M2DX

MIDI 2.0 + DX7-compatible FM Synthesizer

Download on the App Store

Welcome to M2DX support.

M2DX is a MIDI 2.0-compatible DX7 FM synthesizer for iOS, delivering classic 6-operator / 32-algorithm FM tones reimplemented entirely in Swift 6. The synthesis engine is provided by the M2DX-Core library.

New in 1.7.1: a redesigned app icon — a vintage FM hardware panel with a dot-matrix display, including dark and tinted variants for iOS 18.

Download

iOS / iPadOS 18+ — get M2DX from the App Store:

  1. On your iPhone / iPad, open the M2DX App Store page
  2. Tap Get to download and install
  3. Launch M2DX and play right away with the on-screen keyboard — a MIDI controller is optional

Current Status & Roadmap

M2DX is available now and fully playable. In the spirit of transparency, here are the areas we are still actively refining — your feedback helps us prioritize.

MIDI 2.0 coverage is limited

  • We have not been able to procure enough MIDI 2.0-capable hardware, so UMP behavior has only been verified across a limited set of device combinations
  • Differences in MIDI 2.0 support across macOS versions (CoreMIDI behavior, etc.) are not fully characterized
  • Vendor-specific extensions and proprietary profiles built on top of MIDI 2.0 have only been partially analyzed (specifically, parts of KORG's implementation); other vendors' proprietary implementations remain untouched

DX7 preset compatibility

  • 32 initial presets are bundled, but the tonal character compared to vintage FM has not been fully verified across all presets
  • Bank loading and SysEx patch import compatibility will be improved progressively across upcoming updates

FX chain

  • The 6-stage FX chain (EQ → Drive → Chorus → Reverb → Stereo → Maximizer) is at the "working implementation" stage. Musical tuning of parameter ranges and endpoints, CPU efficiency, and interaction optimization are still ahead

If you spot bugs or oddities

Crashes are auto-reported via Firebase Crashlytics (see the Privacy Policy for details). Reproducible issues are easier to fix — if you can, please send a report to support@hakaru.net.

Features

Full MIDI 2.0 UMP Support

Native Universal MIDI Packet (UMP) decoding with 16-bit velocity (65,536 levels), 32-bit CC values, and 32-bit pitch bend for smooth, expressive control. MIDI 1.0 fallback is automatic.

DX7-Compatible FM Engine

A 6-operator / 32-algorithm DX7-style FM synthesis engine implemented in pure Swift. Int32 Q24 fixed-point arithmetic targets the character of vintage FM. 32 initial presets are bundled.

16-Voice Polyphony

16 simultaneous voices with sustain pedal (CC64) and pitch bend (±2 semitones) support. Padé-approximation tanh soft-clipping prevents digital distortion.

6-Stage FX Chain

EQ → Drive → Chorus → Reverb → Stereo → Maximizer signal chain. Every parameter can be MIDI Learn-mapped to any CC.

MIDI-CI Property Exchange

Exposes 155+ parameters in a hierarchical namespace. Compatible DAWs and controllers auto-discover parameters, with JSON-based preset management (no SysEx required) — a self-describing instrument.

Low Latency

AVAudioSourceNode direct rendering drives the FM engine inside the CoreAudio render callback, eliminating buffer-queueing overhead. The iOS IOBufferDuration (~5 ms) is the effective latency floor.

AUv3 Plug-in

M2DX ships an AUv3 instrument plug-in ("M2DX FM Synthesizer") that loads inside GarageBand, AUM, Logic Pro and other AUv3 hosts, with host automation routed over NRPN. The standalone app is included too.

M2DX Pro

Everything described above is free. M2DX Pro is an optional one-time unlock — no subscription — that adds deeper layering and vintage sound-engine options:

  • TX816 LAYER — stack up to 8 patches per note, with save & recall of your layered stacks
  • FM engine choice — switch between the Modern engine and Mark I, with Mark I depth control (÷2–÷16)
  • Vintage 12-bit DAC emulation for a grittier, hardware-flavored output stage
  • Voice Stack — up to 16× unison per note

Pro features work in both the standalone app and the AUv3 plug-in. Unlock M2DX Pro — and use Restore Purchases — from the M2DX Pro section in Settings. The unlock is one-time and supports Family Sharing.

System Requirements

  • iOS / iPadOS 18+ (available on the App Store)
  • macOS support is planned for the future

FAQ

I can't find M2DX in the App Store yet

A new release can take a few hours to propagate across all regional storefronts. If the link above doesn't open the page right away, please try again shortly.

What happens if the app crashes?

Starting with v1.3.1 (build 5), Firebase Crashlytics auto-reports crashes. Reproducing a crash helps us identify and fix it quickly. See the Privacy Policy for details on the data we collect.

Can I load DX7 SysEx presets?

32 initial presets are built in. SysEx import for user-supplied banks will be announced in upcoming updates.

Do I need a MIDI 2.0-compatible DAW?

No. MIDI 1.0 fallback is automatic, so any traditional MIDI controller or DAW works. A MIDI 2.0 environment unlocks higher-resolution expression.

Is M2DX available as an AUv3 plug-in?

Yes. M2DX includes an AUv3 instrument plug-in ("M2DX FM Synthesizer"), so you can play it inside GarageBand, AUM, Logic Pro and other AUv3 hosts. The standalone iOS / iPadOS app is included as well.

Is M2DX free? What is M2DX Pro?

The app is free, including the AUv3 plug-in and the full MIDI 2.0 / FM engine. M2DX Pro is an optional one-time unlock that adds TX816 LAYER, the Mark I engine and Vintage 12-bit DAC, and up to 16× Voice Stack unison. There is no subscription.

I unlocked M2DX Pro but the features aren't showing

Open Settings → M2DX Pro and tap Restore Purchases, and make sure you're signed in with the same Apple Account you used to buy it. The Pro unlock is one-time and supports Family Sharing.

Links

Contact

For questions, bug reports, and feature requests, please reach out at:
support@hakaru.net