An alternative firmware for the M-VAVE FM-1, for electroacoustic experimentation, live ambient music and sound exploration.

Install via browser · Manual · Website · Changelog

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Warning

Installing Tonitor replaces the firmware M-VAVE ships with the FM-1. It is unofficial, is not made, endorsed or supported by M-VAVE, and installing it may void any warranty that applies to your device. You install it at your own risk; read the disclaimer first.

What it is

Tonitor turns the FM-1, a small FM groovebox, into an instrument for acousmatic and electroacoustic music — sound heard for itself, its texture, its grain and its movement — and for live ambient music, dark ambient above all.

It is not a groovebox. There is no tempo, no step sequencer, no pattern, no drum kit. Instead there are six tracks of sound objects: each track has its own engine, its own sound, voices drawn from a shared pool as it needs them, and its own free loop recorder, and every sound is drawn by algorithms that aim for surprise rather than for a preset that sounds nice. You play textures, drones, gestures and their slow transformations, layer them, loop them freely out of time with each other, and shape them while they play.

The screen is made for low vision: very few words, in very large type, with high contrast, and each track in its own colour.

Highlights

• Seven sound engines, chosen per track:
  • FM — six-operator, DX7-style FM, generating sound objects: bells and gongs, spectral drones, noise, impacts, iterations, glissandi, beating spectra, sub-bass, creaks.
  • ANIMA — a lo-fi synthesizer played by a simulated hand (oscillators, FM, grains, noise, filters, folding, a phaser and a resonator), all moved by the hand's gestures.
  • CALIGULA — a restless eight-oscillator organism after the architecture of the LYRA-8, with cross-modulation, a hyper-LFO, bursts and surges, and a simulated hand on its plates.
  • RUSSOLO — noise, logic and broken buffers: sample-and-hold and dusty noise, oscillators combined bit by bit, generated buffers read with their address bits bent, chance-driven tones; crushed and sample-held like a small DAC.
  • DRUID — strings and resonant bodies after Mutable Instruments Rings: a Karplus-Strong string with dispersion, sympathetic strings, and a modal resonator, plucked, struck, bowed or rattled.
  • BAYAREA — a West Coast voice: a morphing oscillator with two FM modulators, a wavefolder, and a low-pass gate or a sustaining envelope over resonant low-passes.
  • HIVE — a swarm of seven oscillators per voice, detuned, stacked or on inharmonic partials, moved by slow LFOs and noise, through a 4-pole filter with its own envelope and a drive; melodic kinds and textural ones.
• Generative paths — lean each track's new sounds towards AMBIENT (ethereal, melodic, dark) or EXPERIMENTAL (edgier, gnarlier, more textured), or leave it OPEN.
• Six free loopers, one per track, with up to ten overdubs each, every loop with its own length.
• Envelope: attack, decay, sustain and release per track, on the ENVELOPE page, drawn on the screen.
• Latching: hold notes, press SHIFT, and they sustain as drones while you play on top.
• Per track: DJ resonant filter, granulator (dark ↔ scatter), bit/rate crush, distortion, level, pan and a send to a lush master reverb (Dattorro plate).
• Scales on the white keys (23: the seven modes, minors, pentatonics, blues, whole tone, octatonic, Hungarian minor, double harmonic, enigmatic, Prometheus, Japanese and Balinese scales), any root.
• 64 session slots in the FM-1's flash: every track, sound, loop and setting.

Installing

The easiest way is the browser installer: connect the FM-1 with a USB data cable, open the page in a desktop Chrome, Edge or Opera (they support Web MIDI with SysEx), and follow it. It finds the FM-1, checks what it runs, writes Tonitor and checks the result. Nothing is uploaded anywhere: the page talks to the FM-1 directly.

It installs over whatever the FM-1 runs now — M-VAVE's own firmware, another alternative firmware or an earlier Tonitor. Do not unplug the FM-1 while it writes.

To build and install from source instead, see Building from source.

If something goes wrong: hold OCT− while switching on for the USB rescue mode (the screen says RESCUE), then install again. Two failed starts in a row also enter it. Holding OCT− and OCT+ for five seconds enters the chip's own updater (UBOOT). If the FM-1 no longer starts at all, recovery needs FM-1-transporter.

Going back: the installer and ./install.sh install any FM-1 package; to return to M-VAVE's firmware, use M-VAVE's own updater. Apart from the update itself, Tonitor writes to the FM-1's flash only when you save a session — into a user data area that other firmwares may also use, so saving Tonitor sessions overwrites any projects another firmware left there.

