GR!MM

Dark ambient, dungeon synth and deathdream firmware for the M-VAVE FM-1.

Try it in your browser (the real firmware, no FM-1 needed) · Open the editor (edit sounds live, load samples, back up your FM-1)

GR!MM turns the FM-1 into a four-track drone and atmosphere machine: seven sound sources, long dark effects, a 64-step sequencer per track, one-key chords, an arpeggiator, song mode and live performance tricks. Everything is drawn in a pixel-brutalist style, with an eye that watches the music and candles that burn with each track.

Free and open source (GPL-3.0). Unofficial firmware, not made or endorsed by M-VAVE. Install at your own risk.

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What's inside

• 4 tracks, 6 voices shared between them
• 7 sources: VA (analog-style, with supersaw), FM (6-operator, fully editable), SAMPLE (a sample played like a tape loop), VOICE (formant choir), WHEEL (tonewheel organ), PHYS (bowed and struck physical models), PHASE (CZ-style phase distortion)
• 40 factory sounds in 8 categories (PAD, DRONE, BELL, VOICE, ORGAN, KEYS, OTHER, TEXTURE), plus 64 slots for your own, with names you give them in the editor
• 4 factory samples (URCHIN, LEAVE, NIKOLAI, M-SOFT; CC0) in the four sample slots, which you can replace with your own (6.6 s each)
• Effects: TAPE (wow, saturation, hiss over the whole mix), GRAIN (a granular cloud with FREEZE), DELAY (tape echo) and SPACE (reverb up to ~32 s, and infinite)
• Per track: envelope, LFO, filter, scale snapping, one-key chords, arpeggiator, latch for drones
• Sequencer: 64 steps per track, chance, ratchets, note lengths, step locks, chord steps, tools (random, mutate, shift, double, copy/paste)
• Song mode: four slots A–D, chained by hand or recorded live
• Performance layer: freeze, reverb and echo throws, tape stop, reverse, filter sweeps, stutter
• Autosave: the FM-1 comes back exactly as you left it
• MIDI: in and out over USB, MIDI learn, sequencer and arp out; the FM-1 is also a USB audio input for your computer
• Battery level in the HOME header

Install

1. Open the FM-1 Firmware Hub in Chrome or Edge.
2. Connect the FM-1 over USB.
3. Pick GR!MM and press install.

Updates appear on the hub automatically when a new release is published here.

If GR!MM isn't on the hub yet, or you want to install a release file by hand: download grimm.fwsc from Releases, then, with Python 3 and py -m pip install mido python-rtmidi:

py tools\fm1_install.py grimm.fwsc

Your sounds, slots A–D, settings and samples stay on the FM-1 when you update. If anything goes wrong, the hub's Rescue page brings a stuck FM-1 back.

Learn it

• The manual: every button, page, knob and combo, in plain English.
• Quick start: switch on, wait for the eye to open. Turn ALGORITHM to pick a track, turn PRESETS to pick a sound, play the keys. Hold SEL for one-key chords. Press FX for the effects.

The editor and the demo

Both run in Chrome or Edge on a computer, nothing to install.

• The editor: connect the FM-1 over USB and edit the four tracks' sounds with big sliders: every move plays on the FM-1 at once, like turning its knobs. Store sounds into your 64 slots with a name, browse the factory sounds, load WAV files into the sample slots, and back up or restore everything. Without an FM-1 it runs GR!MM's own code in the page (TRY WITHOUT AN FM-1).
• The demo: the FM-1's panel on screen, running the same firmware. Play it with the mouse or the computer keyboard (the keys are listed under the panel and in the manual).

Your own samples

GR!MM has four sample slots that survive firmware updates. They come with the four factory samples; replace any of them with your own:

1. Open the editor, connect the FM-1, and go to SAMPLES.
2. Drop a WAV on a slot (any rate, mono or stereo; up to 6.6 s are kept), check its name and root note, press UPLOAD.

Then set a track's source to SAMPLE and pick the slot. RESTORE FACTORY SAMPLES (in the editor, or SYSTEM 2 on the FM-1) brings the four factory samples back.

Optionally, from a command line with Python 3:

py tools\fm1_sample_upload.py 2 "your-sound.wav"
py tools\fm1_sample_upload.py --list

Screens

Credits

GR!MM stands on the shoulders of other people's open work. Full details and licence texts are in LICENSING.md and LICENSES/.

• Felucca by Leo Kuroshita / Hügelton Instruments (GPL-3.0): the platform, and the ANALOG, FM6, GRAIN, HALL, formant, tonewheel, physical-modelling and phase-distortion engines GR!MM builds on
• Dinghy by zvenson (GPL-3.0): the firmware template
• SLOOP by isod89 (GPL-3.0): the FM-1 platform work Felucca and Dinghy share; its editor's layout and live editing inspired GR!MM's editor
• X0X by charlesvestal (GPL-3.0): the tape delay's design and the browser build's approach
• msfa, the FM core from Dexed (Apache-2.0)
• DaisySP and Mutable Instruments Rings (MIT), via Felucca's physical models
• CrispyZebra by Leo Kuroshita (GPL-3.0), via Felucca's phase distortion
• Press Start 2P font by CodeMan38 and Terminus font by Dimitar Zhekov (SIL Open Font License 1.1)

Building from source

See docs/BUILDING.md.

Licence

GPL-3.0. See LICENSE. The four factory samples are CC0 1.0: free to use for anything. Bugs and questions: open an issue on this repository.