Tube boost + overdrive running off a 9 volt battery

[iccaros]

I started work on a *yipes* quadcaster tonight.  I used two twincaster vero layouts next to each other.  I am building it for bass, so I am socketing the input and coupling caps along with the anode and cathode resistors.  I'm going to try the stock valvecaster values first, then try the valvemaster values and see which sounds better.  I am making a couple of mods- I am using a 500k gain pot in between the first and second gain stages instead of the standard 50k pots on the cathodes.  I'm also considering making a switchable JFET buffer stage at the input because I have an active bass, but honestly I don't even think I need it.

I ordered (3) JJ 12AU7s and (1) JJ 12AT7.  I will be using this on bass and I really like the way JJs sound in my bass amp.  I might try the 12AT7 in V1 to see what happens, I really want to go for higher gain. 

I am taking photos and will post a build report when finished just in case anyone wants to build one.  I'll also work on sound clips.  Eight gain stages.... even though they're not high gain tubes it should still be fun!

that is a lot.. Like to see if you get any clean after that..
I also like using a small pentode after the single valve caster.. 
Its not a bass but you get lots of gain -->

[runmikeyrun]

that's awesome!  I would love to do something like that but i'm being lazy and don't want to do HV... I like the simplicity of the LV circuit.  Besides i'm trying to finish a tube amp project and that's giving me enough potential to get electrocuted

[iccaros]

that is 12v... no HV... look up lonewolf for the pentode part.. I posted a project that put a different valve caster with the lonewolf, I uses a 6au6 and a 12ax7.. see a few pages before..

[runmikeyrun]

Oh great, now I have to build ANOTHER tube pedal after this one    Seriously, thanks for the info, I will check into it.

[Yeahno]

For my third pedal project, and apparently because I am a glutton for punishment, I breadboarded the ValveMaster up. 

But because I have limited electronics experience, I made a few missteps (like, I suspect, interpreting the tube symbol as shorting pins 4 & 5 on the tube).  Went over the circuit with a fine tooth comb, even going so far as to pull it and do it again.  No parts subs except for the use of an ECC82 tube (which I'm lead to believe is a thin-plate variant of the 12AU7).  I get no output and I don't see the tube light up (I'm not even sure that I should, frankly).

I think I must be interpreting the schematic incorrectly though.  Just looking for confirmation of some of my assumptions and interpretations.

1. The ground of the input and output jacks connect to the ground rail?

2. VR1 pin 1 goes to C2, pin 2 to tube pin 7, pin 3 to ground?

3. VR2 pins 2 and 3 are soldered together and the result goes to ground?

4. Output jack comes off of pin 2 on VR3?

5. Power supply can be a simply 9VDC battery? Or do I have to use something with more current?  If I use a 12VDC/1A supply, will I harm the circuit?

6. Tube pins 4 & 5 should not be shorted to each other?

7. 9VDC negative goes to the ground rail, right?

[frequencycentral]

1. The ground of the input and output jacks connect to the ground rail? Yes

2. VR1 pin 1 goes to C2, pin 2 to tube pin 7, pin 3 to ground? Other was round: 1 to ground, 2 to C2, 3 to pin 7

3. VR2 pins 2 and 3 are soldered together and the result goes to ground? Other way round: 1 and 2 soldered together and grounded, 3 to C4

4. Output jack comes off of pin 2 on VR3? Yup

5. Power supply can be a simply 9VDC battery? Or do I have to use something with more current?  If I use a 12VDC/1A supply, will I harm the circuit? A battery won't last long at all. 12VDC/1A is fine - observe correct polarity

6. Tube pins 4 & 5 should not be shorted to each other? They should not be shorted together. Pin 4 to ground, pin 5 to +ve

7. 9VDC negative goes to the ground rail, right? Yup

[Yeahno]

Thanks for that.

The pots were the wrong way around, but my understanding is only that the should work in the wrong direction, not that the circuit won't work at all, right?

Should I actually be seeing the tube light up?

Cheers,

[frequencycentral]

Should I actually be seeing the tube light up?

Yes there should be a subtle orange glow, it's not a light bulb, so you may have to look for it. Are you sure you are reading the pinout the right way around?

[Yeahno]

I think it would be prudent to check it again.  My reference is http://www.dogstar.dantimax.dk/tubestuf/pinout.htm

Wondering if shorting pins 4 & 5 under power would have damaged the tube.

[Yeahno]

Pins are correct. But where should pin 9 be connected?

[Renegadrian]

Leave pin 9 NC - if unsure of the tube, just have two wires coming off the wall wart (+ and grd) and connect them at pin 4 and 5 (direction doesn't matter) - make sure to count the pins in the right direction, sometimes I do it wrong myself still...with the pins facing you, the gap facing bottom, the pin at the left of the gap is pin 1, start counting CCW.
As Rick said, you should see some light from the heaters - every tube is different from the others, some have a nice glow and some are barely lit. but you should see 2 small orange points at least.
a 12V-1A is what I use and find great for these kind of ckts. I found some very cheap at the bay. (like 3$) and silent!

[Yeahno]

Thanks!  Pin 9 will remain unconnected.

I can just barely see the heaters with 9VDC connected, but they're definitely there.

Clearly, I've mucked this up somewhere that isn't obvious to me.

