcubed.com/images/555%20smps%20schematic%20soundcubed.JPG)
The a Tube based guitar pedal would fit here in 1590C easily like such:
(http://blog.soundcubed.com/images/Trem-O-Drive.jpeg)
Dangerous to do work with AC? And the dc going to the plate is of no concern? But really higher voltages are not a think to be afraid of, something to be careful of, yes, afraid no.
Now if I were to do a preamp circuit with a tube (and I am) I would use a switching wallwart power supply putting out 12V. Run the heater of it, send the 12V into one of these.
https://www.ebay.com/itm/DC-DC-8-32V-To-45-390V-High-Voltage-Boost-Converter-ZVS-Step-up-Booster-Module/232748063564?epid=1476662431&hash=item3630dd9b4c:g:HpcAAOSwvcVa4plQ
(https://ae01.alicdn.com/kf/HTB1LCBeLXXXXXawXpXXq6xXFXXXm/DC-DC-Boost-Converter-8-32V-to-45-390V-High-Voltage-ZVS-Capacitor-Charging-Board-220V.jpg)
Adjust to whatever voltage you want, no cheesy back to back transformers. It puts out much more power than needed, wish they had a low current smaller model. I took a hack saw and cut off the heatsink flush with the circuit board.
> Dangerous to do work with AC? And the dc going to the plate is of no concern?
Connection to a wall-plug can burn-down the house, or at least scorch the workbench-- current available is very large.
Plate supply is still lethal but less dangerous.
I really like the idea of using an smps. I'll order this smps and try to build preamp as soon as my components are complete. I'll update this post for my progress. :) thank you so much. Please keep on helping me.
Not much love for transformers then...
I don't think it's common practice to use a pair of back to back transformers inside a pedal. Rather, you use an external 12Vac wall wart and make the HT with a back-driven transformer in the pedal. In this case, a connector that cannot make any contact with the standard 2.1mm connector in the ordinary 9Vdc pedals should be found for the 12Vac connection, since many 9v pedals will not like an AC supply up them.
As to the choice of back-drive transformer, a 3VA might be better, although the suggested 1.6VA is just about going to do it, there is very little overload margin. These little encapsulated transformers are pretty feeble creatures, and faced with overload will just be loaded down and do nothing, while something more substantial could start smoking.
Although a potential problem with an AC supply is that you might get some 50/60Hz hum, any smps based supply or boost converter has a switching frequency which might be low enough to be audible, or if ultrasonic, mix with some other ultrasonic source (maybe a BBD delay clock or another smps) and produce audible interference that could be more troublesome than a little hum.
QuoteAlthough a potential problem with an AC supply is that you might get some 50/60Hz hum, any smps based supply or boost converter has a switching frequency which might be low enough to be audible, or if ultrasonic, mix with some other ultrasonic source (maybe a BBD delay clock or another smps) and produce audible interference that could be more troublesome than a little hum.
Well this SMPS is almost silent, because it operates at ~30kHz and with the right capacitor material it almost does not have any harmonics ( which we can "see" on an oscilloscope but not hear). And if you really need to quiet it down, then I recommend using a 100R to 470R resistor between the circuit and the SMPS.
I agree with the anotherjim, 1.6VA probably won't cut it. 12V x 0.15A (amount of current 12ax7 draws) = 1.8VA.
Actually if you are going to convert the filament voltage to DC, you'll need one rated more than that even - around 3VA for a bridge rectifier scheme.
The power rectification guide on Hammond's website explains it pretty well:
http://www.hammondmfg.com/pdf/5c007.pdf
Quote from: Jeema on September 02, 2018, 03:45:28 PM
12V x 0.15A (amount of current 12ax7 draws)
Considerably more at startup.
I was referring to the 1.6VA used backwards as the "step up" transformer and it definitely isn't supplying the filament. To put the incoming AC supply step-down transformer inside the pedal means having to deal with potentially dangerous power - we don't encourage that for amateur/DIY work, although there are and have been plenty of commercial guitar pedal products with the AC wall supply on board.
If you use a commercial 12vAC power adapter, you entirely bypass the problems and dangers of producing that part yourself.
My first plan is to use the backward transformer setup having the main power supply outside like how tube pedals work. (eg. Kingsley) but what is more advisable to use in terms of space saving and noise or hum or interference? Will backward transformer will produce a better result or smps?
I would go with the backwards transformer as the lower noise solution. But if the plate voltages you are running are not that high, you can use a Cockroft-Walton voltage multiplier directly off the filament windings. This would allow you to not bother with the second transformer in the unit.
Quote from: PRR on September 01, 2018, 10:10:26 PM
> Dangerous to do work with AC? And the dc going to the plate is of no concern?
Connection to a wall-plug can burn-down the house, or at least scorch the workbench-- current available is very large.
Plate supply is still lethal but less dangerous.
