M-VAVE FM-1 custom firmware is software for the synthesizer, and stock V16 and FM1 Open V14 are separately versioned branches, not successive releases. That matters because compatibility and sample backups depend on the specific branch and project.
Stock V16 and FM1 Open V14 are separate branches
M-VAVE lists stock FM-1 firmware V16 with the date October 21, 2026. Its separate repository identifies FM1 Open as V14. The version numbers belong to different branches, so V14 does not mean FM1 Open is an earlier step on the way to stock V16.
| Firmware branch | Listed version | Role |
| Stock firmware | V16 | M-VAVE’s firmware listing for the FM-1 |
| FM1 Open | V14 | A separate open development branch with its own application and workbench |
M-VAVE’s FM-1 product page lists the stock branch, while its FM1 Open repository describes the separate branch and its documentation. FM1 Open’s application is licensed under GPLv3 with an FM1 SDK linking exception; the synthesizer engine is a binary SDK under separate terms.
Sample storage requires its own backup
FM1 Open V14 documents eight tracks, eight sample slots and 16 FX demos. The eight slots share about 19.55 seconds of new sample storage. Project files do not contain the sample audio, so back up the sample bank separately from project files.
The repository also cautions that switching firmware does not make project and sample formats interchangeable. Older firmware may not support FM1 Open V14 track preferences, its independent voice library, or extended and synchronized delay settings. A project backup alone therefore may not preserve the separate samples or settings you use in FM1 Open.
Compatibility advice is project-specific
FM1 Open’s documentation says its workbench can restore original stock V15 and migrate from compatible third-party firmware. It describes compatibility checks with selected versions, rather than every third-party release.
Ars Technica reported community advice to return to stock V15 between custom firmware builds, while describing that advice as not an absolute rule. M-VAVE’s stock V16 listing and FM1 Open’s V14 documentation refer to different branches and scopes; neither makes V15 a universal starting point. Check the instructions for the particular firmware you plan to install.
Browser preview and hardware flashing are different tasks
FM1 Workbench can preview the instrument and manage projects, samples and voices. A separate, unofficial browser tool called fm1-emu is described by Bedroom Producers Blog as a way to run FM-1 firmware before installing it on the hardware. That publication reports MIDI input support in Chrome, Edge and Firefox, no MIDI input in Safari, and no MIDI output. Those emulator capabilities do not describe the requirements for flashing a physical FM-1: Ars Technica says its browser-based installers use a Chromium browser with WebUSB and Web MIDI.
A reported flash failure shows why backups matter
Ars Technica’s Nick Indge reported that flashing erases saved projects and settings, and that the FM-1 uses a single flash bank. In his account, a Doom firmware installation from stock V14 failed at about 80%; FM1 Workbench’s force-flash tool then restored stock V15 in about 10 seconds. Indge also reported making a four-track loop with Felucca after about 15 minutes of exploring it, with Audacity recognizing the synthesizer over USB as an audio recording device.
Before changing firmware, back up projects and sample banks separately. Ars Technica’s account also recommends keeping the device charged and avoiding disconnection, shutdown or computer sleep during a firmware write.
