Two Sticks of Derm Fuzz gain control

HamishR

Well-known member
I searched this because I was sure this had come up before - is there a way of turning this fuzz into a 2-knob pedal with gain and volume knobs? Or is it not worth the trouble?

Thanks!
 
Good thought, but R4 and R8 are already being bypassed by C3 and C6. So you could introduce a pot between C3 and ground, or C6, or both.

Or put like a volume pot on the input, not sure if that would work well with this circuit.
 
One option:
Pull R5 and C5.
Use a continuity tester to figure out which R5 pad connects to C4, and which connects to ground.
Connect Lug 3 of a 100K pot to C4 via the appropriate R5 pad.
Connect Lug 1 of the pot to ground via the other R5 pad.
Use a continuity tester to figure out which C5 pad connects to R5 and which connects to Q2-base/etc.
Connect Lug 2 of the pot to one side of a 100n cap
Connect the other side of the 100n cap to Q2-base/etc via the appropriate C5 pad.

This should give you a gain control between the two stages.

Another (easier?) option would be to just add a pot between the footswitch and the PCB.
Lug 3 to the footswitch
Lug 1 to ground
Lug 2 to the PCB

You might have to try a few different values in case there's any weird loading or anything happening, or you might want to add a treble bypass cap between lugs 2 and 3 to retain a bit more high end as you roll back the gain.
 
Following here for ideas. I had purchased a pre-drilled 1590b for another one-knob project that also included an additional hole on the face for a spdt/dpdt. That idea sort of fizzled, so picked up a TSoDF pcb to build out a doom-y type fuzz.

But what to do with that other spot? Any good suggestions for cap changes that would maybe increase or cut bass frequencies? Or do something else that might be cool? I'm still in the "paint by numbers" stage of pedal assembly, and I've only colored outside the lines in a few instances. Super appreciative of any interesting options!
 
Following here for ideas. I had purchased a pre-drilled 1590b for another one-knob project that also included an additional hole on the face for a spdt/dpdt. That idea sort of fizzled, so picked up a TSoDF pcb to build out a doom-y type fuzz.

But what to do with that other spot? Any good suggestions for cap changes that would maybe increase or cut bass frequencies? Or do something else that might be cool? I'm still in the "paint by numbers" stage of pedal assembly, and I've only colored outside the lines in a few instances. Super appreciative of any interesting options!
For bass modification, C1, C5 and C7 all filter bass.
You could double C5 and C7 to 200/220n then switch C1 for more/less filtering at the input.
Or do a filter cap pot where you blend between 2 filter caps with a low value linear pot. If you try that, experiment on the breadboard. Try values that are at least 10x each other, 47n and 470n or even more 20n and 1u.
I'm toying with this on a muff build but wasn't happy with my values and haven't circled back to it. You need to exaggerate the values as they'll always be in some amount of parallel.
Switching is much simpler. Or even a rotary.
Here's one of many threads on input cap blending

Some over at madbean as well


Good luck!
 
One option:
Pull R5 and C5.
Use a continuity tester to figure out which R5 pad connects to C4, and which connects to ground.
Connect Lug 3 of a 100K pot to C4 via the appropriate R5 pad.
Connect Lug 1 of the pot to ground via the other R5 pad.
Use a continuity tester to figure out which C5 pad connects to R5 and which connects to Q2-base/etc.
Connect Lug 2 of the pot to one side of a 100n cap
Connect the other side of the 100n cap to Q2-base/etc via the appropriate C5 pad.

This should give you a gain control between the two stages.
I may be envisioning this wrong but wouldn't this also alter the CR filter made by C4 R5?
 
For bass modification, C1, C5 and C7 all filter bass.
You could double C5 and C7 to 200/220n then switch C1 for more/less filtering at the input.
Or do a filter cap pot where you blend between 2 filter caps with a low value linear pot. If you try that, experiment on the breadboard. Try values that are at least 10x each other, 47n and 470n or even more 20n and 1u.
I'm toying with this on a muff build but wasn't happy with my values and haven't circled back to it. You need to exaggerate the values as they'll always be in some amount of parallel.
Switching is much simpler. Or even a rotary.
Here's one of many threads on input cap blending

Some over at madbean as well


Good luck!
Thanks again! I'll have at this once my next parts order arrives... forgot I'm all out of 1/4" jacks... d'oh
 
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