Corvus

Aion FX from Des Moines, IA has helped guitarists build studio-quality effects since 2011. They document rare Big Muff variants that most players never knew existed.

The Corvus recreates the 1977-1980 op-amp Big Muff Pi, a complete redesign by Howard Davis and Michael Abrams. Unlike the famous 4-transistor circuit, this version uses op-amps exclusively - the circuit bears no resemblance to earlier Muffs apart from the tone control. The 1978 revision added a Tone Bypass switch for more aggressive, raw fuzz.

This variant remains one of the rarest Big Muff iterations. While the sound concept stayed similar to transistor versions, the op-amp architecture delivers different harmonic character and compression behavior. The Aion version makes this obscure variant accessible to builders curious about EHX's experimental period.