Introduced in the mid-late 1970s, the Big Muff Pi V4 features one less gain stage and Op-Amp chip circuitry, but is housed in the same classic enclosure as its predecessor, the V3. Though it isn't based around the classic four-stage Muff circuit, it has a unique, metallic sound that is great for heavily distorted playing. The Big Muff Pi V4 features the usual volume, tone and sustain controls.