Some objects come into the world with modest ambitions, and then their owners take them over and make them do something else. The M-Vave FM-1 is one of these. It is a small frequency-modulation synthesizer with 27 physical piano keys and a 1.54-inch TFT screen, sold as a pocket cousin of the Yamaha DX7, and as Nick Indge writes for Ars Technica, it costs $59.72 once fees are added. At release it did what the box said. Nothing more.

In July, people on Reddit’s r/synthdiy forum started reverse-engineering its stock firmware. By September their own firmware was circulating. October is not yet over, and there are already more community projects than one reviewer can cover.

One of them runs Doom.

The concession

Usually, when enthusiasts pry open a closed device, the manufacturer replies with a patch that shuts the door again. On October 17, M-Vave did the opposite. It announced FM1 Open: a software development kit, a browser-based workbench with an emulator for testing custom firmware before it touches real hardware, and a stock firmware now offered as an open platform to flash and build on. The application source is published under GPLv3. Synth Anatomy and other coverage describe the release as the company giving its blessing to custom firmware and community hacks.

Even the version numbers are disputed. Ars Technica says FM1 Open arrived with version 15 of the stock firmware. Synth-news reported that V13 and its development kit went online that day, and M-Vave’s own forum listed FM1 Open V14 soon after. According to Indge, the latest stock package is now v16.

The opening has a clear limit. The synth engine underneath the stock firmware, the part that actually makes the sound, still ships as a closed binary. Only the application layer above it is open. Indge does not think this lessens the gesture. Still, a pattern is worth noticing, offered here as reflection rather than reporting: those who hold power often concede this way. They give up the streets and keep the treasury.

A single flash bank

The freedom carries real risk. The FM-1 runs on a JieLi chip that keeps its firmware in a single flash bank, so if an update is interrupted, the device can be left in a state that is hard to recover. Flashing also wipes everything on the unit, so saved projects and settings have to be backed up first. The installers rely on WebUSB and Web MIDI, which means a Chromium-based browser; Firefox will not work. The synth should be fully charged and connected over USB, and the computer must not fall asleep during the write.

Indge learned this the hard way. His unit arrived running stock v14, and community guides repeatedly warn owners to move to v15 before installing anything custom. He went straight for Doom anyway. The install failed about 80 percent of the way through. The synth still worked, but it no longer spoke the same language as the installers. A “force-flash” tool in M-Vave’s FM1 Workbench restored stock v15 in about 10 seconds.

The community resource hub on GitHub adds its own caution:

While not an absolute hard rule, there is a prominent community recommendation to avoid flashing one custom firmware directly over another.

The hub suggests rolling back to stock v15 through M-Vave’s official updater between builds, or using TransitFM1, a lightweight bridge firmware by Quixotic7 with crash-guarded boot stubs that emulates the stock V15 identity.

What the owners built

First, Doom, because every new machine is asked whether it can run it. On a 240 x 240 display, steered with miniature piano keys, it is a novelty, but Indge found it played surprisingly well. The short draw distance means demons sometimes appear out of nowhere. One port, published on GitHub, fits only the first level, E1M1, because the chip has just 1 MB of flash and 512 KB of RAM.

Melodee looks back to a different era. The stock firmware imitates the DX7. Melodee draws instead on the Casio CZ-1 of the mid-1980s, whose phase-distortion sound modern musicians still chase. It has four engines: a CZ-1 emulator, a DX7-style engine, a percussion engine for 808 drums, and an emulator of the Commodore 64’s SID sound chip. For Indge, a child of the 8-bit years, the result is a chiptune keytar he can carry in his pocket. He even suggests it could recreate the classic Cash Money Records sound associated with Mannie Fresh for about $60.

Felucca is the foundation many other projects build on. The stock firmware plays one instrument at a time; Felucca runs several at once, so a single player can sound like a whole band. Its project page credits Leo Kuroshita of Hügelton Instruments under GPL-3.0-only and lists thirteen engines, from phase distortion to virtual analog, along with a sampler, a 64-step sequencer, and USB audio. Indge also praises its in-browser editor, which spares the user the tiny screen when arranging tracks.

SLOOP, built on Felucca’s engines, turns the FM-1 into a groovebox: a self-contained studio that needs no computer. Drums and bass are programmed on a grid, loops are chained together, and the machine keeps the beat while more layers go on top. Indge calls it an eight-track, battery-powered beat maker built for live performance. Felucca’s documentation describes it as a four-track groovebox with three synth layers and a drum machine.

Then the review moves into the studio. With Felucca installed, Indge connected the FM-1 to his PC over the same USB cable he had used for flashing. Audacity recognized it immediately as a recording device, and any instrument or effect on the synth could be recorded live into its tracks.

It is the same restless curiosity that recently uncovered a hidden radio inside ESP32 chips. Ordinary owners keep digging into the things they bought until those things give up more than was promised. This time the company did not fight them. It opened the gates and kept the engine room locked.