Not too sure about this one. At least if we are talking about North American voltages. A 120V service is going to give 170V peak potential. Whereas a tube amp (I was talking more tube amps than what is needed for this circuit) can supply 50-100mA easy. That is in the kill range given that voltages are 250-450V. And with the AC line voltage the current gets interrupted 120 times a second. DC is continuous and there is no current interruption that gives you a chance to break the circuit. I have been zapped by 120V many times in life with line voltage. You work with it enough stuff happens. But other than feeling crappy afterward I have walked away.
Thankfully I have not been zapped much with higher voltages (only twice, big photocopier transformer putting out couple of thousand volts and resetting breakers in an electrical storm), 208 V and above are the real dangerous ones in terms of people and not being able to get up and walk away from. Not that I advise people being cavalier with any voltage above 50V but if I am going to be poked I would prefer it be 120 V than any higher voltages.
I have used switching 12 Vdc power supplies, it is rare for transformer filled adapters to be made today, for the filament and switched up the high voltage with the module shown earlier. No audible noise given a reasonable about of gain. I have been won over by the little switching power supplies and no longer use transformers in my amps and pedals. It is easier finding a switched power supply now days than an adapter that puts out 12V AC. You can go in some 12V dc adapters and remove the rectification but most adapters are sealed in a way where you destroy the seal going in.
Quote from: anotherjim on September 02, 2018, 05:07:17 PM
I was referring to the 1.6VA used backwards as the "step up" transformer and it definitely isn't supplying the filament. To put the incoming AC supply step-down transformer inside the pedal means having to deal with potentially dangerous power - we don't encourage that for amateur/DIY work, although there are and have been plenty of commercial guitar pedal products with the AC wall supply on board.
If you use a commercial 12vAC power adapter, you entirely bypass the problems and dangers of producing that part yourself.
Agreed - dealing with wall voltage directly requires very careful attention to safety due to the high current potential. The safest way is to use a 12VDC or 12VAC adapter and step up internally.
Let's also not forget that even with isolated HV DC you can still potentially electrocute yourself hand-to-hand if you don't obey the "one hand" rule when messing with energized circuits and capacitors. In fact anyone messing with HV anything should make sure they're aware of ALL of the safety considerations first.
I am aware how we need to be careful enough when we are working on HV devices. I think i will use a backward transformer since i do not need big transformer for 150ma of current to make the tube pedal work. But the only downside of it is i need to use an external AC 12v powersupply rather than a typical dc 12v power supply.
I'm finishing testing of 5670 based bass preamp, it sound nice, but I didn't make it in pedal format. Sound's good, but maybe too sharp compared to 12AX7 based Alembic F2b.
My design would be based in the following reasoning after seeing all the posts in this thread:
- Being aware of the extreme care held when dealing with mains AC voltage and high DC voltages, I would choose to only deal with one of them DC.
- I would run the SMPS and the tube heaters from a standard 9V DC PSU because makes the pedal board simpler and if you forget the AC transformer, there is no problem. Generally we can assume that the 12AX7 operates between 5,5V to 13V AC or DC, 150mA to 300mA, this means that they work at 1,9W. At 9V they consume 200mA.
- With the HV SMPS I posted the output, besides being very very quiet, is adjustable.
The block diagram would be like this:
(https://blog.soundcubed.com/images/Tube_Layout.png)
Just quick note - the best way to provide correct voltage for heaters is to use a resistor. If you have 9V DC supply and 6.3V heaters requiring 300mA, then you must put 9.1 ohm resistor in series with heaters.
Indeed sir, a 10R /5Watt resistor, thanks, forgot about the series parallel wiring of the 12AX7 filament :). Just a note, the 9V in heater in series works well the tube just glows slightly less and is a bit grungier. :icon_biggrin:
i think i will try a fender preamp first. here is my current ugly layout without power supply.
how to smps supply with this layout?
(https://s15.postimg.cc/ldoa10287/tube_pre_layout.png) (https://postimg.cc/image/ldoa10287/)
Quote from: MJ_Sound_Cubed on September 03, 2018, 04:57:32 PM
Indeed sir, a 10R /5Watt resistor, thanks, forgot about the series parallel wiring of the 12AX7 filament :). Just a note, the 9V in heater in series works well the tube just glows slightly less and is a bit grungier. :icon_biggrin:
2W rated resistor is quite sufficient in this case, or you can use two 18 ohm / 1W resistors in parallel.
will this smps work?
(https://s15.postimg.cc/6o81akx5j/Screenshot_1.png) (https://postimg.cc/image/6o81akx5j/)
Breadboard and try :)
(http://www.circuitfx.com/wp-content/uploads/2018/05/SOLDANO_GUITAR_TUBE_PREAMP_2-830x551.jpg)
I do use back to back power transformer 12VAC 300mA. it work great without problem. I did try SMPS it have noise issue.
Quote from: pravudh on September 04, 2018, 05:47:13 AM
(http://www.circuitfx.com/wp-content/uploads/2018/05/SOLDANO_GUITAR_TUBE_PREAMP_2-830x551.jpg)
I do use back to back power transformer 12VAC 300mA. it work great without problem. I did try SMPS it have noise issue.
Amazing work! Do you have a demo of this sir?
