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Tachyon Amp Overdrive

Based On
Effect Type
Overdrive / Distortion
Build Difficulty
Project Summary
This heavy overdrive is a hidden gem in the pantheon of BOSS pedals, offering creamy lead tones and biting rhythm in an easy-to-use package that is surprisingly complex under the hood.
Tachyon Amp Overdrive 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

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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 Tachyon Amp Overdrive is a recreation of the “Lead” mode of the BOSS® SD-2 Dual Overdrive, originally sold from 1993 to 1998.

The SD-2 is interesting in that it’s two fully separate pedals in one box. The “Crunch” and “Lead” modes each use dual-concentric potentiometers allowing for separate settings for Gain, Tone and Volume. The mode can be changed via either a rotary switch selector, the on-board footswitch in A-B mode, or a remote switch.

Unfortunately for BOSS, the Crunch mode was pretty weak and brittle-sounding, and so the pedal was largely ignored. However, the Lead mode really shines. It’s one of BOSS’s best drive effects—while also being one of the most obscure, since it’s buried inside a pedal that was otherwise overlooked.

Despite only having three very basic controls, the SD-2 has a lot going on under the hood. It’s very linear, using five distinct op-amp stages for setting the gain, clipping the signal and shaping the EQ—a similar approach taken by Friedman for the BE-OD and Dirty Shirley pedals, or by the Amptweaker Tight Metal.