Boutique polyphonic synthesizer — play it live in your browser
The audio engine can't load over file://. Serve the docs folder with a local HTTP server:
python3 -m http.server 8080 --directory docs/
Then open localhost:8080
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Free download for macOS and Windows.
Native performance on Apple Silicon and Intel. Installer package.
VST3 · AU · Standalone
Optimised VST3 binary and Standalone application. Zip archive.
VST3 · Standalone
Professional-grade synthesis in a boutique package.
Band-limited waveforms with cross-modulation, hard sync, and per-voice detuning.
Zero-delay feedback state-variable filter. Self-oscillating. High resonance stability.
Independent envelope control on amp and filter. Shape your sound in time.
Route to pitch, filter, or amplitude. Configurable waveform and rate.
Configurable voice allocation and stealing. Unison and detune modes.
Every line of audio code verified against golden-master WAV files on every commit.
PolySynth runs on SEA_DSP — a bespoke real-time audio engine built from scratch. Lock-free, heap-free, and thread-safe in the audio path.
Every parameter change, every voice, every filter coefficient is verified against golden-master WAV files in headless CI. What you hear today is what ships.
View source on GitHub →Specifications
Unprocessed output from the synthesis engine. No reverb, no mastering.
Sawtooth Oscillator
Waveform Comparison
Oscillator Mix
Pulse Width Mod
Filter Sweep
Filter Resonance
Filter Envelope
LFO → Filter
LFO Vibrato
LFO Tremolo
Polyphonic Chords
Engine Polyphony
Factory Presets
Independent audio software. Made with care.
Side Effects Audio is a small independent studio building custom audio tools and effects. PolySynth is an ongoing project exploring high-quality polyphonic synthesis in software — designed to sound great, built to last, and verified at every commit.