I started playing around with my breadboard on a mesa boogie schem - the 12ax7 doesn't sound good with the changes I made, but it's good with a 12au7.
It uses 12V to power the heaters and 50V on the plates - I used the voltage multiplier I built, you can find it here -->http://w1.859.telia.com/~u85920178/power/vconv_01.htm
I made some changes, took out some components, and gave it a cool name...it's just a 5 minutes build now, so I guess there are some minor changes to be made, but it sounds good even at this stage...
In my breadboarded version I didn't put the final 25n cap...
So here it is, version 0.1
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=39106&g2_serialNumber=1)
whats wrong with the 12ax7? i like the look of this circuit... Lone star?
Hi, Nice looking circuit there, i will have to breadboard this one and try it out. I have one question though, in the schematic you have the 1n and 560k resistor that are parrallel between valve stages shorted out with a wire . Have i misread the schematic ?
Nice! What sort of tonal characteristics does it have? is it clean or crunchy? I like the looks of this.
Quote from: Ice-9 on March 11, 2009, 05:43:22 AM
Hi, Nice looking circuit there, i will have to breadboard this one and try it out. I have one question though, in the schematic you have the 1n and 560k resistor that are parrallel between valve stages shorted out with a wire . Have i misread the schematic ?
My guess is that where there is the wire there is supposed to be a gain pot, but I definitely don't think there should be a short. But other than that, it is a nice looking circuit.
yep, that shouldnt be... but i might be the 2m2 resistor that acts like a gain pot that was maxed...
the cathode bypass capacitor is in series with a 47k resistor... i think the 47k resistor will null any effects of the bypass cap in the audible spectrum. correct me if im wrong...
The 47k resistor will simply limit the difference between the treble and bass response. So instead of being maybe 6 or 7 dB, it will be more like 3 or 4 dB (where the treble is higher than the bass). I actually have that resistor that can be bypassed with an spst switch on my current tube project, it is great for a little flavor change.
What a coincidence. I was playing around on LTSpice yesterday and came up with something very similar. I was simulating a valvecaster type unit run on 36 volts(four 9 volt batteries is the plan) and I came up with similar values as you except no 47k in series with the bypass cap.
thx for the replies - Let me point you where it all began...this is a stripped out and modified version of the mesa boogie preamp you can find here--> http://www.freeinfosociety.com/electronics/schematics/audio/pictures/mesaboogiedualrectifier1.gif
It has a good crunch, not the metal distortion I wanted but hey it's so nice - you can add a pot for the gain, I just went over it...
I tried all the combinations on the first cathode, like 2k2+1µF, 2k2+47k, 2k2+47k and 1µF, 47k alone, 1µF alone, 47k+1µF
No big differences, but hey you can try them....
On my project I recently swapped out the 1k8 cathode resistor for an 820R and it added a little more saturation to it. I think that a general rule is the lower the cathode resistor value, the more gain you will get, but then again, I just started in on these things.
That partially bypass cathode cap on the first stage has a pretty big limiting resistor.
From my experience 1K - 15K work best with 12AU7 designs like this.
I'll try that tonight
Also, the original res on the second plate was 100k, but 47k seemed a little better to my ears...
Neat see you experimenting Adriano. A few observations:
Is that a short between the two stages, or a mistake in the schematic?
It's more usual to have the grid leak resistor (2M2) the other side of the grid stopper resistor (470K).
The grid stopper seems a high value, tubedummy: Values can be 1.5K->100K. Larger values roll off more highs and reduce gain between stages.
Why no input cap? Did you try it with one?
So maybe add an input cap, get rid of the short, move the 2M2 to right next to the grid, and in it's place have a 1M interstage gain control, and have a play about with the value of the grid stopper.
:icon_biggrin:
Input caps is usual for non-tube projects.
There is possible an input resistor - 33-75K.
Checked back the breadboard, yeah I should remove that line from the schematic...
Tried to follow some of your hints before I finally go to bed...
german, tried a 47k res. between the input and pin 2 - no big deal...
tried other res. value with the cathode cap - no big deal too
finally I got rid of the cathode cap/res. couple...
lowered the remaining res. to 470r - thx Ripthorn
tried to move the 2m2 res. after the 470k - no big difference...
Updated and added a quick sound sample
(http://www.aronnelson.com/gallery/main.php/v/Renegadrian/Tube+Star+1.mp3.html)
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=39106&g2_serialNumber=3)
That sounds really great, Adriano. Was that clip through an amp, cab sim, or direct? I think I may have to pick up a 12au7 and give this thing a shot. It may have to wait, as my submini amp is taking a lot of time and I want to make sure I do it right.
I like the fact that you have no capacitor bypassing in either stage, and that you're using a quieter hi-fi tube ...
good job !
Brian, the clip was (quickly) recorded with this setup...