Manual

Playing it

Control	What it does
FX SEL ENV LFO EDIT GLO (top row)	choose track 1 2 3 4 5 6. The chosen track's button is lit; the others glow while they sound. Held (0.8 s): copy the track, or paste the copy onto it — see Copying a track.
PRESETS knob	the chosen track's engine: FM, ANIMA, CALIGULA, RUSSOLO, DRUID, BAYAREA or HIVE, left to right. Each track keeps a sound of each engine, so turning back finds the sound it had.
SHIFT + PRESETS	in the track's view, a new sound of the family before or after on the track's engine (the family's name shows under the engine). At the first or last family, a new sound of that family again.
HOME	a new sound for the chosen track, on its engine (never the same family twice in a row). HOME lights for a moment.
SHIFT + HOME	a new sound of the same family (kind, species) as the chosen track's sound — to explore a family you like. The screen says SAME FAMILY.
OCT− / OCT+	the chosen track's octave, −3 to +3, shown at the top right of the screen (+1, −2; nothing at 0). OCT− is lit below the middle, OCT+ above.
SHIFT + OCT− / OCT+	every loop of every track down or up one step of the scale (see the loopers).
SHIFT + a track's button held + OCT− / OCT+	that track's loops only, down or up one step of the scale (TRANSP T3 +2).
the white keys	play the chosen track in the scale chosen (ARP): the first white key is the root, each white key the next note of the scale, up across all 16. Voices come from one pool of twelve shared by all the tracks: a note takes a free voice, so a track has as many as its notes need — a chord on one, a single line on another — and a new note never cuts the release of the one before it while voices are free. With the twelve all busy, a new note takes the release that has rung longest (on any track), else the oldest note held on its own track, else the oldest held anywhere. (CALIGULA and RUSSOLO are one organism a track, outside the pool.) A key lifted ends its note on the track it was played on, so a held note keeps sounding while you choose and play another track. The keys you hold on the chosen track light up.
the rightmost black key	SHIFT (lit while held). Hold white keys and press SHIFT: they latch — they keep sounding after you let go, and their keys stay lit. Hold SHIFT and press a lit key to let go of it.
the two leftmost black keys	the chosen track's generative path: the first AMBIENT, the second EXPERIMENTAL (lit while chosen; the screen says which). Pressing the lit one again goes back to OPEN. See below.
the 3rd black key from the right	the ENVELOPE page, up and down (lit while up; it acts when let go): KNOB 1–4 set the chosen track's attack, decay, sustain and release. See Envelope. With SHIFT: the chosen track's step sequencer, BRICKLAYER, on and off (the key blinks while it is on; PLAY starts it); held (0.6 s) while it is on, its page up or down. See BRICKLAYER.
the black key before SHIFT	EDIT, on and off (lit while on): KNOB 1–4 become four macros that shape the chosen track's sound. See Macros. With SHIFT: the chosen track's physics sequencer, BALLSY, on and off (EDIT blinks while it is on; PLAY starts it); held (0.6 s) while it is on, its page up or down. A short press is always EDIT. See BALLSY.
the 3rd black key	chord mode for the chosen track: held (0.6 s), on or off — CHO at the top left of the screen while on, the key lit; pressed, the next chord form (its name on the screen). See Chords.
the 4th, 5th and 6th black keys	the chosen track's loops REVERSE (played backwards), PENDULUM (forwards and backwards in turn) or RANDOM (the notes in an order drawn at random); pressed again, forwards. Lit while on. See Direction and speed.
the 7th and 8th black keys	the chosen track's loops at HALF SPEED or DOUBLE SPEED; pressed again, normal speed. Lit while on.
all black keys	play no notes. They glow dimly while off and are fully lit while on — the loop direction and speed keys only while the chosen track's loops play; SHIFT is lit only while held.
SHIFT + ARP	the chosen track's engine's PRESETS page (see Presets): there ARP held saves the track's sound into the slot chosen, ARP pressed loads it. SHIFT + ARP again, or a track button, goes back. (SHIFT + SAVE before 0.51.)
ARP	the SCALE page (ARP lit): SELECT chooses the root (C to B), ALGORITHM the scale. The root is shown very large, the scale under it; what you just turned flashes black on white. ARP again, or a track button, goes back.
REC	the chosen track's looper. Press to arm a new loop (REC flashes, the band shows ARMED and its number); the first note you play starts it (REC lights; REC and the number). Press REC again to end it: the loop is exactly as long as from that first note to this press, and it starts playing at once, round and round. Press REC again while it plays to overdub: the same again, a new loop over the others — up to 10 loops a track.
SHIFT + REC	the chosen track's loops VARY, on and off (VAR at the top right of the screen, under the octave and the battery, while on): each note they play gets a random level (from −10 dB to full) and a random length (50 ms to 1.5 s) instead of the recorded one, and now and then, at odds of its own, it is changed or joined: dropped this time round (5 %), late by 5–40 ms (25 %), an octave up or down (8 %), replaced or joined by a note that was not recorded — a step or two of the scale away, or a fifth (8 %), preceded by a grace note a step away (4 %), struck 2–4 times quickly (4 %), joined by a third or fifth above (10 %), echoed 1–4 times 120–400 ms apart, each quieter, sometimes climbing or falling a step each time (15 %); the notes of a chord are sometimes strummed 20–60 ms apart (12 %). Every note stays in the scale. The loops' pace is no longer steady either: it rises and falls slowly, and every few seconds on average it halts for a moment and resumes at once, bursts to 2–3× for a moment, grinds to a stop and snaps back, or climbs to 2–2.5× and drops suddenly (not while REC records). Applies to all its overdubs. Stored in sessions; ends when the track's loops are emptied.
REC held (1 s)	empty the chosen track's looper, all its loops: the whole screen flashes LOOP n / EMPTY.
PLAY	on BALLSY's or BRICKLAYER's page: starts or stops that sequencer (PLAY or STOP on the screen; PLAY blinks with the sequencer's key while it plays). On every other page, pressed and let go: stop the chosen track's loops, or play them again, each from its start. Held: the chosen track's loops on the white keys, to bring each in or take it out (see The loopers). PLAY is lit, steadily, while they play. SHIFT and PLAY, from any track: if any loop or sequencer plays, every loop and sequencer on every track stops (ALL STOPPED; the loops are kept); if none plays, every loop and every sequencer that is on starts, all together from their starts (ALL PLAYING). PLAY alone still starts or stops the chosen track's own.
SELECT knob	the chosen track's level: 1.5 dB a click, from OFF up to +4.5 dB. The message band says it as the knob's share of its turn, OFF and 4 % to 100 % (VOL 74 %); a track starts at 87 % (0 dB).
KNOB 1	the chosen track's DJ filter: from the middle (off), left is a resonant low-pass coming down from 20 kHz to ~35 Hz, right a resonant high-pass going up from 16 Hz to ~12 kHz; the further from the middle, the more resonant. While you turn it, and for a second after, the whole screen is its dial (in the track's colour, the mode and cutoff under it: LP 1.2 KHZ). Saved with the session.
KNOB 2	the chosen track's granulator: the middle is off (as it starts). Left towards dark ambient: long, overlapping, slowly drifting grains, pitched down now and then, darkened, fed back on themselves, sometimes frozen. Right towards scattering: short, fast grains, their timing, place, pitch and level jittered more and more, reversed, stuttered, full of holes, decimated at the far end. The further from the middle, the more grains and the less of the track. While you turn it, the whole screen is its dial (DARK 40, SCATTER 25, OFF). Saved with the session.
KNOB 3	the chosen track's crush: the middle is off (as it starts). Left takes the bit depth down from 16 to 1.5 bits (the sound coarsens, then breaks up, quiet tails gating out); right takes the sample rate down from 44.1 kHz to ~300 Hz (metallic aliasing, then a stepped buzz). Both along curves that keep the first half of the way playable; the rate glides, it does not jump. While you turn it, the whole screen is its dial (BITS 6.5, RATE 2.6K). After the granulator, before the track's limiter. Saved with the session.
KNOB 4	the chosen track's reverb send, 0–100 (40 at the start). While you turn it, the whole screen is its dial (SEND 40), as for the filter and the granulator.
SAVE	the SESSIONS page: PRESETS turns through the 64 slots (the number shown very large: red when the slot holds a session, faint grey with EMPTY under it when it does not; the session loaded says LOADED). SAVE on a saved slot loads it; on an empty slot it starts a new session there: a clean slate, as when the FM-1 is switched on — the loops and latches gone, every track on its first engine with new sounds and its settings at their defaults, the scale, reverb and transposition too (the session you were in stays saved as it was) — and the next save goes there. Either way back to playing. A track button goes back without either.
SHIFT + SAVE	GLOBAL SETUP: the FM-1's own settings, MIDI for now (see Global setup and MIDI). SAVE is lit while it is up; a track button goes back.
SAVE held (0.8 s)	save into the session loaded or chosen, at once; the whole screen flashes SAVED and the number. With none loaded or chosen yet (just after switching on), the first empty slot is offered: PRESETS chooses NO / YES, SAVE answers. On the SESSIONS page, SAVE held saves into the slot shown, whatever is loaded: an empty one asks SAVE NEW; one holding a session asks OVERWRITE? in red, on NO until PRESETS turns it to YES; SAVE answers.
SEQ	pressed again and again, three pages in turn, then back to playing (SEQ lit while one is up; a track button also goes back): the DELAY page — KNOB 1–4 are TIME (20 ms – 2 s), FEEDBACK, DAMP, MIX (see The delay); the REVERB page — SIZE, DECAY, DAMP, MIX; the MOD page — the chosen track's modulation (see Modulation).
SHIFT + SEQ	the chosen track's modulation thrown anew: both LFOs and two to four slots, at random (MOD RANDOM).
SHIFT + KNOB 3	the chosen track's distortion, 0–100 (0, off, at the start); its dial reads DISTORTION n and the amount. See The distortion.
SHIFT + KNOB 4	the chosen track's delay send, 0–100 (0 at the start); its dial reads DELAY n / SEND.
ALGORITHM knob	the chosen track's pan, left to right in 41 steps. The message band says it (PAN L 50, PAN C). Tracks start spread out: 1 in the middle, 2 half right, 3 and 4 a quarter left and right, 5 and 6 near the middle.
MIDI in (USB, and the TRS jack)	notes play the tracks by channel, CCs set their level, pan, macros, filter and sends (see Global setup and MIDI).
MASTER	the level.

Generative paths

Each track has a path that leans what HOME draws, on every engine. A path changes nothing already playing: it shapes the next sounds drawn on that track. The path's key is lit while that track is chosen.

