Our friends at Gearphoria published a story about the legendary Fuzz pedal Arbiter Fuzz Face, one of the most cloned pedals in history. Here’s an excerpt:
“According to [gear journalist] RG Keen, the Fuzz Face circuit consists of two transistors, four resistors, three capacitors, and two controls.
Early Fuzz Face circuits employed several different types of germanium transistors. The AC128 and the NKT275 transistors found their way in, the former, which is reported to be a low quality transistor, and the latter, are very similar. However, in the hands of a good designer, with correctly tuned gain and frequency response, the little numbers on the tin can don’t matter.
Roger Mayer is reported to have tweaked Jimi’s gear to tailor it to his liking. Pedal designers took note and refer to the changes in the circuit as the Hendrix Mod or the Roger Mayer Mod. This modification appears to increase the output level and the gain of the second transistor, according to [Fulltone’s] Mike Fuller.” – Read the full article by Timothy Smith in the Summer 2017 issue of Gearphoria.
Jim Dunlop bought the rights of the Fuzz Face in 1993 and offers a stompbox faithful to the original in both design and aesthetic.
More info on how to build a Fuzz Face can be found here. Synthorek sells an Arbiter Fuzz Face clone kit.