One line in. A section out.
SXTN is the THIRI harmony engine pointed at a single melodic instrument. It hears the note you are playing, resolves the bar you are in, and answers with up to five correctly voiced parts built from your own signal — not a synth approximating it. Three ways to play it.
Standalone & VST
Runs on a Mac today. A standalone practice app where you type the changes and play over them, plus two VST3 builds for the session — one that harmonises your audio, one that emits the harmony as notes for any instrument to render.
- FormatsStandalone · VST3 · VST3 (MIDI)
- PlatformmacOS, builds from source
- StateWorking, unsigned
Elk Stomp
The pedal build. Five voices, chord intelligence and live pitch tracking inside a 1.333 ms callback on a stock $399 Elk Stomp, with no server and no network. First place at the Elk Audio Challenge, MUTEK Montreal.
- HardwareStock Elk Stomp
- Worst block1.11 ms of 1.333 ms
- StatePrototype, not for sale
KORUS
The voice. The same engine in a browser tab — sing a line and hear it answered in your own voice, formants intact. Nothing to install and no account.
- Runs inAny browser, a microphone
- ShifterPhase vocoder worklet
- StatePlayable now
WHAT BOTH RUN
The same decision, wherever it runs
Underneath both is one piece of code that takes a note, a chord and a key and returns the notes that belong with it. Integer arithmetic on fixed memory: no allocation, no waiting, no network. That is what makes it legal inside an audio callback, and what makes the pedal and the plugin agree.
- Golden vectors16,353 matched every build
- Voicingsclose, open, drop2, drop3, jazz
- Modes15, major through lydian dominant
- Charts16 slots, stored relative to the key