The Multivox Big Jam Distortion is a distortion pedal first released in 1978. Multivox commissioned Firstman Electronics, also known as Hillwood, to manufacture it, and it became one of the key successes of the Big Jam pedal series1. It belongs to the broader family of distortion pedals.
What it does
The Big Jam Distortion is an American 1970s era hard-clipper distortion, a circuit approach it shares with pedals such as the early MXR Distortion+ and DOD 250, though it sits adjacent to those designs rather than being identical to them1. A hard-clipper works by sharply squaring off the guitar signal's peaks, which is what produces the pedal's distortion character.
Controls and circuit
Where most pedals of its day used rotary knobs, the original Big Jam Distortion used slider controls, set into a very distinct 1970s era appropriate enclosure1.
The circuit is built around a UA741/LM741 op-amp, 1N60 germanium diodes, and two C945 silicon transistors1.
The original 1978 pedal is long out of production. The Big Jam Distortion was one of the key successes of the Big Jam pedal series1.
What reviewers said
The Big Jam Distortion has been described as one of the key successes of the Big Jam pedal series1. It arrived in 1978, built around a UA741/LM741 OpAmp, 1N60 Germanium Diodes and two C945 Silicon Transistors1.
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Sources (1)
- Guitar Pedal X, Guitar Pedal X, 2026-03-26