Interfax - Harmonic Percolator HP-1

FUZZ

The Harmonic Percolator is a distortion pedal that was made in Milwaukee, Wisconsin in the 1970's. It used a silicon and a germanium transistor in a design that passes even order harmonics while suppressing odd order harmonics. These even order harmonics are more pleasing to the ear than odd order harmonics. The Harmonic Percolator also responds well with multiple notes.

The left slider is the input gain or distortion control and the right one is the output control. The input is on the left and the output is to the right when looking down on it. This is opposite pedals of today but in its time this made sense. Left to Right - the same way you read.

http://www.theremaniacs.com/percolator.html