Exactly as expected, the SMPS does generate more noise than a reversed transformer when implemented as a boost converter. There are other topologies for an SMPS which include resonant converters and current-mode converters that are much quieter. Also, with the current drain of a couple of 12AX7's, you can make a boost converter work if you push the frequency up into nearly the megahertz region, but an NE555 will definitely not do that. I like the idea of a voltage multiplier rectifier array (Cockroft - Walton) because it saves the space, weight and expense of a transformer but the transformer is simpler, uses fewer parts and gets better regulation.
One idea that you might look into: biasing the heaters to a positive voltage. Small parts of the heater may protrude above and below the mica insulator in the tubes that hold the electrodes in position. The heater is capable of emitting a small amount of current but if it is biased positive, the protruding part of the grid will completely block the current flow. This has been shown to reduce hum by a slight amount. Some tubes are more of a problem than others from this point of view.
Although it is not a wall wart as such, there are doorbell transformers that plug into a standard power socket and provide a nominal 10 VAC or 14 VAC output. The advantage of a doorbell transformer is that there is so much leakage inductance designed into it that shorting the output will not cause damaging or dangerous currents to flow.
I have a whole "line" of SMPS-based tube pedals and have never had issues with noise. I also use a 6V regulator with a schottkey between middle pin and ground for 6.3V as I don't want to cram a 5W resistor into my pedals, I can get regulators much smaller. I use Russian submini tubes for everything because I like to keep everything in 1590B's, so space is a bit of a premium.
Also cheers to cab42 on mentioning the Omnibox :) It's a little more than a preamp, but all it would take to turn it into a straight F-2B preamp is a jumper. That being said it's an SMD build, so not everyone's favorite thing :P
First, here is a verified 555 SMPS layout:
(http://blog.soundcubed.com/images/555SMPS.gif)
Here is a video of guitar amplifier with a 555 SMPS played clean with a Stratocaster, and it does not have any noise issues.
(https://artis3dots.files.wordpress.com/2016/07/pic-5.jpg?w=300)
Having tried both, back to back trafos ( even some I wound) and the SMPS, I have learned that the SMPS is as quiet as the power supply it is plugged in, the quality and material of the output capacitor and the layout.
QuoteI also use a 6V regulator with a schottkey between middle pin and ground for 6.3V as I don't want to cram a 5W resistor into my pedals
Now my dear friend vigilante397, Can you tell me more about that heater PSU with diodes and other parts? :D
Quote from: MJ_Sound_Cubed on September 04, 2018, 04:21:16 PM
Now my dear friend vigilante397, Can you tell me more about that heater PSU with diodes and other parts? :D
Absolutely. I'm on my phone so I can't draw anything up for you, but this is how I do it:
I use an L7806 regulator, or a 78M06 on SMD builds. The middle pin is the GND reference, so if you tie it to common ground you will get a 6V output. If you get a schottkey diode with a 300mV forward voltage between that pin and ground then your output will go 300mV higher, meaning a 6.3V output.
I have also seen this done with an L7805 and two 1N4001 diodes. They have a forward voltage of 700mV, so a pair of them in series between the GND pin and ground will bring you 1.4V higher for a 6.4V output. A lot of people like this better because you're more likely to already have some 5V regulators lying around.
As with any voltage regulator it's a good idea to put filter caps on the input and output. I usually do minimum 220nF on input and minimum 100nF on output. So aside from saving space over a resistor this also ensures you will get nice quiet DC voltage for your heaters ;D
EDIT: Just remembered I had this pic on the OmniBox thread so I can throw it in here so you see what I did. And you can ignore the extra filter stages on the 555 SMPS, it was an experiment that didn't add any benefit.
(https://i.imgur.com/YL0wkmx.jpg)
(http://i1249.photobucket.com/albums/hh520/johngovan1234/Screenshot_1_zpsvdsjms8k.png) (http://s1249.photobucket.com/user/johngovan1234/media/Screenshot_1_zpsvdsjms8k.png.html)
here is my pcb layout. Copied from Waltk with some traces modifications. not yet verified.
Nice layout, but better check inductor size. This inductor must be 3A rated, best with toroidal core.
Quote from: rankot on September 05, 2018, 10:08:15 AM
This inductor must be 3A rated
I agree the inductor footprint should probably be bigger, but 3A seems excessive. The ones I use are rated for 1.9A and they do fine.
Definitely agree with the ferrite core though. ;D It's not a bad idea to find an inductor first then make your footprint, rather than trying to force whatever you find into the footprint you made.
(https://circuitfx.files.wordpress.com/2011/10/gto_01.jpg?w=640&h=1&crop=1)
My first tube pedal with SMPS it make strange resonance noise issue when I play with Flanger pedal.
Quote from: johngovan1234 on September 04, 2018, 07:43:43 AM
Quote from: pravudh on September 04, 2018, 05:47:13 AM
(http://www.circuitfx.com/wp-content/uploads/2018/05/SOLDANO_GUITAR_TUBE_PREAMP_2-830x551.jpg)
I do use back to back power transformer 12VAC 300mA. it work great without problem. I did try SMPS it have noise issue.
Amazing work! Do you have a demo of this sir?