[runmikeyrun]

just be patient, double check your work, if you get frustrated walk away and come back later.  You'll get it working.  Look on this thread for the voltage readings for each tube and check yours to see if you've got the correct voltages.  Also make sure you've got the tube wired correctly- that you've got pin 1 connected to pin 1 and not pin 9, etc.

Incidentally, I tried a JJ 12AT7 yesterday in my valvecaster, it sounded really good!  A decent amount of grit and more gain for sure.

[Yeahno]

Thanks for the encouragement.

I've checked the pin outs and matched them to http://www.dogstar.dantimax.dk/tubestuf/pinout.htm, which I take to be correct.  And I'm assuming that if the pins weren't correct, I wouldn't be seeing the heaters light up as I do now.

I'm building a ValveMaster, which appears to put VR1 in a completely different place than the ValveCaster.  I'm thinking that perhaps building the ValveCaster would be prudent.

When I've checked everything a couple of times, I simply walk away and plug in the MultiFace or Tube Reamer and bang away for a while.  It's an excellent way to clear out the cobwebs.

Cheers,

[iccaros]

Thanks for the encouragement.

I've checked the pin outs and matched them to http://www.dogstar.dantimax.dk/tubestuf/pinout.htm, which I take to be correct.  And I'm assuming that if the pins weren't correct, I wouldn't be seeing the heaters light up as I do now.

I'm building a ValveMaster, which appears to put VR1 in a completely different place than the ValveCaster.  I'm thinking that perhaps building the ValveCaster would be prudent.

When I've checked everything a couple of times, I simply walk away and plug in the MultiFace or Tube Reamer and bang away for a while.  It's an excellent way to clear out the cobwebs.

Cheers,

can you list the voltages on all pins

also you can use a DMM to check your signal path, connect the guitar or put a signal. place it in AC mode, read the input.. should me millivolts (I see 300mv on mine) with a guitar connected.
check after the cap from the plate of the first stage to the grid of the second.. what do you read ? if you get signal check it at the output.. where you loose signal is where you are having issues.. 

[Bagira]

Thanks for the schematics !
I´m an amateur but finally able to build my first TUBE-preamp(stompbox)

My experiences with first(original) schematic, and first stage changed smaller imput capacitor and 2.step with katode capacitor modification(now 100mikroF) on first catode only:
12V and lately 40V now is better
-ECC82(12AU7) Tungsram       work ,but I think not too good overdrive sound, and too much cut in lows, and no sustain ( lost the sound)
-6N2P(Soviet Ecc83/12AX7)      work, but similar overdrive problems otherhand I like the clean-lowgain sond       (heater voltage 6V)
-E88CC Tungsram                   work, tryed only 12V yet similar like 6N2P most clean sound in lowgain
-ECC85 Tungsram                    Cool overdrive sound now is my favorite but already have  alitle low cut and lost sustain

lately I will upload pictures and soundclips with ECC85

Merry Christmas

[thereminator]

 ECC85 is similiar to ECC81/12AT7, but it has heaters like in ECC88 or 6N2P.

[runmikeyrun]

So I just about have the quadcaster up and running... I need to hit the electronics store to pick up one trimpot and a couple sockets.  I've audio probed it through the 7th gain stage and it sounds AWESOME on guitar and bass.  No sag, no harsh high end, just warm creamy beautiful tube distortion.  How much distortion you ask?  Well, I'd put it somewhere between the Smash Drive and the Tufnel, but obviously does not sound like them.  This is with all gain stages set at max gain and the gain control on 10.  It does clean up nicely at lower gain settings.  This thing produces amazingly thick crunch and sounds incred.  I will try to finish it up in the next few days and get some sound clips, pics and possibly a video plus some notes on the few mods I did.

EDIT:  forgot to mention- i'm using a 12AT7 in V1 for extra gain.  I have a single valvy here and it sounds great in that and really kicks things up a couple notches in the quadcaster.  If you like the tone of the valvy but want more gain try a JJ 12AT7, it sounds great.

[Rick899]

I just built this on the breadboard. I didn't read all the posts in this thread but I read enough to get the drift: This is a "subtle" pedal.  My breadboard test confirms that. Has everyone else  had the same experience?   

My quick eview: With a 9 volt battery that measured 8.9 v (that is all I had; will 9.36 volts really do much more than 8.9v? ) the effect was mild. All the knobs worked. The battery just barely gets the two main tube filaments to glow.  It did seem to give my SS Crate practice amp somewhat of a tube tone and there did seem to be some boost and the mildest distortion.  Nice rich tone. (or was I imagining it?)  After about 15 minutes of playing it brought the battery down from 8.9 v to 8.03 v.

There were some questions about whether this pedal could be played with a 12 volt power supply  but I didn't  read enough to get to an answer.  Has anyone tried this with a 12 volt power supply?   How did it sound? 

Can anyone direct me to any segments of these 133 pages that contain specifically interesting info, esp., like how to modify this  design to run it at 12 volts and get more overdrive from it  ?  Thanks.

[Renegadrian]

COME ON DON'T BE SO LAZY!!! 
YOU WANT INFORMATION, YOU GOT A LOT IT'S JUST UP TO YOU TO TAKE YOUR TIME AND READ...