Guitar-->Tube Star-->PC audio card. No amps or amp simulators.
Maybe I'll see if I can plug it into an amp when I come home from work...
thx to everybody for the nice words and suggestions...
You know, you actually inspired me to give this a shot, so I just bought a lot of 6 12au7's on ebay. They were cheap and I have some 6aq5's hanging around, so I have pedal and amp possibilities galore. This is definitely going on the board as soon as the tubes come.
That sounds really great! I'll have to breadboard this guy as well. Good thing I have one spare 12AU7 in my closet.
Tweaked the circuit a little more...I think I will experiment a little more with the 12AT7, it made me forget about the AU7...
Lotsa more gain!!! And Hell knows how much I am after HIGH GAIN devices...Man, this Star SCREAMS!!! :icon_twisted:
I tried the conventional "GAIN" pot wiring (which actually is a volume control between the two stages...) but liked the variable resistance on the first cathode better...So I went with it...
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=39174&g2_serialNumber=1)
crackle OK ? :icon_biggrin:
Ya thats what I was thinking...
Ditch the variable cathode resistor and either add a gain pot in between stages, or have a high/low cathode resistor switch.
Quote from: snap on March 15, 2009, 01:25:18 PM
crackle OK ? :icon_biggrin:
I've never actually read about this, but is the crackle just when adjusting the pot value, or does it crackle the whole time? I only ask because I have a variable cathode resistor on my breadboard, and if this causes some noise or something, I may rework it.
Adriano, looking great, I look forward to hearing clips with the AT7, I am just a little disappointed because I guess I jumped the gun and already ordered AU7's. :icon_rolleyes: Oh well, plenty of good stuff with those, too.
It just crackles when you turn the knob.
Actually it rarely cracks, after all I just put the gain as it is in the Valvecaster. Nothing that shouldn't be done at all...I know that the usual way is to wire the pot between stages, as a MASTER (I wouldn't call it gain, actually it's more than a volume at the end of the first stage) but you know, that seemed more useful to me...
Brian, the first schematic on this topic, at the previous page, uses a 12AU7 at its best (or at MY best!!! :icon_redface:)
Basically you have a good hot overdrive (running it at 48V or more). You can choose to have
a) no gain control
b) the gain at the first cathode, Valvecaster style
c) the usual MASTER control between the two stages.
As you heard on the quick clip I recorded of it, it is quite gainy, but you know I am an ol' METALHEAD (http://www.sevenstring.org/forum/images/smilies/Zork-Metal-Smiley.gif) so I just wanted more...Up to eleven!!!
So expect a gain monster from the other schematic (the 12AT7 one)...
12AU7 TUBE STAR - NO GAIN (http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=39106&g2_serialNumber=5)
12AU7 TUBE STAR - CATHODE GAIN (VALVY STYLE) (http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=39235&g2_serialNumber=1)
12AU7 TUBE STAR - MASTER VOLUME (http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=39237&%3Cbr%20/%3Eg2_serialNumber=1)
It's funny you mention up to eleven. In the amp I am working on, I have a footswitchable triode boost in front of the preamp (built into the amp) and the front panel label for its gain control is "Eleven". :icon_twisted: Anyway, I did quite like the sound of the AU7 one, so I will build that (As much as I would like to try the AT7 version, let's be honest, I probably have enough high gain pedals, if such a thing is possible). I kind of like the cathode gain control. I think the breadboard needs a little more attention on that matter.
Adriano - your soundclips are very cool, great sound, nice chops!
I'm just loving it that there is a renaissance of tube circuits right here right now on this forum. People have built the Valvecaster and are moving on and experimenting with their own designs. Lovin' it!
Yeah it's the TUBE RENAISSANCE and we're just deep in it!!! :icon_cool:
Yeah, it is funny how people on the outside would see us as using "inferior" technology. I talked to my filter design professor about something and he said "But that is going to distort the signal" and I said "I know, it's for electric guitar" and he just said "Oh" :icon_lol:. When I have my designs a little more firmed up, I will share them, but for the time being, I will enjoy the designs of you guys posted here.
Added a couple of Vero layouts. The "Master Volume" layout will be online soon...
TUBE STAR (http://www.aronnelson.com/gallery/main.php/v/Renegadrian/Tube+Star+0_4.gif.html)
TUBE STAR CATHODE GAIN (http://www.aronnelson.com/gallery/main.php/v/Renegadrian/Tube+Star+0_4-+cathode-gain.gif.html)
Cathode gain is bad thing - becose you change tube bias.. all gets cranked up.. Or pot value could be about 0-2K2..
Only mastergain style between two triodes is accepted.
Yes cathode gain changes the bias, but as long as it is within normal limits, I don't see a problem with it. For example, I have a cathode bias booster that has a small resistor in series with it (so that the cathode never goes to ground) and it works fine. Tubes are meant to be run at different biases, that is what is great for guitars.
