Univox Super-Fuzz

Another vintage fuzz box, used by Pete Townshend of The Who. From the wiki:

There are two unique features of this device that set it apart from other distortion and fuzz pedals. The first is that the full-wave rectification of the circuit produces an upper octave as well as a slight lower octave. This also gives the sound a lot of compression and gives a mild ring modulator effect. The second unique feature is a tone switch that engages a 1khz filter that "scoops" the mids, giving a very fat, almost bassy tone, unique to this circuit.