A dual-voice bytebeat synthesizer for Eurorack.

Ogham turns tiny mathematical formulas into music. Instead of oscillators and wavetables it runs bytebeat expressions - single lines of integer arithmetic that, evaluated over time, produce surprisingly rich rhythmic and melodic patterns. It is pretty chaotic and noisy, though there are many sweet-spots to discover.

Ogham hosts a bank of 100 of these formulas, plays two of them at once, shapes them with a bipolar Tone macro and a three-stage modulation chain, and clocks, pitches and modulates them from the rest of your system.

Watch the quick-start video → https://www.youtube.com/watch?v=7hTkgFIJPIU

At a glance:

100 function slots (F0-F99), each with two performable parameters, plus a built-in A=440 Hz tuning reference. All hundred are filled, grouped by character: twenty each of textural, noise, percussive, rhythmic and melodic.

Two independent voices - Out 1 and Out 2, each playing its own function over a shared time base.

Drone / freeze - decouple Out 2 into a self-sustaining voice that ignores the knobs, clock, pitch and FX, and solo over it on Out 1.

Bipolar Tone macro - one knob from clean through low-pass filtering and wavefolding one way, sample-rate reduction and resonant band-pass grit the other.

Three-stage modulation FX - Chorus → Flanger → Phaser, each with a clean and a characterful variant, in series or parallel.

Clk ↔ V/oct on a shared jack - external tempo (one pulse per beat), or 1 V/oct driving the playback rate, so a formula’s own pulse tracks the CV across ~5 octaves.

Hard-sync input - sample-accurate waveform reset, usable up to audio rates.

Internal low-pass gate - plucked from the Sync input, with the filter and VCA moving together for a struck, percussive character. Decay from 2 ms to 20 s; drive it from a trigger sequencer and Ogham plays notes.

CV over both parameters (±5 V, summed with the knobs); either can be re-routed to sweep the Tone macro instead.

Selectable CV output - an envelope follower of either voice, or a raw bytebeat used as a slow DC modulation source, plus an end-of-cycle pulse.

Everything in the menu persists across power cycles, with a one-gesture factory reset.

Available in VCV Rack 2

https://keeos.io/modules/ogham/