Op Amp Big Muff Pi

The Op Amp Big Muff Pi re-creates the circuit of the op-amp Big Muff from around 1978. Instead of transistors and four gain stages, it uses op-amps and three gain stages, which gives a Big Muff sound with more crunch, suited to grungy wall-of-sound distortion, heavy rhythm playing and heavy leads.

Three knobs control the sound: Volume sets the output level, Sustain sets how much sustain and distortion is applied, and Tone sweeps from high treble to deep bass. A separate Tone switch takes the Tone control out of the circuit. A footswitch toggles between effect and bypass, and a status LED lights when the effect is on.

The pedal is analog and mono, with true bypass switching. It has a single input jack and an amp output jack, and sits in a compact die-cast enclosure. It runs from a supplied 9V battery, or from an optional 9.6VDC-200mA adapter that is sold separately.