Path	Key	Leans towards
AMBIENT	1st black key	sounds for ambient, dark ambient above all: ethereal, melodic, often melancholic. FM draws drones, beating spectra (SPECTRE), the depths (ABYSS), bells, voices (CHOIR), bowed, hollow, blooming and tidal tones, never BRUIT, IMPACT, FRICTION, SHARDS or STATIC — and plucks and mallets, never WARP, GLITCH or RUBBER; then softer attacks (a pluck or a mallet may keep its strike), long tails, darker modulators, slow LFOs, no sirens, narrower glides, often an octave down. ANIMA draws mostly HAZE, GOLDEN, VOYAGE, TIDE, CHOIR, BOWL, FOG and DRIFT, never GRIT, SHARDS, MACHINE, BITS or HOWL, with a darker tone, more space, a slower hand, long releases, no crusher. CALIGULA draws SPORE, VEIL and LITANY most, UNDERTOW, CARRION, MOTH, sometimes RUST; tuned on root, fifths, octaves, depths and unisons; slow swells, softer edges, fewer bursts and surges, a slower hand. RUSSOLO draws CHORD most, then DUST, CRACKLE, BLIPS, WALK and WANDER, never the logic kinds (NOR, XOR, RING, CASCADE, CLANG), JUMP, BEND or QUAD; clean (9–10 bits), slow attacks, long releases, calmer chance, no major chords
EXPERIMENTAL	2nd black key	sounds for electroacoustic and acousmatic music: edgier, gnarlier. FM draws bruits, frictions, shards, static, impacts, iterations, warps, glitches and rubber, brighter, bent more often (sometimes twice), never SPECTRE, CHOIR, BOWED or TIDE. ANIMA draws mostly GRIT, SWARM, SHARDS, MACHINE, BITS and HOWL, never HAZE, TIDE, CHOIR, FOG or DRIFT, and makes them wild: the sliders near their tops (FM, grain, texture, density, a quick hand), the resonance often screaming, and on most designs a crushed sample rate, folding drive, a band of noise and scattered grains, all dragged about by the hand, often a fast tremolo tearing it apart, the comb ringing hard. CALIGULA draws WIRE, THORN, HIVE and RUST most, never VEIL or LITANY; semitone clusters and tritones; sharper, more driven, more bursts and surges, a quicker hand. RUSSOLO draws NOR, XOR, CLANG, BEND and QUAD most, never WALK or CHORD; crushed to 4–9 bits, often sample-held, abrupt attacks and short releases, chance driving it hard
OPEN	neither lit	every family, kind and species alike, as before the paths. Every track starts here

Sessions keep each track's path, and the path each of its sounds was drawn on.

Macros

Press EDIT (the black key just left of SHIFT; lit while on) and the four knobs across the top stop being the filter, the granulator, the crush and the send: they become four macros that reshape the chosen track's sound, while it plays, under a held note. Every macro answers early in the turn (a quarter of the way, half the change). Each is turned from the middle, which is the sound as HOME drew it; either way transforms it. While a knob turns, the whole screen is its dial, with the macro's name for this sound and how far it is turned (+40 %, -25 %, AS DRAWN). Press EDIT again to give the knobs back.

The macros are chosen for each engine, and for some by the kind of sound:

	KNOB 1	KNOB 2	KNOB 3	KNOB 4
FM	BRIGHTNESS: the modulation index about 27 dB either way (down: towards pure sines; up: the feedback too), the carriers tilted (the higher partials up)	DETUNE: the carriers pulled apart ±40 cents and the modulators ±25 cents off them — beating, chorus, the partials off their places — or INHARMONIC for metallic and noisy families (every partial off its ratio: clangour)	SATURATION: feedback and saturation turning up; a low-pass, smoother, turning down	MOTION: the LFO's depths; turning up, a tremolo, quicker and deeper
ANIMA	TONE: every filter four octaves up or down (sharper when up), the FM brighter or darker	what the kind is about, from nothing to far more: GRAINS, NOISE, FM (the index), FORMANT (sharper when up) or DRIVE (folded hard; turned down, a pure tone: the second voice, FM, noise and grains drawn out)	RESONATOR: much wetter and ringing longer (brought in if the sound had none), or dry	MOTION: the hand four times quicker, a tremolo pulsing — or nearly still, no tremolo
CALIGULA	WAVEFORM: triangles to squares	MOD DEPTH: how deeply the pairs modulate each other	FEEDBACK (total feedback and drive) — or DELAY for SPORE, VEIL, LITANY and MOTH	TOUCHES: how busy the hand is, its touches and bursts — or GATE RATE (the gates' speed) for HIVE, MOTH and WIRE
DRUID	STRUCTURE: on a string, its dispersion (below a quarter, a buzzing bridge; above, the partials stretched, then noise in the period); on sympathetic strings, the intervals they are tuned to; on a body, how its partials are spaced, from squeezed through harmonic to bell-like	BRIGHTNESS: the exciter's low-pass and the string's or body's high-frequency loss	DAMPING: how long it rings, from ~70 ms to ~18 s to -60 dB, and above 0.95 on without decay	POSITION: where it is plucked or struck and where it is picked up — which partials sound
BAYAREA	SHAPE: the oscillator from sine through triangle and square to saw	FOLDS: the wavefolder's drive	FM: both modulators' depth	DECAY: the gate's decay, or the sustain's release, from an eighth to eight times the sound's own
HIVE	DETUNE: the swarm's spread around its places, from none to twice the sound's own	MOVEMENT: the LFOs' depth on the pitches, the levels and the filter, from none to twice	MIX: the swarm against the main oscillator — or NOISE on GROUND and AIR	CUTOFF: the filter's cutoff
RUSSOLO	the kind's first parameter (RATE, TONE, WIDTH, HISS, RATIO, SPREAD, DENSITY, SILENCE, WINDOW, STEP or DEPTH)	the kind's second parameter (CHANCE, DENSITY, WANDER, DRIFT, SUB, CLOCK, CHANGE, JUMPS or RATE)	CRUSH: fewer bits and longer sample holds, or cleaner	RANDOMNESS: how much chance drives it; above the middle, stutters too

Each track keeps the macros of each of its seven sounds. HOME draws a new sound as it comes (its macros in the middle). Sessions and presets keep the macros with the sound.

Envelope

The 3rd black key from the right opens the ENVELOPE page (the key is lit while it is up; pressed again, or a track button, closes it). It shows the amplitude envelope of the chosen track's sound as attack, decay, sustain and release, drawn and with their values. As HOME drew the sound, the page reads its own envelope and says AS DRAWN (in grey): for FM, the envelope of the loudest carrier; for CALIGULA, the average of its pairs' attacks and releases; CALIGULA and RUSSOLO have no decay or sustain stage (shown as 5 ms and 100 %).

While the page is up, the four knobs across the top set ATTACK (KNOB 1, 1 ms – 10 s), DECAY (KNOB 2, 5 ms – 10 s), SUSTAIN (KNOB 3, 0–100 %) and RELEASE (KNOB 4, 5 ms – 20 s), on logarithmic scales. The first turn starts from the values shown and replaces the sound's own amplitude envelope with this one: the attack is linear, the decay and release are exponential, the release ending 60 dB down. FM's carrier envelopes and ANIMA's envelope are then held at full; CALIGULA and RUSSOLO are kept playing through the release and then let go. The change applies from the next note; once the track's envelope is in use, turning the knobs also changes the notes that are sounding.

HOME (a new sound) or loading a preset gives the sound's own envelope back. Each track keeps an envelope for each of its seven engines. Sessions store them, copying a track copies them, presets do not.

PLAY, the sequencers and the looper

A track has one sequencer at a time: while its BALLSY is on, SHIFT + the envelope key shows NOT ALLOWED and changes nothing, and while its BRICKLAYER is on, SHIFT + EDIT does the same. The looper works beside either.