Quote from: johngovan1234 on September 05, 2018, 09:28:03 AM
(http://i1249.photobucket.com/albums/hh520/johngovan1234/Screenshot_1_zpsvdsjms8k.png) (http://s1249.photobucket.com/user/johngovan1234/media/Screenshot_1_zpsvdsjms8k.png.html)
here is my pcb layout. Copied from Waltk with some traces modifications. not yet verified.
Great layout, for less thank 15mA like a single tube preamp, even a 100uH 1A ferrite core inductor is enough. Please make sure the layout has space for a radiator in the MOSFET.
Quote
My first tube pedal with SMPS it make strange resonance noise issue when I play with Flanger pedal.
This happened when the phaser was before of after the SMPS effect?
Quote from: vigilante397 on September 04, 2018, 08:53:21 PM
Quote from: MJ_Sound_Cubed on September 04, 2018, 04:21:16 PM
Now my dear friend vigilante397, Can you tell me more about that heater PSU with diodes and other parts? :D
Absolutely. I'm on my phone so I can't draw anything up for you, but this is how I do it:
I use an L7806 regulator, or a 78M06 on SMD builds. The middle pin is the GND reference, so if you tie it to common ground you will get a 6V output. If you get a schottkey diode with a 300mV forward voltage between that pin and ground then your output will go 300mV higher, meaning a 6.3V output.
I have also seen this done with an L7805 and two 1N4001 diodes. They have a forward voltage of 700mV, so a pair of them in series between the GND pin and ground will bring you 1.4V higher for a 6.4V output. A lot of people like this better because you're more likely to already have some 5V regulators lying around.
As with any voltage regulator it's a good idea to put filter caps on the input and output. I usually do minimum 220nF on input and minimum 100nF on output. So aside from saving space over a resistor this also ensures you will get nice quiet DC voltage for your heaters ;D
EDIT: Just remembered I had this pic on the OmniBox thread so I can throw it in here so you see what I did. And you can ignore the extra filter stages on the 555 SMPS, it was an experiment that didn't add any benefit.
(https://i.imgur.com/YL0wkmx.jpg)
This was a fantastic help :) Do you use SMD parts?
Quote from: MJ_Sound_Cubed on September 05, 2018, 01:51:14 PM
This was a fantastic help :) Do you use SMD parts?
Mostly, yup ;D 1590B is my absolute favorite enclosure size, but I LOVE tube pedals, so I've been using Russian submini tubes and SMD to fit any tube pedal I want into a 1590B. This is my latest, a tube-driven BTDR-2 reverb. An excellent example of making a footprint before I had the component :P That's why the regulator footprints are so much bigger than the actual component. Whoops ::)
(https://i.imgur.com/bSrobvU.jpg)
(https://i.imgur.com/wLsY9Ac.jpg)
Quote from: vigilante397 on September 05, 2018, 03:28:04 PM
Quote from: MJ_Sound_Cubed on September 05, 2018, 01:51:14 PM
This was a fantastic help :) Do you use SMD parts?
Mostly, yup ;D 1590B is my absolute favorite enclosure size, but I LOVE tube pedals, so I've been using Russian submini tubes and SMD to fit any tube pedal I want into a 1590B. This is my latest, a tube-driven BTDR-2 reverb. An excellent example of making a footprint before I had the component :P That's why the regulator footprints are so much bigger than the actual component. Whoops ::)
(https://i.imgur.com/bSrobvU.jpg)
(https://i.imgur.com/wLsY9Ac.jpg)
That a really good looking idea, how does it sound like? :) Do you have a demo.
I have some of those 6n17b and 6n16b submini tubes. But never thought about something as cool as hybrid pedal sized, tube powered reverb like that :)
Those boards look seriously good :) you are ordering them from where ?
I saw your page you have some really cool work going on. Why are closing down your website next week? Thats a pitty.
Final question:
Do you like tiny tube amps?
Quote from: MJ_Sound_Cubed on September 05, 2018, 03:52:46 PM
That a really good looking idea, how does it sound like? :) Do you have a demo.
I have some of those 6n17b and 6n16b submini tubes. But never thought about something as cool as hybrid pedal sized, tube powered reverb like that :)
Those boards look seriously good :) you are ordering them from where ?
I saw your page you have some really cool work going on. Why are closing down your website next week? Thats a pitty.
Final question:
Do you like tiny tube amps?
In order: Not only do I have a quick demo, there's a whole thread 8) https://www.diystompboxes.com/smfforum/index.php?topic=120732.0
The boards are from Elecrow. Now that I actually know what I'm doing in the design stage I get consistently good results from Elecrow boards.
I'm not actually closing down my page, more just focusing less on it. I mostly wanted a .com website when I was in college to impress recruiters, but now that it worked and I have a job there's less of a need :P So I'm keeping the URL but closing down the eCommerce because it costs quite a bit and in the 2 years the website has been up I have had $0 go through it. 100% of my sales have either been local word-of-mouth or people on Facebook that pay me with PayPal. So I stopped updating the official website and all of my updates and stuff has been on my Facebook page.
