Big Muff Pi
Two cascaded clipping stages and a tone stack that scoops the middle.
Two clipping stages, one after the other
Each stage rounds the peaks the gentle way, and running a second one into the first takes what is left of the slope with it. Two soft stages end up nearer a square wave than one hard one, which is why this reads as a wall rather than an edge.
- In
- Out
Drawn to illustrate the description above, not measured from a specific unit.
What the circuit does
Four transistor stages: an input buffer, two identical clipping stages with diodes in their feedback loops, then a tone stack and a recovery stage. The tone stack blends between a low-pass and a high-pass, so the middle of the control's travel takes the midrange out rather than leaving it flat.
What to listen for
Very long sustain and a wall-like thickness, with a hole in the middle of the frequency range. That hole is why it can sound enormous alone and then vanish underneath a band, and why players so often set the tone away from the centre.
Where it goes
The fuzz slot
Ahead of the other gain, and for some circuits ahead of everything. A vintage-style fuzz has a very low input impedance and is voiced around loading the guitar's pickups directly, so anything buffered in front of it changes what it hears.
Controls
- Volume
- Tone
- Sustain