A sequencer turned on waits for PLAY. On the sequencer's page, PLAY starts and stops it, and blinks with the sequencer's key while it plays. On every other page PLAY is the looper's, as ever, lit steadily while the track's loops play: so with a sequencer playing you can put its page down (or choose the track), record loops over it from the keys (the looper records only the keys, never the sequencer's notes), and start and stop them with PLAY; bring the sequencer's page up again to start or stop the sequencer.

BALLSY

SHIFT + EDIT turns on BALLSY, a physics sequencer of bouncing balls, for the chosen track and shows its page; EDIT blinks while it is on, and SHIFT + EDIT again turns it off. The balls wait in the middle until PLAY (on their page) starts them; PLAY again holds them still where they are (their notes let go), and PLAY once more moves them on from there. Each track has its own, and they run at the same time. Holding EDIT (0.6 s) while the chosen track's balls are on puts their page down or up: with the page down the balls keep playing and the knobs, the screen and the other pages work as usual; a track button or another page also puts it down. A short press of EDIT still turns EDIT on or off.

One to eight balls move in a box on the screen. Each time a ball hits a wall, it plays a note on the track, as a key would: in the scale, with the loops' transposition and chord mode. The looper does not record them: it records only what is played on the keys. Each note's length (50 ms to 1.5 s) and level (from −10 dB to full) are drawn at random; the level applies to FM, ANIMA, DRUID, BAYAREA and HIVE (CALIGULA and RUSSOLO play at their own level). Each bounce changes the ball's angle at random by up to 12°, kept between 15° and 75° from the walls, so the paths change and every wall is reached. Each wall holds the notes of the scale, one segment per step, and the segment that is hit lights up. The pitch rises clockwise all the way round, one octave per wall:

Wall	Octave (at the start)	Direction of rising pitch
bottom	−1 (the octave below the keyboard's)	right to left
left	0 (the keyboard's)	upwards
top	+1	left to right
right	+2	downwards

While their page is up, the four knobs control them:

Knob
KNOB 1	the number of balls, 1–8; new ones start from the middle in a random direction
KNOB 2	speed, 0–100 (from 0.08 to 2.4 box widths per second)
KNOB 3	the octaves of the four walls, moved together by one octave per click, from −3…0 to +2…+5
KNOB 4	instability, 0–100 (0 at the start): each ball gets its own wind, two values that wander at random (a new aim about twice a second, followed over ~0.3 s). One scales its speed, up to 8× faster or slower at 100, so a ball can nearly stop and then rush on; the other turns it, up to half a turn per second. Occasional gusts change its direction by up to 60°. At 0 the pace is steady and the paths straight

The screen shows the box, the walls' segments in the track's colour and the balls; the line above shows the number of balls, or the value just turned. Sessions store each track's ball settings and whether they are on; copying a track copies them.

BRICKLAYER

SHIFT + the envelope key (the 3rd black key from the right) turns on BRICKLAYER, a step sequencer built a note at a time, for the chosen track, and shows its page; the key blinks while it is on, and SHIFT + the key again turns it off. It waits for PLAY (on its page), which starts it from its first step and, pressed again, stops it (its notes let go); notes can be entered whether it plays or not. Holding the envelope key (0.6 s) while it is on puts its page down or up: with the page down it keeps playing and the knobs, the screen and the other pages work as usual (a track button or another page also puts it down). A short press of the key is still the ENVELOPE page. Each track has its own.

On its page, REC is the entry, not the looper:

Gesture
REC	entry on or off (REC stays lit while it is on)
a white key, entry on	its note is added at the end of the sequence (and sounds)
SHIFT + a white key, entry on	that note is taken out, wherever it is
SHIFT + REC	the last note added is taken out
REC held 1 s	the sequence is emptied (BRICKS / EMPTY)

The notes play in the order they were added, spread over the sequence's length as evenly as possible (a Euclidean rhythm, the first note on the first step: 3 notes in 8 steps fall on steps 1, 4 and 7). Notes are kept as steps of the scale, so they follow the loops' transposition (SHIFT + OCT, and SHIFT + the track's button + OCT), the scale and the root, as latched notes do; chord mode applies to them as to keys.

Knob
KNOB 1	LENGTH: steps, from the number of notes up to 32
KNOB 2	RATE: 0.5–16 steps a second
KNOB 3	HARMONY: how often a note becomes a diad (a third or a fifth above) or a triad
KNOB 4	VARIATION: each note's level (down to −12 dB) and length (from a quarter to twice the usual) are spread at random; the pace wanders (from half to twice the rate), and now and then stops for a moment or rushes; as likely as the knob says, a note stutters (struck 2–4 times within its step), the last 2–4 steps are played again (beat repeat), a note echoes 1–3 times, quieter, or an empty step plays a quiet ghost note from the sequence. At 0: a steady level and length, a steady pace

On its page the loops' direction and speed keys (the 4th to 8th black keys) are BRICKLAYER's own, lit while on and glowing while off: REVERSE, PENDULUM (forwards and backwards in turn), RANDOM (a step drawn at random each time), HALF SPEED and DOUBLE SPEED, combined as for the loops. The step lit on the screen follows them. With the page down, the keys are the looper's again.

The screen shows the steps as cells, eight to a row (up to four rows): a note's cell filled in the track's colour, an empty one as an outline, the step being played in white. The line above shows the notes and the steps (3 IN 8), REC and the number of notes while entering, or the value just turned. Each note lasts 70 % of its step (VARIATION spreads it). Sessions store each track's sequence and settings; copying a track copies them.

Latched keys

Hold one or more white keys and press SHIFT (the rightmost black key): they latch, sounding on after you let go, and they stay lit. A key pressed while SHIFT is already held plays as usual (unless it is lit). Latches belong to the track they were made on: the keys are lit while that track is chosen, and on another track the same keys play as usual, so a drone can be left on one track while you play another. Pressing a latched key without SHIFT does nothing (it sounds already); SHIFT and the lit key lets go of it, and its note ends as a lifted key's would. Loading a session lets go of every latch. Latched notes hold voices of the shared pool: with all twelve busy, a new note can take one, even a latched one's.

Chords

With chord mode on for a track (the 3rd black key held 0.6 s; CHO at the top left of the screen, the form's abbreviation under it in grey: TRI, IN1, IN2, SU2, SU4, OPN, 4TH), each white key plays three notes: its own note and two more of the same scale, so every chord stays in the scale and its quality (major, minor, diminished) is the scale's at that degree. Pressing the 3rd black key steps through the forms (in steps of the scale from the key's note):

Form	Steps
TRIAD	0, 2, 4	root, third, fifth (the start)
INV 1	2, 4, 7	first inversion: the third at the bottom, the root an octave up
INV 2	−3, 0, 2	second inversion: the fifth below the root
SUS2	0, 1, 4	the third replaced by the second
SUS4	0, 3, 4	the third replaced by the fourth
OPEN	0, 4, 9	root, fifth, and the third an octave up
FOURTHS	0, 3, 6	stacked fourths

One chord sounds at a time on a track: a new key lets the one before go. Chords follow the loops' moves along the scale like single notes, latch with SHIFT (all three notes), are recorded by the loopers as three notes, and are kept in sessions (chord mode, its form, the chords latched); copying a track copies its chord mode.