And lastly, I love the idea of tiny tube amps, and building one has been on my to-do list for years now, but I've never really gotten around to it :P I have all the parts I would need just sitting around my garage, I just need to clear out my backlog, which will take approximately forever. But as soon as forever is over I absolutely plan to build a tiny tube amp. Probably something high-gain, because that's the main sound I'm missing in my arsenal right now :icon_twisted:
Quote from: vigilante397 on September 05, 2018, 03:28:04 PM
Quote from: MJ_Sound_Cubed on September 05, 2018, 01:51:14 PM
This was a fantastic help :) Do you use SMD parts?
Mostly, yup ;D 1590B is my absolute favorite enclosure size, but I LOVE tube pedals, so I've been using Russian submini tubes and SMD to fit any tube pedal I want into a 1590B. This is my latest, a tube-driven BTDR-2 reverb. An excellent example of making a footprint before I had the component :P That's why the regulator footprints are so much bigger than the actual component. Whoops ::)
(https://i.imgur.com/bSrobvU.jpg)
(https://i.imgur.com/wLsY9Ac.jpg)
What a great work sir. Very professional looking circuit.
(http://i1249.photobucket.com/albums/hh520/johngovan1234/20180906_210926_zpsjej66ocy.jpg) (http://s1249.photobucket.com/user/johngovan1234/media/20180906_210926_zpsjej66ocy.jpg.html)
I found this inductor on my old router. Can i use this tho it is rated 150uH?
I'm going to go with probably. 100uH is a good number for the inductor, but not a magic number by any means. I've seen plenty of people that just used whatever inductor they had lying around and had it work just fine.
Usually 100uH do the job well :)
Simulation shows that bigger the oscillator frequency, lower inductance should be.
My next question is what are the voltage rating of coupling capacitors, tone stack capacitors and cathode capacitors? Thank you..
;D
I would recommend 30% higher than the anode and cathode voltages.
For coupling absolutely aim high. For preamps I usually shoot for 300V plate voltage and I use 400V coupling caps. For tone stack caps it depends on the setup of your tone stack. If there's another cap between the high voltage and the tone stack then you can get away with lower voltage caps in the tone stack.
(http://i1249.photobucket.com/albums/hh520/johngovan1234/Screenshot_2_zpsdhjn64ff.png) (http://s1249.photobucket.com/user/johngovan1234/media/Screenshot_2_zpsdhjn64ff.png.html)
my buying list. i already have resistors and cheap cathode capacitors at home. I think it will do the job.
thank you for all the responses. please bear with me through a lot of questions. can i replace te uf4007 by 1n4007 in power supply? thanks again guys. Highly appreciated.
If you talk about diode in SMPS, right after the IRF740, then answer is NO, 1N400x series are a lot slower than UF400x, so it will not work as expected. It will oscillate more in basic frequency and have some parasitic oscillations, so I wouldn't suggest you to do that.
thank you so much sir Rankot. A very big help indeed.
The 1N is really slow the UF is ultra fast, you will need at 30kHz. :)
(http://i1249.photobucket.com/albums/hh520/johngovan1234/HV%20Layout_zpsagyv9olj.jpg) (http://s1249.photobucket.com/user/johngovan1234/media/HV%20Layout_zpsagyv9olj.jpg.html)
here is my current layout for the power supply. im just waiting for the inductor. Thank you for all your help. My build is so slow because of the availability of the components.
credits to sir vigilante397 circuit.
(http://i1249.photobucket.com/albums/hh520/johngovan1234/2018_0913_16144900_zpsquq3r1cz.jpg) (http://s1249.photobucket.com/user/johngovan1234/media/2018_0913_16144900_zpsquq3r1cz.jpg.html)
Currently waiting for the components. Thanks for the help.
Quote from: johngovan1234 on September 12, 2018, 11:56:34 PM
credits to sir vigilante397 circuit.
As much as I enjoy taking credit for things, that circuit has been around for a looooooonnnnggg time even before I started building. Layout looks good though! ;D
Well done :) This seems to going well 8)
Please correct me if i am wrong. I will connect the pins 4 and 5 together and put a 6.3v positive and the pin 9 to the ground?
Yep. Merlin has a neat picture on his website:
(http://www.valvewizard.co.uk/heater1.jpg) (http://www.valvewizard.co.uk/heater.html)
Thank you bluebunny. :) that helps a lot
Cant belive this thread has 4 pages already. ;)
Quote from: MJ_Sound_Cubed on September 18, 2018, 05:35:47 PM
Cant belive this thread has 4 pages already. ;)
Just wait for Rob (deadastronaut) to post a new thread, like "I just had an idea for a new project..."
Before you know it - twenty-six pages! :icon_eek:
Let's make it 10 pages. Hahaha.
I hooked up everything and it makes a decent sound. But i dont know why the regulator for the 6.3v heater gets hot and i hear some squeals when there no guitar plugged in. I replace the 12ax7 but the high pitch squeal is still there. I also have grid stopper resistor on the first and second stage.
