Tube boost + overdrive running off a 9 volt battery

[Pigyboy]

Ok, got the pictures figured out. Let me know what you think!

[Renegadrian]

Hey I like that! THX for posting...Nice wiring there...

[Pigyboy]

Thanks Adriano,
The only wire I had on had was from some heavy old electrical cabling I found. Quite colorful!  I notice I burned a few of them too. Going to try to simplify the layout a bit more next time. I think it is possible to eliminate 2 ground wires as the metal chassis itself links the input and output jacks to ground.

My friends from Germany, Mamasweed, and are here in Spain for some shows and the guitar player has used the Valvy for the last two shows and now he wants one. Using it live is the true testing ground and these little pedals really sound great.

[Stellan]

Hi, i have recently finished a modded valvecaster, and it sounds great but my volume pot is acting like a gain pot.
see the thread here:
http://www.diystompboxes.com/smfforum/index.php?topic=78671.0
Have anybody else experienced this with the valvecaster??

[frequencycentral]

Hi, i have recently finished a modded valvecaster, and it sounds great but my volume pot is acting like a gain pot.
see the thread here:
http://www.diystompboxes.com/smfforum/index.php?topic=78671.0
Have anybody else experienced this with the valvecaster??

Post up your voltages and we'll detect what's amiss.

Set the Gain, Tone and Volume to maximum. Hook up the black probe of your DMM to ground and use the red probe to take readings from each of the tube's 9 pins.

Here's mine, taken from my fully functional Valvecaster, my power supply is 12 volt:

Pin 1: 3.02v
Pin 2: -0.518v
Pin 3: 0.00v
Pin 4: 0.00v
Pin 5: 11.97v
Pin 6: 8.21v
Pin 7: -1.285v
Pin 8: 0.00v
Pin 9: 5.91v

Also, you have made some component changes - post what you have changed and any other modifications you have made to the circuit.

[Stellan]

Hi again,
Voltages usin 12v powersupply:
pin 1: 3,14
pin 2: -0,35
pin 3: 0,09
pin 4: 0,00
pin 5: 12, 04
pin 6: 7,45
pin 7: -0,52
pin 8: 0,11
pin 9: 5,86

Moddifications: C1 and C2 are both 22nf, and i have no tonecontrol wired up yet, but I don't see how that should cause problems... I tried other values for the other components but went back to stock values to see if that changed the problem. Obviously it did not.

[frequencycentral]

Hmm, your voltages look good to me. It should be working fine.

Do you still have a pot at the input? Is the gain control now standard?

[Stellan]

Do you still have a pot at the input? Is the gain control now standard?

Thanks for the replys.
I took the gain pot out of the circuit and jumpered the cathode to ground. I also tried different values for the catode resistor, all with the same result.
I have checked all connections with the DMM and everything seems fine to me. Really frustrating, as this should be fairly easy. There must be something
that I am missing...

[frequencycentral]

I took the gain pot out of the circuit and jumpered the cathode to ground.

With the cathode grounded the overdrive will be 'always on'. The lower the resistance between the cathode and ground, the more overdrive you will get. You have hardwired it for maximum overdrive. Put that gain pot between the cathode and ground, I prefer a value of 100K, as that way you can have cleaner boost than with 50K

[Stellan]

Yeah, I'll do that as soon as I have got this volume issue sorted out. I hardwired it for max gain, so it would be easy to hear if the volume could be turned down without turning down the gain.

[Pigyboy]

Hi,
Just finished a hybrid of the twincaster/pepper shredder. Sounds great but I am getting a bit too much sizzle as the note fades. Any idea where I should look?

Thanks

[frequencycentral]

Sizzle?

Schematic?

[Pigyboy]

I used the Pepper Shredder Schematic at
http://www.tube-town.net/diy/lov/lov02-peppershredder-eng.html
but substituted the 1MA gain for  50kB and the volume 50kA for a 100kA. When I used the 1M for the gain and the 50k for the volume I got real bad sizzle. I also changed C5 and C8 from 10K to 22K resistors and it seemed to smooth it out a bit.
I used the tone stack from the twincaster schematic on this thread. Basically a .01uf cap in series with a 100kA pot. I like the crunch of the sound but it does get a small sizzle sound if I let a note ring and fade. It is almost a clipping sound. I have a good power supply that works well with my other pedals so I do not think it is the problem. Thanks for the help.

[Ripthorn]

Are you saying you took the pot for gain out of the pepper shredder and put in the variable cathode resistor gain control of the valvcaster?  If you simply replaced the value of the pot, that isn't going to result in the best sound.  If you did put the gain control on the cathode, did you remove the cathode resistor?  Also, if you change the cathod bypass caps, you can control how much low end is let through.  If you then put a resistor in series with that bypass cap, you can tame the high end gain and get (what I think) is a little smoother of a response.

[Pigyboy]

Hi,
I used the pepper shredder schematic so the gain is between stage one and two of the first tube and not off the cathode, right?
Do you recommend I use the exact parts called for in the pepper shredder schematic? I have not heard the pepper shredder before this so I have nothing to judge the sound by and breadboarded it was very trebly. I am just learning about this stuff so thanks for bearing with me and my mistakes.

[Ripthorn]

Tube preamps when used direct can sound insanely harsh and fizzy.  If you are playing through a speaker, a lot of that will go away, though possibly not all of it.  Also, having changed the gain pot, there will be less gain available, as the signal will bleed to ground earlier with a 50k pot than with a 1M pot.  If you are needing to get rid of some highs, I would look at putting a resistor in series with cathode bypass cap, or put in a set low-pass filter at the output just before the volume pot to get rid of some of that.  You can experiment with both or a either and find what works best for you.  To start, maybe try a 1k5 resistor in series with the first cathode bypass cap and see what that does.

[Pigyboy]

Thanks for the help. I will give it a try and post my results.

[T-200]

Hi you all,
I just joined this forum and I'm very glad to see that there are lots of people helping each other to save money with these gadgets.
I am going to build one of these boxes to my son for his guitar rig, but I wonder if I could modify it to make another one for my Hammond organ.
It's a T-200 solid state organ which I have modified heavily and it sounds pretty good with passive zener diode overdrive. I just would like to try if the tubes could add a little warmth to the sound. I've tried some regular overdrives inserted after the pre-amp (~600mV) but they won't sound good, there's too much noise.
I thought I could try this as it is first, but if someone has an opinion or a suggestion I will be more than happy 

Thanks,
Jussi from Finland

[Ripthorn]

You won't be saving money in the long run, believe me, I have spent way more on this than I would have spent on pedals.  Of course, I have a lot more pedals than I would have had.  The only way to really answer your question is "try it out and see what happens".  As for noise, you might not see a significant improvement over a solid state circuit.

[T-200]

Thanks for your answer.

I think I didn't make myself clear, sorry for my lousy English...
The question is: Can this effect handle line level input signals as it is, or do I have to change some components? And is the output level strong enough to match the line level input of the main amp, or does it need any modification?

I know that the problem with the ordinary pedals in this case is that in most guitar pedals there's a bass roll-of circuit to make the sound sharper, and that is not what I want. Also the output signal isn't usually strong enough without a buffer amp, and that's what causes the noise when using them with line level signals.

I guess I just have to build the guitar version first and try it with the organ. I was just hoping that someone would have had the same problem and already solved it...

Cheers,
Juha