The FM-1 ecosystem

This is the backstory behind the catalog: why this $70 synthesizer could be rewritten, who cracked it, and how the scene is organized. Data is as of 2026-10-09.

The hardware

Introduced in mid-June 2026; in essence it’s the engine of the SMK-37 Pro keyboard (2025) stuffed into a desktop box. It’s manufactured by Zhuhai Shengke (M-VAVE/Cuvave/SINCO are the same company, out of Zhuhai, Guangdong). The current official firmware is V15 (July 30, 2026), which already incorporates community requests: glide, preset copy/rename, operator mute.

About the chip: community documentation describes a JieLi AC791N (WL82) with a proprietary pi32v2 core and external SPI flash — but my board says otherwise: an AC7911B8 with 1 MB of flash integrated on the die (measured via JEDEC, not taken on faith). Probably different hardware revisions; for any memory-budget math, my board wins.

Why it could be hacked

The .fwsc container the updates use is a JieLi UFW (@JMUA + JLUFW) and carries no cryptographic verification: only header, size, and per-block checksum checks. The whole update travels over SysEx on USB-MIDI in a two-step protocol where the device pulls the image from the host — documented byte by byte in AL-255/FM-1-RE and verified by its Linux client. The one hard rule: a custom firmware must keep the bootloader’s OTA handler, or the device goes deaf to future updates.

The short chronology:

• Jul 2026 — AL-255 and aroum publish the complete reverse engineering (chip, memory, OTA protocol). M-VAVE drops V15.
• Sep 4 — first documented unofficial install (a V15 with an altered version number, on real hardware, with rollback). The door was open.
• Sep 26 — Baud Girl releases FM-1_083: the first installable third-party firmware. The scene goes from zero to public in a day.
• Oct 2-3 — Felucca appears (GPL-3.0): the platform almost everything gets built on.
• Oct 4 — the day of the “firmware wars”: SLOOP, X0X, FoMni, and Jangada all on the same day; Groove OS becomes the only paid one ($29 USD).
• Oct 7-9 — second generation (GHOULBOX, ChoralRoot, FiMba-1, Optimist…), Doom on the FM-1, a Hacker News thread, and the community hub already listing 17 GPLs.

And what does M-VAVE think of it all? The best part of the story: when czietz demonstrated through signal analysis that the FM-1’s detune differs from Dexed because they used exp2 instead of exp in the msfa formula, support replied in their Facebook group acknowledging the “implementation adjustment” and saying they’d evaluate fixing it. Zero takedowns, zero lockdowns.

The family tree

Official V15 (stock, 6-op FM derived from Dexed/msfa)
│
├─ (patch) FM-1+VA — Baud Girl, closed source, THE FIRST (Sep 26)
│    └─ (conceptual parent of sloopDX's voice list; no shared code)
├─ (patch) fm1-firmware-patcher — czietz (stock + 4 byte patches)
│
└─ Felucca — Leo Kuroshita / Hügelton, GPL-3.0  ← PLATFORM DONOR
     │  (hardware layer, update loader, installer, storage, editor)
     ├─ SLOOP — isod89 (workflow fork: live groovebox)
     │    ├─ sloopDX — zvenson (SLOOP + a real DX7 inside)
     │    │    └─ zp12 — zvenson (12-bit sampler in the style of the SP-1200)
     │    ├─ Bubba — Erbubar23 (8 tracks, per-track looper, on-device slicer)
     │    ├─ SLOOP Floyd FM — René Bohne (4-op FM engine, visual)
     │    └─ SLOOP DX7 Banks — majnikool (12 DX7 banks)
     ├─ X0X — Charles Vestal (platform fork: 909+808+2×303+breaks)
     │    ├─ FoMni — Charles Vestal (Omnichord-style chord harp)
     │    └─ FiMba-1 — jadamsowers (physically modeled kalimba)
     ├─ Melodee — keremimo (Prophet-5, CZ-1, microtonality)
     │    └─ (its FM6/CZ-1 engines are reused by ChoralRoot)
     ├─ ChoralRoot — Quixotic7 (Telepathic Orchid style)
     ├─ Jangada — zednaked (dark/industrial/Brazilian; sent ratchets upstream)
     ├─ GHOULBOX — Jason Persinger (dungeon synth; sent a reverb fix upstream)
     ├─ Hortator — DEADACTIVE (8-track drums; Mutable Grids/Plaits/Streams)
     ├─ Felucca [Salt] — Chance Roth (Studio in the browser)
     └─ WaveLoop — ELI7VH (live rig with a MiniLab 3)

Almost all the authors send patches back upstream to Felucca or SLOOP. The “war” is a meme war: the hub’s motto is make firmware, not war — you don’t have to pick one forever.

Rescue & tools

The complete ladder for when something goes wrong:

1. OCT− on power-up — the Felucca family’s rescue USB; reinstall from there.
2. Mask ROM download mode — a soft brick falls back to WL82 UBOOT1.00 (a USB mass-storage device); it recovers over the cable with kagaimiq’s jl-uboot-tool. Never write below offset 0x4000.
3. RP2040 dongle — if the chip won’t even enter download mode, a Pico bit-banging the JieLi boot key (0x16EF, ~50 kHz) over the USB wires wakes it up: FM-1-transporter — and my own version, tested against a real brick, in this post.

More ecosystem tools: fm1-emulator (a Rust desktop emulator that runs .fwsc), Quixotic7’s MvaveFM1Unbricker, Keitark’s fm1-nes (the NES as a documented example of bare-metal development), kagaimiq’s JieLi/ghidra-jieli corpus, and awesome-fm-1 as the master list. The community’s center of gravity is r/MVaveFM1.

The other M-VAVE devices

Outside the FM-1 there are hardly any custom firmwares, and some myths deserve busting: the Chocolate/Chocolate Plus has no alternative firmware (it does have a companion-software scene and SysEx RE: pyfootctrl, OpenChocolate, mvave-chocolate-sysex), and the ANN BlackBox has RE and editors but no firmware replacement. The real exception is the SMK-37 Pro — the FM-1’s ancestor, same SoC — with a surgical mod by amalahama that fixes five BLE-MIDI defects. And “SMEG”, “CME”, “25-key Choc”: they don’t exist as M-VAVE products.

Press coverage

The press that has followed the scene: Synth Anatomy (launch, FM-1+VA, Felucca, SLOOP, X0X, Groove OS), MATRIXSYNTH, Sonicstate, Gearnews (“custom firmware is booming”), the ranking of Drey Andersson, and David Hilowitz’s viral video (“FM-1: A full FM synthesizer for $67”, ~1.6M views). On Hacker News, someone summed up the reverse-engineering thread better than we can: “the Flipper Zero of music hacking”.