Eurorack modules, and the notes from building them.
Arche Modular is a one-person shop in Indiana working on synthesizer modules — a chord generator, a suboctave divider, some utilities, and an oscillator that is still mostly a breadboard.
Everything gets written down: the circuits, the firmware, the bench setup, and the failures. Especially the failures, because those are the parts nobody publishes and everyone runs into.
Start here
Getting into Eurorack DIY means solving a pile of small physical problems before you ever design a circuit. How to power a breadboard at plus and minus twelve volts. How to lay out a panel in KiCad so the holes land in the right place. What an oscilloscope will quietly lie to you about. These are written from the bench, while doing the thing.
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Powering a breadboard at ±12 V
Battery packs, bench supplies, and what a module actually draws.
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Laying out a Eurorack panel in KiCad
Board outline, drill holes, and the HP grid — without leaving KiCad.
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What your cheap oscilloscope gets wrong
Narrow pulses, low duty cycles, and readings that are exactly double.
Modules
Three designs are far enough along to describe. Boards are in transit; none of this is for sale yet.
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Tonnetz
A chord generator built on neo-Riemannian transformations. Four pitch outputs, probabilistic voice leading under voltage control.
prototype — firmware
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Subspace
Suboctave generator and clock divider that works at audio rate and clock rate without changing its mind about which one it is.
boards in transit
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Buffered multiples
Two utilities. One buffered mult, and a dual version in the same width.
boards in transit
Build log
Dated entries, in order, including the parts that went wrong. A scheduler that died twenty seconds after boot every time. A crimp with two and a half ohms in it that starved a rail. A combination tone that walked downward through an octave sweep and took a week to explain.
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Read the log
Starting with the first fabricated boards and Knobcon 2026.