Direction and speed

The 4th to 8th black keys set how the chosen track's loops play, all its overdubs together, each within its own length:

Key	Setting
4th black key	REVERSE: the loops play backwards — each note starts where it ended and ends where it started
5th black key	PENDULUM: forwards to the end of each loop, backwards to its start, and so on
6th black key	RANDOM: the loops play forwards, but each time the next note is due (and at the loop's end) they jump to a note of the loop drawn at random and go on from there — each note keeps its length and the time to the note that followed it when recorded; notes struck together stay together; the notes sounding are let go at each jump
7th black key	HALF SPEED: the loops take twice as long (the pitch does not change)
8th black key	DOUBLE SPEED: the loops take half as long

REVERSE, PENDULUM and RANDOM exclude each other, as do HALF and DOUBLE; pressing the lit key again returns to forwards or to normal speed. Direction and speed combine (backwards at half speed, pendulum at double, and so on). Changing the direction while a loop plays continues from where it is: a note sounding at that moment carries on and ends where its start was. An overdub recorded at half or double speed, or while the loops play backwards, is stored so that it plays back as it was played. Sessions keep the settings; copying a track copies them; emptying a track's loops (REC held) returns them to forwards and normal speed.

Copying a track

Hold a track's button until the screen flashes COPIED / TRACK n: the track is on the clipboard, and its button blinks. Choose another track and hold its button until PASTED / TRACK n: it now has the copied track's tone and loops. The clipboard is then empty: the next hold copies again. Holding the copied track's own button again copies it again (as it is now), pasting nothing.

What is copied: the tone — the engine, the sounds of all seven engines with their macros and envelopes, the filter, the granulator, the crush, the reverb send, the octave and the generative path — and all the loops, every overdub, those taken out still out, playing or stopped as they were (pasted, they start from their beginnings). The copy is taken when you hold the button: what the track does afterwards is not pasted. The track pasted onto keeps its level and pan (its place in the mix); whatever it had before is replaced, and its latched notes are let go.

The loopers

Every track has its own looper of up to ten loops, and they are all free: no tempo, no grid, no quantising — not even between a track's own loops. Each overdub is a loop of its own, as long as you made it (from its first note to REC), going round in its own length over the others, so they drift in and out of phase. Each plays back exactly what was played, to 0.73 ms. A note still held when REC closes the loop is tied over its end: it sounds on unbroken as the loop goes round, so a drone stays one long note rather than being struck again each time. The keys go on playing the track over its loops, and the loops' notes and the keys' never cut each other's notes off — but all of them share the pool's twelve voices with the other tracks, so many loops and tracks at once take voices from each other. A track's loops hold about 500 notes between them; nothing is lost when the FM-1 is switched off if the session is saved.

Bringing loops in and out. Hold PLAY (it does not start or stop anything held): the chosen track's loops appear on the white keys, the first loop — the foundation — on the leftmost, each overdub on the next, up to ten, lit while they play; the screen shows them too (in the track's colour: in; a grey frame: out). Press a key to take its loop out — its notes stop, the others go on — or to bring it back in: it comes in at once, from its start. With the loops stopped it chooses which will play: take out all but one, let go of PLAY, press PLAY, and only that one starts; then bring the others in, one by one, as the piece unfolds. Every loop is in when recorded. Sessions keep which loops are out.

Moving the loops along the scale. Hold SHIFT and press OCT+ or OCT−: every loop of every track moves one step of the chosen scale up or down — from C to D in C major, from C to D♯ in C minor pentatonic — so each loop keeps its shape within the scale. The notes sounding move at once; the screen shows how far the loops are moved (TRANSP +2, TRANSP -1, TRANSP 0), up to two octaves of the scale either way. Choosing another scale or root while they are moved walks the new one. A note outside the scale keeps its distance from the scale note below it. The white keys move with them: on a track, they play the scale moved as far as that track's loops are (all the loops' move and its own), so what you add fits what is there — and an overdub recorded while the loops are moved plays back as you played it, the others staying where they are. (USB MIDI notes are not moved.) Sessions keep how far the loops are moved.

One track's loops along the scale. Hold SHIFT, hold a track's button, and press OCT+ or OCT−: only that track's loops move (every overdub with them), a step of the scale at a time; the screen says TRANSP T3 +2. It adds to the move of all the loops, and that track's white keys and latched notes (and chords) move with it; SHIFT + OCT alone moves every track's latched notes with all the loops. The lit latched keys move along the keyboard by as many white keys, in the same direction (a latch that would leave the keyboard stays on its key, its note still moved). Holding the track's button with SHIFT down never copies it. Emptying a track's loops (REC held) takes its own move away; copying a track takes it along; sessions keep it.

The screen

From top to bottom: the track number (very large, in the track's colour), with the battery at the top right (three bars green, two green, one amber, one red when low; a white bolt on a computer's USB power, when the reading is the supply's, not the battery's -- coarse levels, not a percentage) and the track's octave to its left (+1, −2; nothing at 0), VAR under them while the loops VARY; its engine (in white), the family of its sound (in the track's colour). When something changes (NEW, OCT +1, LOOP), a black-on-white message replaces the family for a moment. While the chosen track's looper is armed the band below the engine flashes ARMED in red; while it records it shows REC, white on red. A message too long for the band at its usual size (EXPERIMENTAL) is drawn a size smaller. Under it, across the screen, the track's level meter: a bar filling from the left with the track's colour as it sounds (-48 to +6 dB), and a white mark at the level the SELECT knob sets (red at the left when the track is off). At the very bottom, the track's pan: a block in its colour on a track from left to right, with a tick at the middle.

KNOB 1 to 4 (filter, granulator, crush, reverb send) each show, while they turn and for a second after, the same full-screen dial: the knob's name and the track, an arc from 7 to 5 o'clock lit in the track's colour, a white pointer, and in large type what it does.

The REVERB page shows the title and its four values in rows, each with a bar; the row you just turned is drawn black on white for a moment.

Scales

One scale and root for the whole keyboard (and saved with the session); C major at the start. The root sits on the first white key, in the octave from C3 to B3 (each track's OCT moves it); the scale climbs from there across the 16 white keys, so a pentatonic scale spans more than three octaves.

Scale	Steps
MAJOR	0 2 4 5 7 9 11
MINOR NATURAL	0 2 3 5 7 8 10
MINOR HARMONIC	0 2 3 5 7 8 11
MINOR MELODIC	0 2 3 5 7 9 11
DORIAN	0 2 3 5 7 9 10
MINOR PENTA	0 3 5 7 10
WHOLE TONE	0 2 4 6 8 10
ENIGMATIC	0 1 4 6 8 10 11
JAPANESE IN	0 1 5 7 8 — the in (miyako-bushi) scale of the koto and shakuhachi, known for its sorrow
PHRYGIAN	0 1 3 5 7 8 10
LYDIAN	0 2 4 6 7 9 11
MIXOLYDIAN	0 2 4 5 7 9 10
LOCRIAN	0 1 3 5 6 8 10
MAJOR PENTA	0 2 4 7 9
BLUES	0 3 5 6 7 10
HUNGARIAN MINOR	0 2 3 6 7 8 11
DOUBLE HARMONIC	0 1 4 5 7 8 11 (also called Byzantine)
PHRYGIAN DOMINANT	0 1 4 5 7 8 10 — the fifth mode of the harmonic minor
JAPANESE HIRAJOSHI	0 2 3 7 8
JAPANESE IWATO	0 1 5 6 10
PELOG	0 1 3 7 8 — Balinese selisir, in equal temperament
OCTATONIC	0 1 3 4 6 7 9 10 — half step, whole step, alternating (eight notes: the 16 white keys span two octaves)
PROMETHEUS	0 2 4 6 9 10 — Scriabin's

The screen splits the longer names over its two lines (MIXO- LYDIAN, HUNGAR- IAN MINOR, OCTA- TONIC, PROME- THEUS) rather than squeezing the letters together.

MIDI notes are not quantised.

Global setup and MIDI

SHIFT + SAVE opens GLOBAL SETUP, the FM-1's own settings, kept apart from the sessions (a track button, or SHIFT + SAVE at its top level, goes back; what changed is kept when you leave). It has one section, MIDI, for now. PRESETS moves through the entries and SAVE goes into one; on a setting SAVE puts the focus on its value (a white field), PRESETS changes it and SAVE sets it, while SHIFT + SAVE leaves it as it was, or goes back a level. Each level below the top starts with BACK.

