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Proxima Optical Compressor

Based On
Flatline Compressor
Effect Type
Build Difficulty
Project Summary
A simple, cheap and surprisingly effective optical compressor that works great on bass or guitar.
Proxima Optical Compressor 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 Proxima Optical Compressor is an expanded adaptation of the Flatline Compressor, a DIY classic originally invented by John Hollis in 2001.

There have been several community modifications and revisions during the past two decades, so while the original version only had Sustain and Volume controls, the Proxima has a more deluxe control set.

This version includes several additions: a JFET input buffer to split the signal, a sensitivity or threshold knob, a clean blend by way of separate Effect Volume and Clean Volume controls, and an output buffer to correct the phase from the mixing stage. If you like the Flatline but wish it had more flexibility, the Proxima is what you’re after.

In addition to John Hollis, we are indebted to the work of Madbean and Stompville for many of the ideas utilized in this version, and we’re hopeful that ours will in turn inspire others to take it even further.