SLOOP Floyd FM

A live groovebox firmware for the M-VAVE FM-1 — for any style.
Free and open source (GPL-3.0), based on Felucca by Leo Kuroshita / Hügelton Instruments.

Install from the browser · Complete guide · Manual · Guide en français · Web editor · Releases · Report a bug

SLOOP turns the FM-1 into a four-track groovebox you play live: three synths and a drum machine with 16 sounds on the white keys, ten synthesis engines, 76 sounds, 37 drum kits, your own samples, a song mode you play with your hands, USB audio, MIDI in on the jack and MIDI clock — and now six-operator FM with DX7 patches, parameter locks, micro timing, fills, a quick chain of sections and the sequencer to MIDI out. House, techno, hip-hop, trap, drum & bass, amapiano, synthwave, lo-fi, ambient, chiptune — it does not pick a style for you. No factory patterns, nothing to load: everything you hear, you play.

Status: 2.4.1 (a hotfix of 2.4: imported DX7 patches no longer play noise). Still a beta: install at your own risk, and please report what you find. Your projects, presets, samples and settings are kept when you update, and you can go back at any time (see Going back).

Contents

1. What's new in 2.4.1 and 2.4
2. Screenshots
3. Features
4. Install
5. Your first beat in 60 seconds
6. The controls
7. The menu: settings of the FM-1
8. MIDI and USB audio
9. The web editor
10. Compatibility
11. Troubleshooting
12. Specifications
13. Documentation
14. Building and tests
15. Contributing
16. Credits and thanks
17. Licence

What's new in 2.4.1

Imported DX7 patches no longer play noise. An FM6 operator with amplitude modulation sensitivity (AMS above 0, about one DX7 patch in four) turned into noise and static, worse with every key held: a wrong calculation gave it a random level. Those patches now sound as on a DX7. The factory FM6 sounds were not affected. Thanks for reporting it!

What's new in 2.4

Projects, autosaves and backups from 2.3 load as they are. The full list, and what came before: SLOOP.md.

What's new in 2.3

The full list, and what came in 2.0, 2.1 and 2.2: SLOOP.md. Release notes: Releases.

Screenshots

_{The FM-1's screen in 2.3: the tracks, the REC screen and its count-in, the menu (lights and USB audio), MIDI clock, about.}

_{Start-up, the four tracks (recording), the drum grid and the acoustic kit, the sounds by kind, the layers (punch-in FX, steps, key and chords, mix, erase), a free take, the FX sends.}

_{The web editor: the drum track as a 16-lane grid, with levels and ratchets.}

_{CHOP: a 20 s recording cut into 16 chops, 8 kept, fitted to the slot.}

Features

Play it live: hold a button, touch a key

Every function button is a layer: hold it and the 16 white keys and the four knobs change job, and the screen shows how. Tap it and its pages open. Hold a layer button and tap HOME to lock it open, both hands free.

Keys 1, 5, 9 and 13 glow dimly while a layer is held: the first key of each row of the 4 × 4 grid on the screen. EDIT + OCT− / OCT+ is undo / redo.

Drums

• 16 sounds on the white keys, kick to cowbell; a black key doubles the white key on its left (fast rolls with two fingers).
• Ghost and hard hits: hold OCT− / OCT+ while you play. Every hit keeps its level (GHOST, SOFT, NORM, HARD) and a ratchet (x1–x4).
• 37 kits, all level-matched: a sampled acoustic kit in 5 treatments (CC0 studio recordings) and 32 synthesised kits — 808, 909, 606, 80s, vintage, trap, drill, boom bap, lo-fi, phonk, house, deep house, techno, minimal, electro, disco, UK garage, jungle, dubstep, reggaeton, amapiano, afrobeat, latin, tribal, synthwave, chiptune, arcade, glitch, industrial, hyperpop, ambient, jazz brushes. Each synthesised sound is built like on the classic machines; softer hits are darker as well as quieter. Your own kits too (2.4): KIT USR1–USR4 (or USR3+4, about 15 s) plays sample slots you fill in the editor's Drum kit page, a sound of yours per lane.
• Grid and kit pages on the FM-1 (EDIT or SEQ on the drum track): on the grid, the keys are the steps of the sound you pick (and you hear it); a 16-lane grid in the web editor.