Part	Settings	At the start
IN CHAN	TRACK 1 to 6: the channel each track listens to (OFF, 1–16); AUTO: the channel that plays the chosen track	1 to 6; AUTO 16
OUT CHAN	TRACK 1 to 6: the channel each track sends on (OFF, 1–16)	1 to 6
RECEIVE	NOTES, CC (ON / OFF)	ON, ON
SEND	NOTES, CC (ON / OFF)	OFF, OFF
PORTS	USB IN, TRS IN (the 3.5 mm MIDI IN jack, Type A)	ON, ON

MIDI comes in over USB and on the TRS jack. A note plays every track whose IN channel it is on (and the chosen track on the AUTO channel), at its velocity. The CCs a track answers to, on the same channels, and sends when SEND CC is on:

CC		CC
7	level	74	filter (64 off; below, low-pass; above, high-pass)
10	pan	91	reverb send
16–19	the four macros of the track's sound	92	delay send

With SEND NOTES on, each track sends the notes it plays — from the keys, the loops, BALLSY, BRICKLAYER and MIDI — on its OUT channel, over USB. With SEND CC on, the values above go out when they change, whatever changed them. There is no MIDI clock, transport or program change: Tonitor has no tempo or patterns. The Backup page keeps the setup with the sessions and presets.

Modulation

Each track has a small modulation matrix: two LFOs and four slots that move the track's own values while it plays. The third press of SEQ opens the MOD page, in the track's colour. PRESETS goes through its six entries — LFO 1, LFO 2, then MOD A to MOD D — and KNOB 1–4 set the entry's four rows.

Entry	KNOB 1	KNOB 2	KNOB 3	KNOB 4
LFO 1, LFO 2	SHAPE: SINE, TRI, SAW UP, SAW DN, SQUARE, STEPS (a new random value each cycle), DRIFT (a smooth random wander)	RATE: 0.01 Hz (a cycle in 100 s) to 20 Hz	MODE: FREE (never restarted), NOTE (from the start at each note), ONCE (one cycle from each note, then held: an envelope)	FADE: off, or in over up to 10 s from each note
MOD A – MOD D	FROM: OFF, LFO 1, LFO 2, VELOCITY (softer notes less), KEY (the note, around C4), RANDOM (a new value each note)	TO: the sound's four macros (by their names), FILTER, GRAINS, CRUSH, DRIVE, REVERB, DELAY, LEVEL, PAN, LFO 1 RATE, LFO 2 RATE	AMOUNT: −100 to +100 of the destination's whole swing	— (the row NOW shows what the slot does at the moment)

The modulation moves the values the track already has — what the knobs set, or the macros — around where they are, and the whole track follows (every voice of it). It moves a value once a block, so it costs next to nothing. Sessions keep each track's modulation, and copying a track copies it.

SHIFT + SEQ throws the chosen track's modulation anew (MOD RANDOM): both LFOs (any shape, rate, mode and fade) and two to four slots, from any source to any destination, by amounts that may go far. It takes risks on purpose; press it again for another, or set what you like on the MOD page.

HOME draws a modulation with some sounds, by engine and family: often with the slow, sustained families of FM, HIVE, BAYAREA and DRUID (drones, pads, washes, bowed and swelling sounds) — a slow LFO on the tone, sometimes a fade in, sometimes a second, slower one wandering in the stereo field or the reverb; now and then a struck or plucked sound gets its brightness on the velocity; never ANIMA or CALIGULA, whose sounds already move by themselves. A new sound with none clears the track's modulation; a preset loaded draws the same modulation again.

Presets

Each engine has 64 presets, P1 to P64, for the sounds you want to keep and bring back on any track. Hold SHIFT and press ARP: the PRESETS page of the chosen track's engine opens, four slots a page. PRESETS turns through them; a slot holding a sound shows its number in red and the sound's name, an empty one EMPTY in grey.

• ARP held (or SAVE held) saves the track's sound into the slot chosen. Over a sound already there it asks OVERWRITE? first, on NO until PRESETS turns it to YES; ARP (or SAVE) answers.
• ARP (or SAVE) pressed loads the slot chosen into the track (which crossfades to it, as to a new sound) and goes back to playing.

A preset keeps what draws the sound again, exactly — its seed, its path and the generation of the generators that drew it — and its level: all 256 take one sector of flash, beside the sessions. Saving erases flash, which silences the audio for a moment, as a session save does.

Sessions

The FM-1 always starts with no session loaded. There are 64 slots, numbered 1–64.

A session stores in full the sound of the engine each track is on, and the others as the seed that made them and their level (the same sounds, drawn again at once), so a session usually takes one 4 KB sector of flash. A session is the whole machine: every track's engine and its seven sounds, its path, octave, level, pan, reverb send, filter, granulator (and the character it was drawn with), crush, distortion, envelopes, latched notes and loops (playing or stopped, each overdub in or out); the scale and root, the reverb, and the track chosen. They are kept in the FM-1's flash, in its user data area (saving overwrites any projects, presets or samples another firmware left there): dozens of typical sessions, at least ten even with six full loops. A session also keeps the seeds its sounds were made from, with the path and the generation of the generators that drew them: every generation is kept exactly as it was (a test checks thousands of sounds of each), so sessions and presets saved under an older Tonitor load with the same sounds after an update that brings new generators. Erasing flash silences the audio for a moment: a save uses blank flash when there is some, and the FM-1 blanks free flash by itself while nothing sounds.

Backing up. The backup page (desktop Chrome, Edge or Opera, over USB MIDI; Tonitor 0.47 or later) copies every session and both preset tables from the FM-1 to a file on the computer, and writes them back from that file — before trying another firmware, which may erase or overwrite them, and after reinstalling Tonitor. Each record is copied whole and checked (its head and body CRCs) before it replaces the one with the same number; the others on the FM-1 are kept. The FM-1 shows RESTORED and the number as each one arrives.

The granulator

Each track keeps the last half second of its own sound (at 22 kHz, 8-bit mu-law: a little grit is part of it) and plays grains out of it, after its filter. Each track's granulator has a character of its own, drawn at random when the FM-1 starts and every time a session is loaded: the intervals its grains are pitched to, how often they reverse, stutter, drop out or freeze, the shape of its scattered grains, how far its feedback and darkening go, how it drifts. The knob's position is saved with the session; the character is drawn anew. When the track's notes end, its grains ring on for about two seconds.

The distortion

Each track has a distortion, set with SHIFT + KNOB 3 (0–100; 0 is off). It comes after the track's filter, granulator, crush and limiter, and before its level, pan and sends, so the delay and the reverb receive the distorted sound.

• Two gain stages in series: the first symmetric (odd harmonics), the second asymmetric (even harmonics). The amount sets the drive into the first stage (×0.5 to ×32, up to +36 dB) and the second stage's gain and bias.
• A bias in proportion to the input's own level is added before the first stage, so the clipped wave stays asymmetric and keeps its even harmonics at any drive. At low amounts the second harmonic dominates; higher amounts add more harmonics (on a sine, up to 14 of the first 15 above −60 dB).
• The highs are raised 6 dB before the stages and lowered 6 dB after, so the mids and highs distort more than the bass. The stages run at twice the sample rate to reduce aliasing. A low-pass after them goes from 16 kHz down to 6.5 kHz as the amount goes up.
• The output level is matched to the dry signal's RMS level (measured over about 0.2 s), so turning the amount up changes the drive and the harmonics, not the loudness.

Stored in sessions and copied with the track.

