supersynth

High-performance audio synthesis for Node.js, Bun, and Deno — backed by native Rust bindings via CPAL.

• 12 waveforms — sine, square, sawtooth, triangle, principal, trumpet, flute, pulse, noise, plucked, struck, electric
• Expressive oscillators — exponential ADSR, pitch/amplitude LFOs, chiff pipe-attack transients
• Organ engine — stops, presets, mixture ranks, drawbar control, key-click
• Effects — Freeverb reverb, overdrive, Leslie rotary speaker, limiter
• MIDI input — hardware device support via midir
• Multi-backend — CoreAudio, WASAPI, ALSA, PulseAudio, PipeWire, JACK
• Offline rendering — generate audio without hardware for testing and file export
• TypeScript-first — full type definitions throughout

Status

The organ engine is the current focus of active development and is the most polished part of the library. The baroque pipe organ simulation — including the principal waveform, mixture ranks, breaking stops, drawbar control, key-click, and Leslie rotary speaker — is production-quality.

All other instrument classes (Piano, Guitar, Flute, Trumpet, etc.) are works in progress. They produce sound and are usable, but their voices have not been tuned to the same standard. Expect rough edges.

Install

npm install supersynth

Prerequisites: Rust and Cargo must be installed to build the native addon. Install from rustup.rs.

Quick start

import { Synth } from 'supersynth';

// Play a note through your speakers
const synth = new Synth({ masterVolume: 0.5 });
await synth.start();

synth.noteOn(69, 100);                          // A4, velocity 100
await new Promise(r => setTimeout(r, 2000));
synth.noteOff(69);
synth.stop();

Use a pre-built instrument class for a specific sound:

import { Organ, Piano, Flute } from 'supersynth';

const organ = new Organ({ masterVolume: 0.7 });
await organ.start();
organ.activatePreset('principal');
organ.noteOn(60, 100).noteOn(64, 100).noteOn(67, 100); // C major chord

Configure voice directly for custom synthesis:

import { Synth } from 'supersynth';

const synth = new Synth({
  voice: {
    oscillators: [{ waveform: 'sawtooth', attackTime: 0.1, releaseTime: 0.4 }],
  },
  reverb: { roomSize: 0.8, wet: 0.3 },
  masterVolume: 0.6,
});

Documentation

| Topic | Description | |-------|-------------| | Synth | Core class — constructor, methods, events | | Voice & Oscillators | VoiceConfig, OscillatorTemplate, VelocityCurve | | Waveforms | All 12 waveforms with parameters and implementation notes | | Instruments | 20 pre-built instrument classes | | Organ | Organ engine — stops, presets, drawbars, mixture ranks | | Effects | Reverb, overdrive, Leslie, limiter | | MIDI | Hardware input, events, raw MIDI bytes | | Errors | Error classes and handling |

Examples

npm run example:tone    # 440 Hz sine for 2 seconds
npm run example:chord   # C major chord with reverb
npm run example:midi    # Bach BWV 532 MIDI file through organ

Play any MIDI file:

node --import tsx examples/midi-file.ts /path/to/your.mid

See the examples/ directory for 20+ instrument demonstrations.

Benchmarks

npm run bench           # throughput vs node-web-audio-api and web-audio-api
npm run bench:realtime  # real-time callback timing under GC pressure

Why native Rust?

• Real-time reliability — the CPAL audio thread runs outside Node's event loop, never paused by V8's garbage collector
• JACK support — direct low-latency connection to JACK audio graph for professional Linux setups
• Synthesis features — mixture ranks, Freeverb, Leslie rotary, and Karplus-Strong have no equivalent in standard Web Audio API node graphs

Tests

npm test            # TypeScript integration tests (no hardware required)
npm run test:rust   # Rust unit tests

Building from source

git clone https://github.com/jddubois/supersynth
cd supersynth
npm install
npm run build
npm test

Architecture

TypeScript API (src/)
      ↓  napi-rs bindings
Rust synthesis engine (native/src/)
  ├── synth/     oscillators, envelopes, LFOs, chiff, waveforms, Karplus-Strong
  ├── effects/   Freeverb reverb, overdrive, biquad, low-pass, limiter, Leslie
  ├── midi/      MIDI parsing, device input (midir)
  └── audio/     CPAL backend selection and stream management
      ↓  CPAL
CoreAudio / WASAPI / ALSA / PulseAudio / PipeWire / JACK

License

MIT