Tone Bender MK II questions

[soggybag]

I got some of these PCBs from OSH Park (this is a great service)

https://oshpark.com/shared_projects/e4OCWa0X

Follows the Schematic from http://fuzzcentral.ssguitar.com/mkII.php

It adds a third pot, 25k, in place of the 8k2 resistor on the collector on Q3. Seems like a good place for a trim pot.

Has anyone else used a pot here before I'm curious how useful this is? Of course I just build one and listen. I just thought I'd get options first.

[Electric Warrior]

Which schematic? Only the first one with the OC81Ds is entirely correct.

They had different resistor setups for OC81Ds and OC75s. The latter always had a 10k on Q1's base and a 47k on Q2's collector. That's where you would put the trim pots -  if you really need them. Q2 sets the bias for Q3. When it's collector voltage is set correctly, Q3's voltage will be good as well.

The 100k/100k setup works for low leakage types, 10k/47k needs more leakage.

[soggybag]

This is a knob on the box adjusting a 25k replacing the 8k2 resistor at the collector of Q3. At first glance I'd think you'd want this to be a trimmer and leave it. This board is implying this is a useful control to adjust the sound.

[Gus]

IMO you were given a better place to adjust the circuit.

Try adjusting the the 2nd stage like Electric Warrior posted.

I am surprised alter all the years forums about effects have existed the adjust the last stage collector value on a FF like or MK 2 etc still has people suggesting it.