If you use only one tube, then regulator will dissipate 0.3*dV, so if you have 9V DC at the input and regulate down to 6.3, it will be 0.3*2.7=0.81W of power. It will require 15K/W or less declared heat sink. If you use two tubes, it will be 9K/W. However, it also depend on your input voltage, so take this only as a hint.
For the squealing with nothing plugged in - I would always used a switched input jack socket. The tip will be grounded without a cable plugged in it by the built-in socket switch. Almost every guitar amplifier does this. It stops the amp picking up stray noise as the high input impedance of the tube grid is highly sensitive.
(http://www.ampmaker.com/store/images/sk10c.jpg)
In this photo, you can see...
Screened cable used. If the tube and socket are not mounted on a pcb, I would use screened cable for the input if practical.
1M grid resistor mounted immediately on the socket. More for convenience in wired assembly, it doesn't have to be put right there.
Wire link across from tip contact switch to ground. So the input grounds with no plug in.
> i dont know why the regulator for the 6.3v heater gets hot
You got 9V. You need 6V. Where does the other 3V go?
When I cut 9 foot lumber to 6 foot I get a heap of 3 foot scraps in my way.
Here, the excess 3V doesn't lay on the floor to trip over, thank goodness. Instead it "goes away" as heat.
3V at 0.3A is nearly a Watt. 1 Watt in a TO-220 package may be safe but sure is HOT. Normally we'd bolt the regulator to a heat spreader at about this point. But it may live forever, naked, if it gets good air.
If you have stuck to your first post and use one tube, then you need 15°C/W or better declared heat sink for your heater voltage regulator. Or you may simply use 9.1 ohm 2W resistor in series with heater, connected directly to 9V, and omit whole heater regulator circuit. I vote for this option.
You are awesome guys. Your responses are very helpful and i learn a lot.
This is what i did. I remove all the bits and pieces of my project. Rewire everything and it seems that the sqeals comes from the gain wire and thr input wire which i use sheilded. And i follow anotjerjtm advice to groind the input using a switch jack. And it do the trick but i think i see the biggest source of the squeal. It comes from the ceramic treble cap in the tonestack. Then i bend the leads and push it down kinda right angle. The squel becomes so little.
I also make the chassis my heatsink as of now. I'll post pic when i finish this. :)
(http://i1249.photobucket.com/albums/hh520/johngovan1234/15378384718981379840906_zpspqkdxmlg.jpg) (http://s1249.photobucket.com/user/johngovan1234/media/15378384718981379840906_zpspqkdxmlg.jpg.html)
So far. This things goes. I have 2 boards made. 1 with cathode follower and one is the typical 1st stage tone stack 2nd stage design.
What i've learned is the conventional design sounds weak, i think because it needs a 3rd stage to compensate for the loss of the tone stack.
My other question is, how can i modify the smps supply to receive 19v (laptop psu) i' just trying out some posibilities here. Thank you for all your help. Please have patience with me.
For fewer problems with instability (squeals) and noise, pop the grid wires up in the air, and keep them as short as possible. Keep the plate and cathode wires pushed down against the chassis. The wires to the tone controls might like to be pushed against the chassis as well.
Quote from: thermionix on September 25, 2018, 12:38:39 AM
For fewer problems with instability (squeals) and noise, pop the grid wires up in the air, and keep them as short as possible. Keep the plate and cathode wires pushed down against the chassis. The wires to the tone controls might like to be pushed against the chassis as well.
Thank you. I keep this in mind. And try to apply it this time around. I' doing my 3rd board. The first has to much noise. The second with a different circuit is very weak. I hope this 3rd try i get the sound i was looking for. :)
Quote from: PRR on September 20, 2018, 11:10:18 PM
> i dont know why the regulator for the 6.3v heater gets hot
You got 9V. You need 6V. Where does the other 3V go?
When I cut 9 foot lumber to 6 foot I get a heap of 3 foot scraps in my way.
Here, the excess 3V doesn't lay on the floor to trip over, thank goodness. Instead it "goes away" as heat.
3V at 0.3A is nearly a Watt. 1 Watt in a TO-220 package may be safe but sure is HOT. Normally we'd bolt the regulator to a heat spreader at about this point. But it may live forever, naked, if it gets good air.
This is so clear. Thank you Sir. Now i get it right. Thanks for the help. :)
Quote from: johngovan1234 on September 25, 2018, 10:03:35 AM
Quote from: thermionix on September 25, 2018, 12:38:39 AM
For fewer problems with instability (squeals) and noise, pop the grid wires up in the air, and keep them as short as possible. Keep the plate and cathode wires pushed down against the chassis. The wires to the tone controls might like to be pushed against the chassis as well.
Thank you. I keep this in mind. And try to apply it this time around. I' doing my 3rd board. The first has to much noise. The second with a different circuit is very weak. I hope this 3rd try i get the sound i was looking for. :)
Another thing for future builds, and I can't see all that is going on in the pic, but it looks like you're basically crossing over the tube, wires running to the farther triode relative to the circuit on the board. So it might reduce problems to swap triodes. General rule of thumb is to not have the signal path cross over itself, but to flow from input to output, as much as possible.
