Fulltone 69

Happy #fuzzfriday, everybody! The 69 is Fulltone's take on the classic, late 60s, germanium Fuzz Face circuit. They've added a few extra controls to help shape the fuzz. The Bias (or Input as it's called in the 69 Mk II) pot is a common mod to the Fuzz Face circuit (it's a trimmer in the AnalogMan Sunface) and controls the input impedance. It can clean up the sound a little, just like rolling down the volume pot on the guitar. The Contour pot controls some of the voltage going to Q2 and the output cap. For more info, here's the schematic. Pots can be board mount from the solder-side of the circuit board and it should all fit in a 1590B just fine. The perf side of the drawing shows positive ground and the PCB side shows negative ground. Typical Fuzz Face germanium transistors should be used (Q1: hFE ~70, Q2: hFE ~100), but as always, socket and experiment.