Synths and sounds

• Ten engines: analog, 4-op FM, 6-op FM with DX7 patches (FM6, 2.4), phase distortion, three-oscillator, tonewheel organ, formant voice, granular, lo-fi chip, sampler.
• 76 sounds, browsed by kind — basses (sliding 808s, acid 303, reese, FM), keys (Rhodes, a real Steinway grand, house and afro keys), organs, pads, leads (supersaw, talkbox), plucks and bells, stabs and dub chords — every one level-matched. 32 slots for your own presets.
• Envelopes (with a pitch punch for 808s), LFO, arpeggiator, glide and voice modes (POLY, MONO, LEGATO, UNISON), per-track drive and slicer, sends to a stereo chorus, a tempo delay (dotted 1/8 and 1/16 too) and a stereo reverb.
• Key and chords (SCL): the key of the song for all synths, 16 scales, one-key chords (triad, 7th, 9th, sus4, power), keys snapped to the scale or the scale on the white keys.

Recording and the sequencer

• Records as you play, no click needed: while it plays, REC records at once and every pass is added on top (overdub). Notes land where you heard them: the ~12 ms of the keys are taken back.
• The REC screen (2.3): mode free — no tempo, no grid: play, press REC on the "1" after your last bar, and the loop's length sets the tempo — or tempo — record at the tempo you set; length 1, 2 or 4 bars; start on your first note, or after a one-bar count-in.
• Hold REC ~2 s to clear a track; undo / redo brings it back.
• 64 steps per track, each track with its own length and division, 1/32 to two bars (polymeters stay in phase); chords up to 4 notes a step, ties, slide; MPC swing 50–75 %; one sample-accurate clock for everything: no drift at any tempo.
• Parameter locks, micro timing and fills (2.4): hold a step to give it its own value of any sound parameter, to nudge it off the grid, or to make it play only (or never) during a fill.
• The PLAY light flashes on every beat (a visual metronome); an audible click is in GLO → GLOBAL → CLICK and is never recorded.

Songs

Save up to four sections A–D (SAVE + keys 5–8), play them live on the next bar (SAVE + keys 1–4), and record the song as you play it (SAVE + key 14). Keep SAVE held and tap several sections for a quick chain (2.4). In song mode PLAY plays the whole chain. The SONG screen edits it by hand.

Effects and master

• 16 punch-in effects (FX + a key), locked to the tempo.
• Master: DUST (an old sampler and a record: bits, rate, crackle), DUCK (the kick pumps the synths), FILT (a DJ filter: low-pass ← off → high-pass), and an output limiter.

Your own samples

• Four slots (USR1–USR4) of about 7.4 s each, played by a synth track or as a drum kit (USR3+4: one kit of about 15 s); up to 16 WAV files per slot, each on its own key.
• CHOP in the web editor: open or drop a recording (WAV, MP3, AIFF…) of any length, tap along while it plays (each tap snaps to its hit), or find the hits, a tempo grid, equal parts; keep the chops you want, shorten them or Fit to slot; send them to a slot, one per key, or download them as WAV files.

MIDI

• USB MIDI in and out, class compliant.
• TRS MIDI IN (the 3.5 mm jack, 2.3) for a keyboard or a pad controller.
• MIDI clock in (USB or TRS): tempo, START, CONTINUE, STOP.
• MIDI out: the keys always; the sequencer, the arp and the rolls too with GLO → SYSTEM → MIDI = SEQ (2.4).
• Details: MIDI and USB audio.

USB audio (2.3)

The FM-1 is also a USB audio input: record its master output on a computer, no driver, over the same cable as MIDI and the editor. Details: USB audio.

Lights for playing in the dark (2.3)

Every button can glow so its label is readable on a black FM-1; the C keys or every white key can glow too; the notes playing can light their keys. Details: The menu.

Memory and safety

• Autosave: stop and leave it 2.5 s, your work is kept; at power-on SLOOP comes back exactly as you left it.
• 4 projects, 32 user presets, 27 FM6 patches, undo / redo.
• Full backup and restore from the web editor (2.3).
• Safe updates: the installer checks the package (SHA-256) before writing it, the update loader checks it again (CRC) before starting it; an interrupted install finishes when you press Install again; USB rescue (OCT− at power-on).