I think that the volume control between triode stages is good for general use, but it can be nice to have things a little different once in a while.
Quote from: Ripthorn on March 25, 2009, 08:06:51 PM
For example, I have a cathode bias booster that has a small resistor in series with it (so that the cathode never goes to ground)
This is a good idea, I've mentioned a few times the audible thunk of the Valvecaster as gain control is turn to maximum. Valvecasters can also whistle when bypassed when at maximum gain. A 1K resistor would do it - what did you use Brian? I have to say though, I do prefer fixing the bias and using an interstage gain control.
The value of the resistor really depends on how much umph you want out of the thing. I use a 470R if I want really high gain and 820R or 1k8 for slightly lower levels. I choose the values depending on what I want and I got them from looking at amps like Mesas, Marshalls and other high gainers. I do prefer the interstage control for most situations, I am just saying that I think a variable bias has its place and I think that for a booster that is not always in use, it is not a bad way to go (though I think I am going to make a back panel control for an interstage control on the boost just because if I want it to boost the clean channel, it gets a lot louder than if I boost the dirty channel, perhaps a trimmer).
I am just totally digging all the tube stuff going on here, lots of great ideas going about. I look forward to seeing your Promiscuous Girlfriend, Rick ;), though i was thinking you might want to consider some terms like hussy or fluzie (you come up with the greatest names to go with your projects).
Quote from: Ripthorn on March 25, 2009, 08:30:36 PM
I look forward to seeing your Promiscuous Girlfriend, Rick ;),
Brian, out of context, that comment seems inappropriate! :icon_mrgreen:
Quote from: Ripthorn on March 25, 2009, 08:30:36 PM
(you come up with the greatest names to go with your projects).
Thanks - I design the names first, then come up with a project to fit the name!
Then I almost hate to ask you what the inspiration was for this upcoming project :icon_eek:
I know that cathode fain is not the common way, but I found that it could be used without issues...
So German, I made 3 schematics and there will be 3 layout, with a fixed gain (just a resistor to ground), with the typical "master volume" between stages and the cathode gain pot, as seen in the Valvecaster too...
So German, if you are so strict about that, you can go with the classic way...Else, I have to tell you that I breadboarded all the 3 versions, and the cathode gain is a good solution, no strange crackles or issues...It works good, at least for me, and I found it more useful (it acts more like the gain control I was after) than the volume pot that is between the triodes.
Quote from: Ripthorn on March 25, 2009, 08:06:51 PM
Yes cathode gain changes the bias, but as long as it is within normal limits, I don't see a problem with it. For example, I have a cathode bias booster that has a small resistor in series with it (so that the cathode never goes to ground) and it works fine. Tubes are meant to be run at different biases, that is what is great for guitars.
I think that the volume control between triode stages is good for general use, but it can be nice to have things a little different once in a while.
Yeah!!! :icon_wink:
Adriano, like the sound clips. If your trying to get that scooped metal tone that Recto's are known for, add another tube for two more stages. It makes it a lot easier to taylor the circuit for the exact sound you want. Going one stage at a time you can really dial it in. At the higher voltage you can almost duplicate a red channel tone.
I think I am going to build something more difficult one day, like a 2 stages pre or something - For now I follow the "LESS IS BETTER" approach, so keep parts count low for an easy circuit...And the sound I have with this lil' monster got me :icon_eek:
Gotta make some other 12AT7 experiments...
Also I think I'll end using trafos and such things one day, but for now that simple voltage multiplier works so good - I really find the tubes are working so good at the +-50V I am running them...
THX for the hint, Jered...I appreciate that... :icon_wink:
Looking forward to building this!
Quote from: Renegadrian on March 11, 2009, 02:58:22 AM
I started playing around with my breadboard on a mesa boogie schem - the 12ax7 doesn't sound good with the changes I made, but it's good with a 12au7.
It uses 12V to power the heaters and 50V on the plates - I used the voltage multiplier I built, you can find it here -->http://w1.859.telia.com/~u85920178/power/vconv_01.htm
Did you build the multiplier on a veroboard, or did you use the PCB layout on the website?
Nice to see you're interested!
I used that layout on the site, only on a perfboard.
It should go at 48V, but as the WW is not regulated, it gives something more than 12V, so I got more or less 50V.
Hey Renegadrian
I build the ecc82 version, gave it an input cap and run it at 78 volts on the anode. Cool sound both on my 5 Watter and my trusted Laney VC30.
Ciao
Quote from: Renegadrian on December 03, 2009, 04:40:07 PM
Nice to see you're interested!
I used that layout on the site, only on a perfboard.
It should go at 48V, but as the WW is not regulated, it gives something more than 12V, so I got more or less 50V.
I don't suppose you have a diagram for your perfboard layout still?
