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Based On
Xotic AC/RC Booster
Effect Type
Build Difficulty
Malacandra printed circuit board

Printed Circuit Board

What's included?
PCB, build instructions, and parts list.


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.

Project overview

The Malacandra Boost / Overdrive is a recreation of the Xotic AC Booster and RC Booster, two nearly identical pedals that feature a two-band EQ for independent control of bass & treble frequencies. The result is a flexible tone machine that lets you go from a clean volume boost to a thick overdrive.

Looking at the schematic for the AC & RC Booster circuits, it’s very similar to a Tube Screamer, starting with an input buffer and an op-amp feedback diode clipping stage. The two major topological difference are that the AC/RC circuit uses an inverting op-amp stage for clipping (the TS is non-inverting), and the Tube Screamer tone control has been replaced by a Baxandall stage with bass and treble.

The BB Preamp (also available from Aion FX, called the Perelandra) is a similar circuit. The main difference is that it retains the Tube Screamer’s tone control section in between the clipping section and the Baxandall tone stack, hard-wired at the 9:00 position.

Version 2 of the Malacandra has been updated slightly based on direct traces of the current-production AC Booster and RC Booster as well as the Bass RC Booster. With the Malacandra PCB, you can build any of the three circuits by changing a few parts. Instructions are provided for each variant in the documentation.

Circuit history

The AC and RC Booster were released in September and November of 2002, respectively. “AC” is a reference to the Vox AC30 amplifier, and “RC” stands for “Rig Conductor”.[1] The BB Preamp, released a few years later in 2005, is a reference to the Marshall Bluesbreaker amp.

Notes & references

  1. A TGP user in 2015 says he emailed Xotic to clear this up and they confirmed the “Rig Conductor” name. However, I found several more references going back as early as 2005. So I think we can safely dispels the rumor that “RC” stands for “Really Clean” and “AC” stands for “Almost Clean”.

Documentation & Build Reports

Project Documents