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Based On
Runoffgroove Supreaux
Effect Type
JFET Overdrive
Build Difficulty
Project Summary
An adaptation of the Supro 16T amplifier, with JFETs replacing the tube stages.
Supreaux 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.
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Project overview

The Runoffgroove Supreaux is an adaptation of the Supro 16T amplifier, originally designed in 2004. While it was later revamped in 2008 as the Supreaux Deux, designed to be more accurate to the sound of the Supro amp, the original version is notable for being the source for the JHS Superbolt, one of their most popular pedals.

The JHS Superbolt, first released in 2012, changed a couple of values to bias the JFETs for 18V operation, as well as adding an on-board charge pump for 18V operation from a 9V supply. A toggle switch was also added to switch between “hi gain” and “low gain” modes.

The second version of the Superbolt from 2016 changed the “Hi/Lo” toggle into a switchable gain boost. It’s not been traced, but from their description, it appears to be a separate boost stage that goes before the main circuit to push it into overdrive more easily.

The Aion FX version of the Supreaux incorporates the JHS mods from the first version of the Superbolt, including the 18V charge pump, and it is more accurate to call it a clone of the Superbolt than the Supreaux. If you want to build the original Supreaux circuit, check the build notes later on for details.

Since the J201 is very difficult to find in TO-92 through-hole format, and many DIY hobbyists are intimidated by SMD parts, Aion FX offers J201s in SMD format that have been pre-soldered to adapters so they can be used as through-hole parts.