Cross wires at 90 degrees from each other. Keep them short if possible, think of them acting either as an aerial or transmitter antenna, they work best when longer related to the size of the wavelength. Also think in terms of loops, the input circuit loop, the output circuit loop. With that in mind the area that the loop makes catches interference in relation to the size of the loop. Think of it as a net. Of course optimizing one area will compromise another (we can't win every battle). Knowing which one to optimize separates the men from the boys.
(http://i1249.photobucket.com/albums/hh520/johngovan1234/20180926_195915_zpsenfonid2.jpg) (http://s1249.photobucket.com/user/johngovan1234/media/20180926_195915_zpsenfonid2.jpg.html)
This is my current wiring. I think i need to layout the board in more organized way. I hear no squeal or noises as of now even at max gain. But i will test it more and see if there is any problem that will arise. Thanks for the tips..:)
So the progress is almost there. But a new struggle arise. Haha. No more squeal or loud hum. Thanks for the wiring tips of thermionix. It really helps me quiet down my preamp noises. But this is my problem. I tried to hook my preamp directly to my audio interface but it clips like crazy. I try to lower down the gain and lower the master volume in my preamp, it is as quiet as night but when i put a bit of a volume and gain it clips even a little volume increase.
My amp typology is like a marshall preamp. What could be the cause?
I found the problem. Its a wrong pot wiring. Wew. Now i'm trying to record the sound. I will post a sound demo when all are in good running condition. :)
I would clean the solder joints with alcohol to remove the flux. I will turn another color one day and look a bit disgusting :)
Quote from: MJ_Sound_Cubed on September 27, 2018, 05:10:24 PM
I would clean the solder joints with alcohol to remove the flux. I will turn another color one day and look a bit disgusting :)
Thank you sir MJ. I'll post the clips as soon as possible. My habds are not yet ready to play.
https://soundcloud.com/john-govan-426812247/amp-problem
I have this problem in my sound. There's an ugly distortion or clipping. I dont know why.
Overdriving your audio interface?
I dunno, it sounds like its trying to be good, but I don't think it's clipping the recording. I can hear a fizzy "digital" crackling in the note decays which is present in the silence at the end. I mean "digital" as a description, sometimes it can be something unexpected, like the treble cap in the tone stack... to something actually digital like multiple SMPS noise in the grounds...
Could you hear anything wrong while recording or only afterwards on the recording?
Quote from: anotherjim on October 02, 2018, 04:11:10 PM
I dunno, it sounds like its trying to be good, but I don't think it's clipping the recording. I can hear a fizzy "digital" crackling in the note decays which is present in the silence at the end. I mean "digital" as a description, sometimes it can be something unexpected, like the treble cap in the tone stack... to something actually digital like multiple SMPS noise in the grounds...
Could you hear anything wrong while recording or only afterwards on the recording?
i can hear it even i hook my preamp into the power amp of my guitar amp. i think it is my wiring. or i'll try to replace my treble cap since it is a multi layer cermaic. i think it is not a good treble cap. Mica caps are pretty expensive. thank you sir.
Quote from: johngovan1234 on October 03, 2018, 07:06:36 AM
Quote from: anotherjim on October 02, 2018, 04:11:10 PM
I dunno, it sounds like its trying to be good, but I don't think it's clipping the recording. I can hear a fizzy "digital" crackling in the note decays which is present in the silence at the end. I mean "digital" as a description, sometimes it can be something unexpected, like the treble cap in the tone stack... to something actually digital like multiple SMPS noise in the grounds...
Could you hear anything wrong while recording or only afterwards on the recording?
i can hear it even i hook my preamp into the power amp of my guitar amp. i think it is my wiring. or i'll try to replace my treble cap since it is a multi layer cermaic. i think it is not a good treble cap. Mica caps are pretty expensive. thank you sir.
Film caps are the best deal for audio and they are normally cheap.
SMPS noise is a problem that takes effort to understand and fix and frequently it helps to sacrifice a goat to the EMI gods. Start with figuring out what the SMPS circuit does and figure out some filtering for it.
At this exact moment, I'm building an Alembic F2B and having noise issues, like static noise. Did this happened in your previous builds? I'm using the same smps, so we may be having the same issues.
Quotei think it is not a good treble cap. Mica caps are pretty expensive. thank you sir.
I found that a good cap for that role is surprisingly difficult to source. Mylar/Mica/Polystyrene in 100-400pF range with sufficient voltage rating - either very expensive or just not listed, at least at many hobby electronics suppliers. I've found ceramic disc caps with 1kV or 2kV ratings can work well, despite not ideal audio types, they have more than enough voltage handling. For the rest of the caps in the nF ranges, they are cheap and very easy to find as film caps with at least 400v rating.
BTW, the scheme may call for 250pF and you can only find 220pF, it will work fine as a tone control.
You can always put HV coupling capacitor before the tone stack, than you can use low voltage capacitors inside it.
> ceramic disc caps with 1kV or 2kV ratings can work well, despite not ideal audio types
Ceramics under 1,000pFd will be "NP0" which is totally perfect and fine for audio. 500V is enough for tube tonestacks.