Install

From the browser (recommended)

1. Open the SLOOP installer in Chrome or Edge on a computer.
2. Connect the FM-1 by USB — a data cable, directly (no hub).
3. Press INSTALL, allow MIDI access, and wait for Done. The FM-1 restarts on the SLOOP logo.

Nothing to download or compile. Your projects, user presets, samples and settings are kept. After an install, unplug and plug the FM-1 back in once so the computer finds its USB audio input.

Other ways

• Python: the .fwsc of a release with python tools/fm1_install.py sloop-2.4.fwsc (needs pip install mido python-rtmidi).
• Build it yourself: see Building and tests; on Windows, INSTALL-SLOOP.bat builds SLOOP and opens the installer locally.

Going back

• To an earlier SLOOP: install the .fwsc of its release (for example 2.3). Your samples, user presets and settings stay. Projects saved by 2.4 (format FUN5: locks, nudges, fills) do not open in 2.3 or older — 2.3 sees them as empty, and its autosave can write over the music in progress; a 2.4 backup restores into 2.4 only. Save a backup before you go back, and restore it once you are on 2.4 again.
• To the official firmware: on the installer page, open Return to the official firmware (V15). Save a backup with the editor first, download FM-1 V15 from m-vave.com and select its FM-1.fwsc — only that exact file is accepted. M-VAVE's updater, M-UPGRADE, works too. To come back, install SLOOP again and restore your backup.

Rescue

• The FM-1 no longer starts SLOOP: hold OCT− alone while switching it on (SLOOP USB RESCUE), then install again.
• An install was cut off: the FM-1 stays in update mode; press INSTALL again and it finishes.
• If an FM-1 no longer starts at all, recovery needs FM-1-transporter.

Custom firmware is installed at your own risk. No warranty.

Your first beat in 60 seconds

1. ALGORITHM to track 4 (orange, drums). The white keys are 16 drum sounds; PRESETS picks a kit (try 808 or BOOMBAP).
2. Press REC and play a beat freely, at your own tempo. Hold OCT− while you hit for ghost notes, OCT+ for hard ones.
3. Press REC on the "1" after your last bar. The loop closes, its length sets the tempo, the hits snap to the grid and it plays at once. (Prefer a set tempo, or a count-in? Turn KNOB 1 and KNOB 3 on the REC screen before you start.)
4. REC again while it plays: you record on top. Hold ARP and hold the hat key for a hat roll.
5. ALGORITHM to track 1, REC, play a bass line. Hold SCL and press the key of your song; on track 2, hold SCL and turn KNOB 1 to 7TH: every white key now plays a chord.
6. Hold FX and press a white key for a punch-in effect; still holding FX, turn KNOB 2 for DUST, KNOB 3 for DUCK.
7. A mistake? Hold EDIT and press OCT−: undo.

The controls

Colours: blue track 1 and KNOB 1, green 2, yellow 3, orange 4 (drums). White is what you touch; red is recording.

The menu: settings of the FM-1

Hold HOME. The menu is in four sections, as the pages are: SCREEN (COLOR, ZOOM), LIGHTS (LIGHTS, KEYS, NOTES), AUDIO (LOWCUT, USB AUDIO, USB SERIAL), SYSTEM (HARDWARE CALIBRATION, ABOUT). SELECT goes from one section to the next, KNOB 1, 2, 3 set the section's rows (each row shows its knob's colour), PRESETS moves the cursor, OCT+ steps the cursor's setting round or opens it (CALIBRATION, ABOUT), OCT− closes. These are settings of the FM-1, not of a project: loading a project or NEW PROJECT does not change them, and the backup keeps them.

Two more settings of the FM-1 live elsewhere: SYNC (GLO → SYSTEM: INT, USB or TRS) and the REC screen's mode and start.

MIDI and USB audio

MIDI in

SLOOP takes MIDI from two places at once:

• The MIDI IN jack (3.5 mm TRS): a keyboard or a pad controller with a MIDI output, through a TRS-to-DIN MIDI adapter. If nothing plays, try the other adapter type (A / B).
• USB, from a computer or a phone (a DAW, a MIDI routing app) or a USB MIDI host box.

