First of all, please excuse my poor english since it is not my mother language.
I have made my own Fuzz Face with a 250K pot for the "fuzz" pot instead of a 1K pot (because of a wrong schematic). So it reacts strangely: with the pot turned full up, the sound seems good to me, very fuzzy, while when I decrease the pot a little bit, the sound is much cleaner and it seems to cut the high frequencies.
Since I don't have a 1K pot by my hands, I tried with a 500 ohms pot, and the sound is just clean (no fuzz) when it is full up, while I have no sound at all when the pot is turned full down. With 10K and 20K pot, the sound is fuzzy but with a "noise gate" effect!
So I wonder:
1. Could we use a pot significantly different from the 1K one (for example 10K or 250K), or the 1K value is just optimised (we just can go up to 2K pot)?
2. Is there any interaction between the volume pot and the "fuzz" one (for example do we have to turn up the volume pot while we turn down the "fuzz" one to compensate a loss of volume)?
start with a 2k2, and a parallel 5k [5k wiper and outside lug connected to the 2k2's outside lugs]...turn the 2k2 all the way up, adjust the 5k to what you want as max fuzz [maybe a touch more] measure the resistance setting of the 5k [don't disturb the potshaft between setting it and measureing it out of circuit]then replace the 5k pots set resistance with a fixed resistor.
Just as well really [since we 'never' use FF's at very low gain settings] ...add a 1k [or so] resistor between your 500ohm pot and ground, this will range between 500ohm and 1k5, sure to hit your gain setting choice.
There is resistance variable with the gain pot between the 22uf, ground and the feedback loop, I'm not certain but...technique 1 [starting with a larger than necessary 2k2 fuzzpot and trimming it] seems to bear out into pedalboard applications for me, I think there may be something to having that gain sections fixed resistance [the pot wafer and any series resistance] set so that max gain uses the pot near full on. IOW if a larger than necessary pot [or pot + seriesed stop resistor] is used and turned down some, there is still the wafers set resistance between ground and feedback loop...this is more of an observation/question...like I say it seems to bear out in 'usage'...I A/B FF circuits, may the best FF win pedalboard/box use...[not sure how or if it really matters, YMMV, some may like the sound of a high gain with the Fuzzpot turned down [more resistance between Gnd And FB loop.