Groove OS

The ecosystem’s only paid firmware — $29 USD once via Stripe, with all of 1.x included — and also the most conservative: a mod over the stock V15 (“not a replacement”): the FM engine, the 128 presets, the FX, the MIDI/Bluetooth, and the updater are still M-VAVE’s. What it adds is the complete groovebox: 8 tracks, a 64-step sequencer, and a PERFORM page for live use. Drey Andersson gives it 74/100 and calls it “the safest groovebox.”

Workflow

Full beats and live sets across the 27 keys: play with REC off and it keeps your passes as “takes”; PERFORM is 8 mutes + 11 scenes on the keys + 4 “throws” on K1–K4 + 8 punch-ins; DICE rolls pattern variations.

Engines & what it emulates

The stock 6-operator FM intact, plus a new VA (saw/square+PW/tri/sine, SUPER with up to 7 detuned copies, sub, noise, drift, LP24 ladder/LP12/BP/HP with drive) and FM/VA drum kits (PUNCH/DUSTY/STEEL; 12 sounds: 4 kicks, 2 snares, clap, choked hats, ride, rim, perc). Loose DX7 voices over MIDI become a track’s sound; 32-voice banks open in the browser. No sampling. The engine count is disputed (Synth Anatomy counts a fourth, “acid”) [unresolved].

What sets it apart

• 8 tracks with their own 1–8 bar lengths (polyrhythm); 20 voices of polyphony (12 FM + 8 VA); 179 sounds (242 with the included 63-sound VA pack).
• Patches three stock flaws: detune, LFO speed, and stuck notes.
• Hold OCT− + OCT+ at power-on and the stock FM-1 boots — unique among all the ecosystem’s firmwares; projects export as .groove (2–4 KB).

Status & caveats

Stable and maintained; an installer with SHA-256, resumable, that restores V15 “even from a device stuck in its updater” — though that wipes the Groove projects. Synth Anatomy’s objection sums up the controversy: “it’s a shame it isn’t open-source; it bothers me a bit to pay for something that can indeed brick the hardware.” The other closed option — free — is Baud Girl’s FM-1+VA.