A USB keyboard plugged straight into the FM-1 cannot work: both are USB devices, and a USB link needs a host (a computer, a phone, or a USB MIDI host box). Bluetooth MIDI is not supported: SLOOP, like Felucca, never switches the radio on.

MIDI out

What you play on the keys always goes out on USB MIDI, each track on its channel (1–3 the synths, 10 the drums). GLO → SYSTEM → MIDI = SEQ sends what the sequencer, the arp and the rolls play too: every note is ended, STOP ends whatever was still on, and notes that came in from a computer or the jack are never sent back. Record the FM-1's MIDI in a DAW and you get your pattern as notes.

MIDI clock in

GLO → SYSTEM → SYNC = USB or TRS (INT: SLOOP's own tempo). START plays from the top, CONTINUE carries on, STOP stops; the tempo follows the master and the steps follow its 24 pulses a beat, so SLOOP never drifts. When the clock stops for half a second, PLAY on the FM-1 plays at its own tempo again.

Clock only (2.4): GLO → SYSTEM → IN = CLOCK: SLOOP follows the clock and ignores incoming notes, handy when a DAW or a sequencer also sends notes to other gear.

USB audio: record the FM-1 on a computer

On USB the FM-1 is also an audio input named "Felucca": 44.1 kHz, 16-bit stereo, class compliant — no driver on Windows, macOS or Linux. Choose it in your DAW or in Audacity and record: you get the master output, exactly what the headphones play (after DUST, DUCK and FILT). MIDI, the web editor and the installer keep working on the same cable.

• The level: HOME menu → USB AUDIO. MASTER (default): the recording follows the MASTER knob, as the headphones do — keep MASTER well up while you record. FULL: a fixed level, as with MASTER all the way up, kept from clipping by the limiter; MASTER then only sets the headphones (the right choice for an interface with no level control).
• The first time (and after an install), the computer sets the FM-1 up again as a MIDI + audio device: unplug and plug it back in if the input does not show. The MIDI port keeps its name.
• The audio input comes from Felucca 1.0.

The web editor

Open it from the installer page (or the editor link) in Chrome or Edge, with the FM-1 on USB, and press Connect. It follows the device live: turn a knob on the FM-1 and the editor moves.

• Sound — every parameter of the selected track, the engines and the presets; on an FM6 track the FM6 panel: every operator, the bank, Import / Export SysEx (DX7 voices and banks).
• Sequencer — the steps; on the drum track a grid of 16 sounds × the steps, with levels and ratchets, and the kit. Click a step for its nudge, parameter locks and fill condition.
• Tracks — the four channel strips.
• Library — your user presets and preset files.
• Samples — the three user slots, files and CHOP.
• Projects — the four projects, and Backup: Save a backup writes everything on the FM-1 to one file (with the FM6 bank); Restore from a file puts it all back (stop playback first).
• Settings — global, master (DUST, DUCK, FILT, ROLL), drums.

The protocol is documented in web/EDITOR_PROTOCOL.md.

Compatibility

Troubleshooting

The installer or the editor does not find the FM-1. Use Chrome or Edge, a data cable, no hub, and allow MIDI access. Close every other app or tab that uses MIDI (a DAW, M-UPGRADE, another editor tab), then reload the page.

An install stopped half-way. The FM-1 waits in update mode: press INSTALL again. If SLOOP no longer starts, hold OCT− alone while switching on (SLOOP USB RESCUE) and install again.

The black keys make no sound on a synth track. That track plays chords or the scale on the white keys (in chord mode the black keys change the chord: CHORD+): hold SCL (between FX and ENV) and set KNOB 1 CHORD to OFF and KNOB 3 KEYS to OFF. The drum track always uses the black keys.

Nothing plays from the MIDI IN jack. Try the other adapter type (A / B); check the keyboard's channel (1–3 synths, 10 drums, 4–16 the selected track).

