Skip to content

Vulcan Octave Fuzz

Based On
fOXX® Tone Machine
Effect Type
Octave Fuzz
Build Difficulty
Project Summary
A classic untamed fuzz from the 1970s that adds an octave-up overtone.
Vulcan Octave Fuzz printed circuit board

Printed Circuit Board

What's included?
PCB only. Build instructions and parts list can be viewed or downloaded from this page.


In stock

Complete Kit

Not yet available.
Kits are developed based on interest, so if you’d like to see one for this project, let us know.
Request Kit
51 people are interested.

Project overview

The Vulcan Octave Fuzz is a recreation of the fOXX Tone Machine, first released in 1971 and discontinued in 1978. The Tone Machine is a thick fuzz that uses a phase splitter and complementary rectifier to create an octave overtone.

The Tone Machine has a lot in common with the Fender Blender, but with a more pronounced octave and smoother tone, as well as the ability to disable the octave by turning off half of the phase splitter. And the tone is not unlike the Superfuzz, although it uses a different method of octave generation to get there.

The Vulcan is faithful to the original, but with two added modifications. First, the octave switch (normally just “on” or “off” in the original) now has a 3rd setting allowing you to bypass the series diode in non-octave mode. See build notes for more details on this.

The second modification is to the tone control. The tone control of the original is somewhat similar to the Big Muff, but many people find it’s difficult to get good sounds from the treble side of the rotation. By increasing the value of the treble-side tone capacitor, it improves the usability. A switch has been added to let you choose between two different capacitors in addition to the original.