The delay

A master delay, mono, placed before the reverb: each track's delay send (SHIFT + KNOB 4) feeds it, its echoes go to both sides of the master, and half of their level also goes into the reverb, so the echoes are reverberated. Its line holds 2 seconds at 22.05 kHz in 8 bits (μ-law, as the granulator's), so the repeats are slightly dark and grainy.

Parameter
TIME	20 ms to 2 s, on a logarithmic scale (shown in ms). Turning it glides the delay over about 0.1 s, so the repeats bend in pitch rather than click
FEEDBACK	how much of each repeat comes back: 0 (one repeat) to 0.95
DAMP	a low-pass in the feedback path: each repeat darker than the one before
MIX	the level of the echoes

The delay's parameters and every track's send are kept in sessions; copying a track copies its send.

The reverb

A plate after Jon Dattorro (1997): predelay, input diffusion, and a figure-of-eight tank whose two allpasses sweep slowly out of step, so the tail stays in motion and never rings. Each track sends to it after its level; the reverb's return is added to the mix before the master.

		at the start
SIZE	the room: every delay 0.5–1.25 times Dattorro's (turning it bends the tail, gently)	70
DECAY	the time to fall 60 dB, 0.4 s to about 25 s, whatever the size	65 (about 3.5 s)
DAMP	how fast the highs die in the tail	40
MIX	the reverb's return level, ×0 to ×4	50 (×1)

Track colours: 1 yellow, 2 cyan, 3 pink, 4 green, 5 orange, 6 lilac.

USB audio

Connected to a computer (or a phone or tablet that takes USB audio), the FM-1 is also a USB audio input: choose "FM-1 Tonitor" as the input in the recording program. It carries the master output, stereo, 16-bit, at 44.1 kHz (the rate the FM-1 renders at; there is no 48 kHz). The stream is taken before the MASTER knob, so the knob sets the headphones' level and not the recording's. No driver is needed; MIDI goes on over the same cable.

The engines

FM — six operators, DX7 style

The classic six-operator FM (msfa, the core of Dexed: 32 algorithms, rate/level envelopes, ratio or fixed frequencies, feedback, LFO, pitch envelope). HOME draws a patch from one of twenty-two families of sound objects (since 0.22 with their operators on the ratios they were designed with — before, a slip in the generator put nearly every ratio near an even multiple and the patches two octaves above the key; sounds saved then come back as they were):

Family	After
METAL	bells and gongs: many carriers on inharmonic ratios, the high partials dying first
DRONE	spectral drones: near-harmonic pairs detuned to beat, an index wandering over minutes
BRUIT	noises: feedback and high ratios scattered by a sample-and-hold LFO
IMPACT	struck bodies of several kinds: thuds, wooden knocks, metal hits, drum skins (membrane-like partials), debris (heavy feedback, fixed-frequency modulators); the modulators dying before the carriers; the octave sometimes moved; the pitch falling to the note on about one sound in ten
ITERATIF	iterative objects: a sound pulsed by its own LFO, square or random
GLISSE	glissandi: a pitch envelope travelling octaves, slowly
SPECTRE	a spectral arpeggio: rich tones a few cents apart whose beating lifts one harmonic after another
ABYSS	sub-bass rumble folded by feedback, breathing slowly
FRICTION	creaking: sub-audio fixed-frequency modulators and random pitch
CHOIR	vowels: carriers on the harmonics nearest two formants, a late vibrato
BOWED	a bowed string: a saw from feedback, the bow's pressure rising with the swell
HOLLOW	odd harmonics only: a dark pipe
BLOOM	a tone that opens over seconds and half closes again
TIDE	three stacks crossfading, one fading as the next swells, under a slow tide of level
SHARDS	a tone broken by random steps of pitch and chopped by a square
STATIC	ring-modulated bands from modulators nailed to audio frequencies
WIND	breath and gusts over a soft drone
PLUCK	plucked strings, bright or dark: the modulators die at once (the attack's brightness), the carriers die away, higher strings quicker
MALLET	struck bars — marimba, vibraphone, kalimba: a high modulator's knock, gone at once, the bar ringing on
WARP	anything: ratios anywhere, partials nailed to frequencies, the pitch bent about by its envelope
GLITCH	broken, mechanical sounds of several kinds: the level chopped by a square or random LFO, a crunch of heavy feedback with fixed-frequency modulators, the pitch thrown between steps by its envelope, a slow uneven wobble, and now and then a gentle sample-and-hold on the pitch
RUBBER	low ratios and the pitch bouncing in at every note: up past it, back under, onto it

Each patch is then shaped with care: modulators on high ratios turned down (their sidebands alias and scream), the brightness scaled down the keyboard so high notes are not shrill nor low ones muddy, rate scaling on the carriers. HOME draws several patches, measures each, and keeps one whose brightness suits the track's path (darker on AMBIENT, brighter on EXPERIMENTAL) and that is not of the family the track had.

Since 0.29 (generation 3) a patch may also be made plucked whatever its family, have a modulator moved to another ratio, or an operator detuned against the rest; the last five families are drawn only from then. About half the patches are then bent once more, gently (an operator detuned to beat, an envelope turned over to grow as it holds, the LFO waiting and then moving the timbre, an octave down, more feedback, a modulator's ratio moved to a neighbour, a partial nailed to a frequency). Every patch is rendered offline as it is made and given the gain that brings it to one loudness.

ANIMA — a lo-fi synthesizer played by a simulated hand

ANIMA is the lo-fi engine: each voice runs at half the sample rate (22.05 kHz, so nothing above 11 kHz), its samples drawn out to the full rate by straight lines between them. Its pitches, rates and filters are scaled to sound where they would at the full rate; what goes is the top octave of air — and half of the chip's time, so more voices sound at once.

A fixed-point port of the anima opcode from Vascular, rebuilt for the FM-1. While a key is held, a simulated finger rests on a virtual surface and drags one figure after another — orbits, figures of eight, scribbles, slow glides, now and then a flick — pressing in slow swells, and now and then lifting to land elsewhere. A ghost finger comes and goes on an irregular clock. Where the finger is, how hard it presses, how fast it moves and how long it has been down move the timbre, never the pitch.

The voice: two wavetable oscillators (24 band-limited single cycles), an FM pair, a stack of copies, a grain cloud, a filtered noise, a resonant filter, a wavetable tremolo; then the hand's chain: a downsampler, a waveshaper, a phaser, a second filter and a comb resonator tuned to the note. Each new sound is a design: which of these are in, on which waveforms, and for every parameter which gesture moves it, over what range, along what curve, plus a mod matrix of three to seven routes and Anima's eight sliders, drawn — often far from their middle. Twenty-two kinds: HAZE, VOYAGE, GLASS, BELLS, GOLDEN (Anima's own) and BREATH, GRIT, SWARM, TIDE (waves of noise over a low drone), CHOIR (vowels, a formant the hand moves), SHARDS (glass grains scattered and crushed), BOWL (a beating inharmonic hum in a ringing comb), DUST (sparse crackle over a dark drone), MACHINE (a pulsing, folded mechanism), and since 0.29 PLUCK (a plucked string: a burst through the comb tuned to the note, dying away), REED (nasal, through a formant the hand moves, a breath in it), FOG (a stack under fog, a slow phaser drifting through it), ORGAN (drawbars, a rotary tremolo, a little drive), BITS (pulses in few bits: the rate crushed and dragged about, folded), DRIFT (two saws drifting against each other, a chorus the hand moves), MURMUR (a dark cloud of noisy grains) and HOWL (noise through a resonance so sharp it whistles, swept by the hand). Every kind draws wider since 0.29 (generation 3): any of the 24 waveforms, wider intervals and ratios, a detuning, now and then a plucked envelope or a slow swell, another way for the hand to move, a pulsing tremolo, a crushed rate or a sharp resonance. The filter follows the keyboard, so low notes are not muffled nor high ones shrill; the second oscillator's interval suits the path (consonant on AMBIENT, anything on EXPERIMENTAL); and an AMBIENT sound nearly always has a resonant space to ring in.

