DX7

A Yamaha DX7 FM synthesizer emulator in Rust.

Demo

E.PIANO 1 solo — "Greatest Love of All" intro (DX7's iconic FM electric piano):

https://github.com/knoguchi/dx7/raw/main/demo/epiano1_intro_demo.mp4

Structure

• dx7-core — Platform-independent synthesis engine (no_std capable, zero dependencies). See dx7-core/README.md.
• dx7-midi — no_std USB-MIDI / BLE-MIDI parsers, message queue, General MIDI sound set. See dx7-midi/README.md.
• dx7-app — Desktop CLI: real-time audio, MIDI input (USB, optional BLE and RTP-MIDI), computer keyboard, MIDI file rendering.
• dx7-rp2350 — Firmware for Raspberry Pi Pico 2 W (10 voices, BLE MIDI as the primary input, USB MIDI too, PWM audio). See dx7-rp2350/README.md.
• dx7-esp32s3 — Firmware for ESP32-S3 boards (8 voices, BLE MIDI as the primary input, USB MIDI too, ES8311 I2S codec, round LCD with touch). See dx7-esp32s3/README.md.

Build

cargo build --release          # dx7-core, dx7-midi, dx7-app
cargo test                     # engine, parser and renderer tests

The firmware crates are excluded from the workspace and built from their own directories with their own targets; see their READMEs.

Optional desktop features:

cargo build --release -p dx7-app --features bluetooth   # BLE MIDI peripheral (macOS, Linux/BlueZ)
cargo build --release -p dx7-app --features rtp-midi    # Apple Network MIDI (RTP-MIDI) listener

Usage

Interactive mode

Play with computer keyboard or a connected MIDI controller:

cargo run --release --package dx7-app

Keyboard controls:

• ASDFGHJKL; — white keys (C4-E5)
• WETYUOP — black keys
• Z/X — octave down/up
• 1-9,0 — select patch
• Q, Esc, Ctrl-C — quit

Key release needs a terminal that supports the kitty keyboard protocol (iTerm2, kitty, WezTerm, foot). On Terminal.app a note sustains until the key is pressed again. MIDI Program Change switches patches live.

Load patches from SysEx

cargo run --release --package dx7-app -- --sysex sysex/factory/rom1a.syx --patch 0

Render a single note to WAV

cargo run --release --package dx7-app -- --render output.wav --note 60 --velocity 100 --duration 3

Render a MIDI file to WAV

cargo run --release --package dx7-app -- --midi-file song.mid --sysex sysex/factory/rom1a.syx --patch 3 --render output.wav

GM mode

Render a MIDI file using the built-in General MIDI sound set (128 programs mapped to DX7 patches):

cargo run --release --package dx7-app -- --midi-file song.mid --render output.wav --gm

Use --track 1 --track 2 to render specific tracks only. Other render options: --ch 2=file.syx:21@1.5,0.3 maps a channel to a patch with volume and reverb send, --dry disables the effects chain, --no-normalize keeps absolute levels, --sample-rate 48000 sets the output rate (44100 or 48000).

List MIDI ports

cargo run --release --package dx7-app -- --list-midi

SysEx Banks

The sysex/ directory contains DX7 patch banks organized by source:

• factory/ — 8 official factory ROM banks (ROM1A–ROM4B)
• vrc/ — 24 Voice ROM Cartridge banks (VRC101–VRC112)
• greymatter/ — Grey Matter E! expansion banks
• KV-06 Shofuku Gaiden/ — community bank

Engine

• 6 identical FM operators with 32 algorithm topologies and feedback
• 24-bit phase accumulator, 10-bit sine ROM in log domain
• Integer log/exp domain math in the style of the YM21280 OPS chip
• Per-operator amplitude envelopes with hardware-measured stage timing, pitch envelope, LFO
• Keyboard level/rate scaling, velocity, mod wheel, pitch bend with configurable range (RPN 0), sustain pedal
• Voice stealing with a one-block fade (no clicks)
• Desktop output chain: DC blocker, soft saturation, stereo reverb, chorus, tremolo, exciter
• Firmware output chain: DC blocker and 4th-order Butterworth low-pass at 10.5 kHz (DX7 reconstruction filter)
• GM sound set with 128 programs and synthesized drum machine (channel 10)

License

Apache-2.0, see LICENSE. Third-party attributions (MSFA, Freeverb) and a note on the embedded factory voice data are in NOTICE.

Reference

• music-synthesizer-for-android (msfa) engine, Apache-2.0
• OPL3 FPGA math notes for the log-domain operator technique