Quote from: MichelP on December 04, 2009, 11:03:12 AM
Hey Renegadrian
I build the ecc82 version, gave it an input cap and run it at 78 volts on the anode. Cool sound both on my 5 Watter and my trusted Laney VC30.
Ciao
Wow, nice to have such a good word! Thx for trying it out!!!
Quote from: letterbeacon on December 04, 2009, 11:59:38 AM
Quote from: Renegadrian on December 03, 2009, 04:40:07 PM
Nice to see you're interested!
I used that layout on the site, only on a perfboard.
It should go at 48V, but as the WW is not regulated, it gives something more than 12V, so I got more or less 50V.
I don't suppose you have a diagram for your perfboard layout still?
Sorry, I don't get what you are asking for...I posted both the schems and the vero layouts.
Gonna build this one....hey, anyone know why on LTSpice, I have to move the 2nd stage grid leak to the RIGHT of the 2 470K grid stoppers in order for it to simulate? Won't do it for me if I have the 1M as it's posted. Odd!
THX
Mike
dunno Mike, I usually let the ears be the judge, and they say that my layout sounds good (at least for me and enough to share...), also LTspice is a stranger to me...
Quote from: Renegadrian on December 04, 2009, 07:52:56 PM
Quote from: letterbeacon on December 04, 2009, 11:59:38 AM
Quote from: Renegadrian on December 03, 2009, 04:40:07 PM
Nice to see you're interested!
I used that layout on the site, only on a perfboard.
It should go at 48V, but as the WW is not regulated, it gives something more than 12V, so I got more or less 50V.
I don't suppose you have a diagram for your perfboard layout still?
Sorry, I don't get what you are asking for...I posted both the schems and the vero layouts.
Apologies, I mean do you have the layout for the voltage multiplier that you built on perfboard?
Yeah, you don't know until you build. I wanted to see how the clipping is working with your Tube Star, so simmed it up quickly. Simulation is for general 'ideas' of what might happen, at best! The old way was to have the grid lead right at the grid, stopper first....but that attenuates the signal a little. Simulators have a problem with moving it 'left' of the stopper, which is the best way to do it. Don't know why.....
Renegadrian, could you please post a schematics or layout for the power supply - 12 - 48V?
Thanx!
Quote from: ca cat on March 21, 2010, 07:20:39 AM
Renegadrian, could you please post a schematics or layout for the power supply - 12 - 48V?
Thanx!
I think he used this one:
http://www.sm0vpo.com/power/vconv_01.htm
http://www.diystompboxes.com/smfforum/index.php?topic=74088.0
EDIT: Link fixed!
Yes that's it!!!
Sorry, but i don't understand one thing: how can i provide 12V to the tube and B+ (48V and more) at the same time ?
In particular, i would like to know which tube pins go to 12V (i would use a 7812, right?); i suppose that placing 48V and more on B+ is more obvious (to the resistors before pins 1 and 6)...
Can i do this with any kind of low voltage circuit ? Even with the Valvecaster (that i just built yesterday) ?
Thanks !
You have to separate the voltage just after the WW socket on the pedal. So you have two wires, one going to the heaters and one going to the voltage multiplier.
On a double triode, you apply voltage to the heater (12V in the 12**7 family) to pin 4 and 5. one gets + and one gets - (in one direction or another)
7812 is mandatory if your wall wart is not regulated. B+ goes to pins 1 and 6, correct.
Yes, Valvy can use this setting too...
hope I am not waking a ghost, but I am gonna build this soon. Probably need a tall large enclosure with room to hide the tube. I dont want my tube sticking out. It might get brokeded. Or maybe get beer on it at the rock 'n' roll punk rock show. Can't wait till I get money to order again. :P
Nice you have interest in my tube circuit! you like tubes, don't ya!? :icon_lol:
Report on this one and all the others!!! And have fun with those glasses!!!
Wiping the dust off of this one...
Is there a FINALIZED layout of this circuit anywhere? I know there are a few within this thread however, I want to know if there is an end-all/be-all version that has all of the details worked out.
Or even a PCB layout anywhere ???
Thanks ;D
What are the current requirements from a 48v supply for the plates? I have a PSU for a mic preamp that should work for this.
The plates need a few mA, as some other circuits around. It's the heaters that need more current, at least ½ A or better 1A to avoid any hiss/hum.
@ Govmnt_Lacky - there is not a FINAL version, as I tried all the options there - no gain, gain as interstage volume, gain at the first cathode a la Valvecaster, and swapping tubes (AT an AU) - All of them work! I like the cathode gain best, as it acts more like a SS gain regulation, while the interstage volume just cuts the amount of signal going to the second stage, it's a standard solution found in almost all amps/preamps but...maybe in this ckt you can go with the cathode gain.
Any sound samples of this?