chord-synth

Generate chord progression WAV files. Zero dependencies. Node.js only.

28 named presets, 22 arpeggio patterns, 7 instruments, slash chords (Am/E), transposition, pad/bass/drum tracks, reverb.

Quick Start

# Install globally
npm install -g chord-synth

# Generate a WAV file
chord-synth --preset "C G Am F" --bpm 120 --output pop.wav

# Custom jazz with slash chords
chord-synth --preset "Dm9 | G7/B | Cmaj7 | Am7/E" --instrument piano --drums bossanova --output jazz.wav

# Named preset transposed to key of G
chord-synth --preset "I-V-vi-IV (Pop)" --transpose 7 --output pop_in_G.wav

# Batch render from JSON file
chord-synth --batch render_jobs.json --output ./wavs/

Use as MCP Server

Exposes generate_wav and list_options tools to any MCP-compatible agent (Claude Desktop, Claude Code, Cursor, Windsurf, etc).

Claude Desktop — add to claude_desktop_config.json:

{
  "mcpServers": {
    "chord-synth": {
      "command": "npx",
      "args": ["-y", "chord-synth", "mcp"]
    }
  }
}

Claude Code:

# Add to Claude Code (point to the installed mcp-server.js)
claude mcp add chord-synth -- npx chord-synth --mcp

Then ask Claude: "Generate a sad violin arpeggio over Am F C G at 80 BPM" — it will call generate_wav directly.

ChatGPT Codex:

Prompt:
I have a mcp tool to generate chord wav files at https://github.com/Misfits-Rebels-Outcasts/chord-synth,
use it generate a chord progression for violin "Am Dm G C" at 128 bpm 

Use as Node.js Module

const { renderJob, PRESETS, SCHEMA } = require('chord-synth');
const fs = require('fs');

// Render a WAV buffer
const wav = renderJob({
  preset: "C G Am/E F",
  bpm: 120,
  instrument: "piano",
  pattern: 1,        // Up
  enablePad: true,
  drumPattern: "poprock"
});

fs.writeFileSync('output.wav', wav);

Agent Interface

Agents should call chord-synth --schema to get the full JSON tool specification:

chord-synth --schema

Returns:

{
  "tool": "chord-synth",
  "description": "Generate chord progression WAV files...",
  "input_schema": {
    "type": "object",
    "required": ["preset"],
    "properties": {
      "preset": { "type": "string", "description": "Named preset or custom chords..." },
      "bpm": { "type": "integer", "default": 120 },
      "instrument": { "type": "string", "enum": ["piano","guitar","violin",...] },
      ...
    }
  },
  "examples": [...]
}

List all available options:

chord-synth --list

Parameters

Parameter	Type	Default	Description
preset	string	required	Named preset ("I-V-vi-IV (Pop)") or custom chords ("C G Am/E F")
bpm	int	120	Tempo
transpose	int	0	Semitones (-11 to +11)
pattern	int	1	Arp pattern index (see below)
rate	string	"1/8"	Note rate: 1/1 1/2 1/4 1/8 1/16 1/32 (add T for triplet)
instrument	string	"piano"	piano guitar violin flute clarinet cello bass
octaveRange	int	1	1-4 octave span
baseOctave	int	3	Starting MIDI octave
velocity	int	90	MIDI velocity 1-127
swing	float	0.5	0.5=straight, 0.66=medium, 0.75=heavy
loops	int	2	Progression repetitions
enablePad	bool	true	Sustained pad chord track
padOctave	int	4	Pad voicing octave
padVolume	float	0.12	Pad volume (0.0-0.3)
enableBass	bool	true	Auto bass (slash chords set bass note)
enableDrums	bool	true	Drum track
drumPattern	string	"poprock"	See drum patterns below
reverbMix	float	0.18	Reverb amount (0.0-0.5)

Named Presets

Category	Presets
Pop/Rock	I-V-vi-IV (Pop), I-vi-IV-V (50s), vi-IV-I-V (Sad), I-IV-V-IV (Rock), I-V-vi-iii-IV (Canon)
Jazz	ii-V-I (Jazz), I-vi-ii-V (Jazz Turnaround), iii-vi-ii-V (Coltrane), Autumn Leaves, So What, Steely Dan
Neo-Soul/R&B	Neo-Soul I, Neo-Soul II, R&B Smooth
Blues	12-Bar Blues, Minor Blues
Latin	Bossa Nova, Girl from Ipanema, Andalusian Cadence, Royal Road (JP)
Modal/Ambient	Dorian Vamp, Lydian Float, Ambient Pads
EDM	EDM Anthem, Trance, House
Classic	Pachelbel Canon, Gospel

Or use any custom chord string: "Fmaj7 Em7 Dm9 Cmaj7", "Am | Dm/F | E7 | Am", etc.

Arp Patterns

Index	Name	Index	Name
0	Chord (Block)	11	Pinky-Thumb
1	Up	12	Thumb-Pinky
2	Down	13	1-3-5-3
3	Up-Down	14	1-5-3-5
4	Down-Up	15	1-5-8-5
5	Up-Down (No Repeat)	16	1-3-5-8-5-3
6	Down-Up (No Repeat)	17	Alberti Bass
7	Random	18	Stride
8	Random Walk	19	Broken 3rds
9	Outside-In	20	Pedal Tone
10	Inside-Out	21	Alternating Bass

Drum Patterns

8beat 16beat poprock acousticpop bossanova swing funk rnb waltz arpeggio none

Chord Notation

Roots: C C# Db D D# Eb E F F# Gb G G# Ab A A# Bb B

Qualities: (major) m 7 maj7 m7 dim aug sus2 sus4 9 m9 maj9 11 m11 13 6 m6 dim7 m7b5 add9 5 power

Slash chords: Am/E (Am chord, E bass note), C/G, Dm7/A

Separator: spaces or | both work. C G Am F = C | G | Am | F

Output

WAV PCM 16-bit mono 44100 Hz. Compatible with all DAWs, audio players, and audio processing tools.

License

MIT