The daddy of thick, meaty fuzz. Everyone needs some Muff in their life.
This circuit is the V4-5 (V5 was a V4 + tone bypass switch - you can make either). A 70's experiment in emulating the Big Muff Pi tone using op-amps rather than transistors resulted in this babe. It came kinda close, and in the process became its own sought-after sound. Similar territory to what you'd expect from a BMP, but with a heavy, grungy tone.
Check out the characteristic sound of it on Smashing Pumpkins' Siamese Dream
Pads included to make modifications suggested by AnalogGuru, which make it slightly crunchier, but it sounds great stock. Don't mess!
All this fuzzy fun fits into a 1590B enclosure. Fat muff in a skinny body. Sweet.
Optional tone-bypass switch is board-mounted for minimal wiring and easy enclosure mounting.
PCB size: 47 x 40mm