Keeley Fuzz Head

Over a decade ago Robert Keeley was kind enough to share this design with the DIY community. It's a fairly unique fuzz, with a germanium treble booster at the beginning, a differential amplifier in the middle, and a basic buffer at the output (this is so it will play nice with other effects). Robert's full explanation of the circuit can be found here, however note that the schematic in that document isn't what I used. I used this later one with a tone control, and ended up laying it out with all controls externally. The PreGain control originally was a trimmer because it has a tendency to crackle when turned, but for ultimate tweak-ability I moved it externally.