Here is a strange Germanium fuzz from yesteryear. There is a layout for this on tagboardeffects.com. That layout has an error that is corrected in the comments: C3 should be 47nF, not 47uF as shown on the layout. The original schematic is barely legible, so I redrew it. The ATTACK control varies the gain a little, but to me it's more of a timbre control. It's not entirely clear which end should be clockwise. The only way to roll-back the gain substantially is with the guitar's volume. The tone of this fuzz is sort of similar to the FZ-1. It has a crazy footswitch arrangement that interrupts the power when in bypass. I have no plans to try the switch, but I expect it will pop and it is definitely not true bypass.
Took me a little while to figure out how this thing works, what with all of the connections to Q2's emitter. Turns out that point has very little signal and basically acts like a 1.1V power supply for the 1st & 3rd stages. It does sag a bit when played hard, which adds to the character of the tone. Q1 and Q3 are leakage-biased, which means transistor selection has a major effect on circuit operation and tone. I breadboarded an NPN version using MP38As because they are fairly leaky. I tried varying a few things and the only change that stuck so far was increasing the VOLUME control to A100K. If we use true-bypass switching, then R10 is unnecessary. C3 is critical. Without it, the circuit has a tendency to oscillate (don't ask me how I know this). The tone can be fattened up by increasing C1, C5 and/or C6, although it sounds pretty good with stock values. R9 can be varied to dial-in Q3's bias. I think this fuzz would benefit from a Treble-cut control at the output.
Took me a little while to figure out how this thing works, what with all of the connections to Q2's emitter. Turns out that point has very little signal and basically acts like a 1.1V power supply for the 1st & 3rd stages. It does sag a bit when played hard, which adds to the character of the tone. Q1 and Q3 are leakage-biased, which means transistor selection has a major effect on circuit operation and tone. I breadboarded an NPN version using MP38As because they are fairly leaky. I tried varying a few things and the only change that stuck so far was increasing the VOLUME control to A100K. If we use true-bypass switching, then R10 is unnecessary. C3 is critical. Without it, the circuit has a tendency to oscillate (don't ask me how I know this). The tone can be fattened up by increasing C1, C5 and/or C6, although it sounds pretty good with stock values. R9 can be varied to dial-in Q3's bias. I think this fuzz would benefit from a Treble-cut control at the output.