The USB audio input does not show. Unplug the FM-1 and plug it back in (after an install the computer must find it again). On a Mac (macOS 13–15), check that HOME menu → USB SERIAL is OFF (the default), then restart the FM-1. In Audacity: Transport → Rescan Audio Devices. On Windows: Sound settings → Recording → show disabled devices.

The USB recording is too quiet, or follows the volume knob. Set HOME menu → USB AUDIO to FULL, or turn MASTER up.

Recorded notes move to the grid. SLOOP quantises what you record to the steps of the track (its DIV: 1/4 … 1/32, triplets). For finer timing, set DIV to 1/32, or hold the step and nudge it (KNOB 4); for groove, use SWING.

Notes fade out on a dense part. The processor is at its limit: SLOOP fades one voice at a time (never the bass or the lead) rather than glitching. Fewer held notes or a lighter engine help.

An FM6 sound changed after loading a project. A project keeps the track's patch slot (PTCH), not the patch itself: store a patch you edited in the bank (editor → FM6 → Store in bank) and set PTCH to it.

The lights or SYNC went back to OFF / INT. You went back to an earlier SLOOP, which does not keep them; set them again in 2.4.

Something else? Open an issue: what you did, what you expected, what happened, and the version shown in HOME menu → ABOUT.

Specifications

Documentation

• GUIDE.md — the complete guide: every button, combination, layer, page, engine and editor page, with a one-page cheat sheet
• SLOOP.md — the manual (every page, layer, sound and kit) and the history of each version
• DEMARRAGE-RAPIDE-FR.md — guide de démarrage en français
• BUILDING.md — building, build options and tests
• web/EDITOR_PROTOCOL.md — the editor's SysEx protocol
• LICENSING.md — the licences of the code and the assets

Building and tests

See BUILDING.md. In short: the JieLi toolchain and three files of the AC79 SDK, then ./build.sh (Linux / macOS) or INSTALL-SLOOP.bat (Windows with WSL), which builds the firmware and serves the installer and the editor on http://localhost:8766.

tests/run_tests.sh runs the host test suite with no hardware: audio renders against golden hashes, CPU budgets, the sequencer's timing (no drift, swing, ratchets, rolls, the REC modes and the count-in, MIDI clock), the UI pages and layers, the knobs, flash storage, the update loader, MIDI and USB audio, and the web pages (editor, backup, CHOP, installer).

Contributing

• Bugs and ideas: open an issue — what you did, what you expected, what happened, and the version in HOME menu → ABOUT.
• Pull requests are welcome. Keep the style of the code around your change, add a host test when you can, and make sure tests/run_tests.sh passes. Contributions are credited in the release notes and the manual.
• By contributing you agree that your code is released under GPL-3.0, like the rest of SLOOP.

Credits and thanks

• Felucca by Leo Kuroshita (@kurogedelic) / Hügelton Instruments — the engines, the sequencer, the editor, the installer, in 2.3 the USB audio input, the MIDI clock, the knob reading and many fixes, and in 2.4 the FM6 engine and its DX7 patch editor (Felucca 1.0 / 1.0.1). Thank you.
• @renebohne — the played-note key lights (pull request #11).
• ChanceTheMaker and keremimo — the TRS MIDI input fix (Felucca Salt) and contributions to the MIDI clock.
• Everyone who installed SLOOP, made music with it, commented, reported a bug or asked for a feature — most of 2.3 and 2.4 comes from your messages (parameter locks, DX7 patches, dotted delays, longer steps: you asked for them).
• Samples: Versilian Studios VSCO-2 CE and VCSL, Sonic Pi (all CC0). Font: Terminus (SIL OFL 1.1). Icons: Fukiai (MIT, Hügelton Instruments). PHASE engine after CrispyZebra (GPL); VOICE after klattsch (MIT); FM6: msfa from Dexed by Google Inc. and Pascal Gauthier (Apache-2.0).
• Interface ideas after teenage engineering's pocket operators and EP-133, Elektron's step entry and Akai's MPC (swing, note repeat, erase).

Licence

Code: GPL-3.0-only (see LICENSE, and LICENSING.md for the assets). No warranty. M-VAVE and FM-1 are trademarks of their owners; SLOOP is not affiliated with M-VAVE, teenage engineering, Elektron or Akai. Drum kit names describe styles, not products.