PEDAL BENCH
by Stompbox Labs
← All pedals
Fuzz1995· Z.Vex Effects (USA)

Z.Vex Fuzz Factory

Five-knob germanium madness — gated splat, oscillation, and Velcro fuzz on demand.

⏳
Schematic pending verification

We don't ship reference schematics until they've been hand-authored against authoritative sources (manufacturer service docs, ElectroSmash analyses, GEOFEX writeups) and reviewed in the simulator. Until then, the BOM, signal chain, controls and mod notes below are accurate, and you can still add this pedal to a project — it just won't include a circuit yet.

About

A two-stage germanium fuzz (NKT275) with knobs that expose bias, gate, and feedback parameters normally fixed in a Fuzz Face. The result is wildly interactive: misbias the circuit on purpose to get gated splatter, self-oscillation, octave-down ghosting, or smooth vintage fuzz.

Signal chain preview

5 stages
Input
Q1 PNP germanium gain stage (Drive controls bias)
Q2 PNP germanium gain stage (Stab controls collector voltage)
Comp pot in feedback loop (changes input impedance and compression)
Gate pot (noise gate / threshold)
Volume pot and PNP-friendly positive-ground power
Output

Quick facts

  • Matt Bellamy (Muse) hardwired one into his guitars and the pedal became a Muse signature sound.
  • The five controls are: Volume, Gate, Comp, Drive, Stab — Stab biases the second transistor, so it is highly temperature dependent.
  • Z.Vex hand-paints every original in his Minneapolis shop; the Vexter line is a lower-cost screen-printed version.

Controls

  • Volume
  • Gate
  • Comp
  • Drive
  • Stab

Mod recipes Pro

3 mods
  • Silicon Q2

    Stabilize the bias against temperature drift.

    How: Swap Q2 (germanium) for a BC108 / 2N3904 silicon. Re-tune Stab pot range with a series 4.7k for a usable sweep.

  • Bias indicator LED

    Visual cue when the circuit enters self-oscillation.

    How: Tap Q2's collector through a 1M resistor + 10nF cap into a high-gain comparator (LM393) driving an LED.

  • Charge-pump positive ground

    Run the pedal alongside negative-ground pedals on a shared supply.

    How: Add a MAX1044 charge pump to invert the 9V supply internally — keep the rest of the circuit positive-ground.

References