You can get NP0 in larger values but typically not at tube voltages.
There are Tube Guitar Amp web-shops who stock the usual tonestack parts in appropriate ratings and values.
Based on your help and informations and the forums i read. It really helps a lot in my learning. Let me share the learning i get from all of you and from reading forums and discussions of other peoples build.
1. Google search engine is very helpful
2. Tube amp DC Voltage will shock you to the bones if you accidentaly touch the B+. 😁
3. WIRING is so crucial! Yes. You guys are really awesome. Wiring tube amp is far more sensitive than wiring a guitar pedal. An understanding of each wires are really important.
As stated by one of our fellow, make sure that we minimize wires crossing each other in the tube connections. The most troublesome wire is the grid wire. We must use a good shielded wire in this triode pin. Because this gives a lot of noise and those nasty tube overdriven artifacts.
4. Grounding is also very important. Don't forget the star ground and be aware of ground loops.
5. I love youtube tutorials.
6. Capacitor are important to what kind of caps to use. Mylar and poly are good for audio. Ceramics are as much as possible be avoided. They are sensitive to thermal changes and suceptible to piezo effect. Sometimes it becomes a noise anthena. Mylar or Mica or NP0 are good choices.
7. Measure voltages and understand basic functions of what you are doing. Learn how tube functions, how capacitor functions, how resistor fuctions and everything. My downsides are computations and other terminologies i do not know. I'm no engineer nor an electronic expert. I learned things tru forums, and internet searchings.
And many more things i've learned in this forum. I will continue to update as soon as everything is in good shape..as of now, the nasty tone are gone. It is a wiring and capacitor issue. :)
> Ceramics are as much as possible be avoided.
"Ceramic" covers a w-i-d-e range of stuff.
Think of a baked clay flower-pot versus the glaze on a fine dinner plate.
A 0.1uFd, even 0.01uFd, has historically been a "salted" ceramic, like X7R or Z5U, with funny adulterants to raise the value per unit of space. These high values tend to vary with voltage, temperature, and mechanical stress.
A 1,000pFd or smaller can be made with a "glass-like" ceramic which really is good as glass (but easier to make thin) and shows very-low variation. Under 1,000pFd there's no reason to use "salted" ceramics, the pure stuff is small and cheap. FWIW, small ceramics are good-enough for the Jensen 990, a very high-quality audio studio op-amp.
Quote from: PRR on October 06, 2018, 12:30:39 AM
> Ceramics are as much as possible be avoided.
"Ceramic" covers a w-i-d-e range of stuff.
Think of a baked clay flower-pot versus the glaze on a fine dinner plate.
A 0.1uFd, even 0.01uFd, has historically been a "salted" ceramic, like X7R or Z5U, with funny adulterants to raise the value per unit of space. These high values tend to vary with voltage, temperature, and mechanical stress.
A 1,000pFd or smaller can be made with a "glass-like" ceramic which really is good as glass (but easier to make thin) and shows very-low variation. Under 1,000pFd there's no reason to use "salted" ceramics, the pure stuff is small and cheap. FWIW, small ceramics are good-enough for the Jensen 990, a very high-quality audio studio op-amp.
Thank you PRR for clarifications and corrections. I'll take note of this and continue to study more. I think my statement is too general about caps. A big enlightenment indeed. :)
I was finding the ceramic discs as the usual dull baked clay form - maximum 100v in NPO. Then a jump to at least 1kv with a shiny dipped coating. Nothing at all in between.
This 2kv YP5 type...
https://www.rapidonline.com/suntan-ts16003d221ksbpb0r-220pf-10-2kv-y5p-ceramic-disc-capacitor-08-1538
Replaced a Mica that should have been ok, but was doing a very good imitation of a conch shell to the ear as soon as things warmed up.
But anyway, here's an example Mica that should be perfect. Price isn't way huge, but is high compared to most passive components...
https://www.rapidonline.com/suntan-ts23002h221j3b000r-220pf-5-500v-silver-mica-capacitor-12-0057
> ceramic discs as the usual dull baked clay ........ 1kv with a shiny dipped coating.
The outside stuff is NOT the dielectric, just something to hide the raw guts.
The dielectric runs from NP0 (En Pee Zero) which is nearly perfect, to X7R which _I_ can sometimes hear in a preamp, to Z5U which is pretty dubious stuff.
Silver Mica is as good as it gets. However the page you linked shows a 100V 100pFd poly cap for a much lower price. Rapid's site discouraged me from finding a higher-V version of the same thing.
Yes, Rapids parametric search only works properly within types of cap, not all caps.
However, I just tried the page header search simply for "220pF capacitor", got all types of that value. Then got parametric selection on the sidebar. Picked all the HV options and found this...
https://www.rapidonline.com/wima-fkp2j002201d00hs-fkp2-220pf-2-5-630v-radial-polypropylene-capacitor-64-2491
Not an ideal package either for tag/turret or build-on-pots construction. Those Wima caps are usually supplied with very short legs.