In Vascular a design plays up to six fingers, each a voice; here a track has one voice, so the hand has one finger on the sound.

CALIGULA — an organism

The third engine, after the architecture of SOMA's LYRA-8 as Mike Moreno's LIRA-8 emulates it (BSD licence), rebuilt for the FM-1 and bent towards dark, restless textures. Eight oscillators in four pairs on two sides; each a triangle that its pair's SHARP pushes towards a square; each with a sensor and an envelope, slow (a long swell, a longer fall) or fast; each pair frequency-modulated at audio rate by its partner, the other pair of its side, a pair of the other side or the total feedback (the whole organism, saturated, fed back in). A hyper LFO of two LFOs (alone, AND, OR, XOR) opens and closes the modulation and gates chosen pairs into irregular rhythms; a short modulated delay (two lines, ~35 ms) choruses, flanges or warps it; a drive.

A CALIGULA track is played like the others: the white keys play the scale's notes, and it is silent until a key is down. A key wakes the organism at that note; a second key on top moves the whole organism to the new note at once (a snap, not a glide), and letting go of it goes back to the key still held; letting go of the last key lifts the hand and the organism rings out. It is rooted: tuned around the note played, in intervals of it (octaves, fifths, unisons and semitone clusters that beat, tritones, the depths). The hyper LFO moves timbre, never pitch: no sirens.

Nobody touches the eight plates: a simulated hand does, while a key is held. Each species has its own hand: how often it touches, how long a finger stays, how many fingers at most, its favourite plates, quick taps against long holds. The first finger stays down until the key is let go, so the sound never drops out under a held key. Around the hand the organism has a life of its own: the modulation depths and the sharpness wander, oscillators fire in bursts at irregular times, and now and then the feedback and the drive surge for a moment. A pair's envelope may be slow: a swell of seconds, a release of up to nine seconds after the key is let go.

The hand often has a phrase: two to four plates it keeps coming back to, varied now and then, often on a pulse of its own (long, short, short, longer) — so it plays like someone rather than like chance. A pair the hyper LFO's gates never close stays under it all. HOME draws a new organism from ten species, tuned on one of ten sets of intervals (pillars of octaves and fifths, semitone clusters, the depths, the harmonics, unisons, tritones, fourths, a minor seventh, open fifths, a quarter-tone cluster):

Species
SPORE	slow swells, held drones, breathing; low
THORN	sharp, deep FM, driven, bursting often
HIVE	the hyper LFO quick and gating: irregular rhythms, bursts
CARRION	the depths, heavy total feedback, the delay warped by the voices, surges
VEIL	mostly triangles, light modulation: the calmest
RUST	driven, cross-modulated, surging, sometimes rhythmic
LITANY	a slow choir: unisons and octaves beating, nothing sharp, a hand that stays
UNDERTOW	deep: heavy feedback and a warped delay pulling it under, slow surges
WIRE	high and sharp, clusters and quarter tones, a quick hand tapping, bursts
MOTH	soft triangles fluttering through the gates, on a pulse

RUSSOLO — noise, logic and broken buffers

The fourth engine re-makes the techniques of Robert Heel's Noisferatu (GPL-3.0) in fixed point, for the keys. It runs at a third of the sample rate (about 14.7 kHz) in 10-bit values, each held until the next — the grit of a small DAC — then reduces its bits and holds its samples further as the sound says.

A RUSSOLO track is played like the others and is silent until a key is down: the key opens an envelope and sets the pitch (the oscillators' frequency, the speed a buffer is read at, the rate noise is sampled at); a second key on top moves it there at once; letting go of the last key lets it fade. Like CALIGULA it is one organism a track, outside the pool of voices. HOME draws one of seventeen kinds:

Kind
HOLD	sample-and-hold noise, its rate from the key
DUST	random clicks through a low-pass that follows the key
GATES	noise opened and closed by two triangles, one wandering off the other
CRACKLE	sparse clicks ringing on short pitched decays, over hiss
NOR, XOR	two oscillators combined bit by bit
RING	two oscillators multiplied
CASCADE	squares modulating squares, a sub-octave below
CLANG	two triangles at an inharmonic ratio, XOR'd; the ratio redrawn when two clocks meet
CHUNKS	a generated buffer of noise, saw and silent chunks, read at the key's speed and rebuilt in parts
JUMP	the buffer read with jumps at random
WANDER	a window wandering through the buffer
BEND	an address bit of the buffer forced to 0 or 1, flipped or held; which and how change on a clock
QUAD	four such bendings at once, each switched on and off by chance
BLIPS	decaying triangles fired by chance on the key's harmonics
WALK	a random walk over a scale's steps from the key
CHORD	triangles on the key (minor, major, open fifths or suspended), slowly beating and swelling

Each kind has two parameters of its own, the first two macros; CRUSH and CHAOS are the other two. Its level is measured when it is drawn, and never raised so far that its loudest click could clip.

DRUID — strings and resonant bodies

The fifth engine is a fixed-point port of the resonators of Mutable Instruments Rings by Émilie Gillet (MIT licence). It plays from the shared pool of voices, like FM and ANIMA. Each kind is one of Rings' resonators and an exciter:

Resonator
String	a Karplus-Strong string: a delay line read with Hermite interpolation, damped by a short FIR filter (brightness) and a state-variable low-pass, its decay set as a time to −60 dB. Dispersion (STRUCTURE) stretches the partials with an all-pass stage, adds noise to the period near the top, or below a quarter of the range bends the bridge so the string buzzes. The output is picked up at the position along the string
Sympathetic strings	a string and three more tuned to intervals of its note (octaves, fifths, a twelfth, chosen by STRUCTURE), driven only by the first string's sound; their pickup positions drift slowly
Modal	up to 16 two-pole resonators at the partials of a bar or plate, stretched or squeezed by STRUCTURE; each partial's level depends on the position

Exciter
Pluck	Rings' plucker: a burst of noise as long as the position's share of the period, through a comb filter and a low-pass
Strike	a short pulse, longer and softer as the brightness goes down
Bow	noise for as long as the key is held, swelling in and dying away when released
Dust	random impacts for as long as the key is held

Kind	Resonator	Exciter
PLUCK	string	pluck
BOWED	string	bow
STRUCK	string, stretched partials	strike
SITAR	string, buzzing bridge	pluck
RATTLE	string	dust
HARP	sympathetic strings	pluck
DRONE	sympathetic strings	bow
BELL	modal	strike
BOWL	modal	bow
PLATE	modal	dust

AMBIENT favours BOWED, HARP, DRONE, BELL and BOWL, with long decays that carry on after the key is released; EXPERIMENTAL favours RATTLE and PLATE, with shorter decays, faster dust, extreme positions and a stronger damping when the key is released. Releasing a key damps the sound by an amount set per sound, from ringing on to stopping short. Each voice's delay lines are 16-bit and use the memory an ANIMA voice would use: a string reaches down to about 29 Hz, and sympathetic strings that would not fit their shorter lines are tuned an octave up.

BAYAREA — a West Coast voice

The sixth engine is a fixed-point port of the bayarea opcode of Vascular, contributed by its author. It plays from the shared pool of voices, like FM, ANIMA and DRUID. Each voice has:

• an oscillator that morphs from sine through triangle and square to saw (SHAPE), its frequency modulated linearly, through zero, by two sines at ratios of it (0.66 and 3.3 by default, other ratios on some sounds), each ratio wandering slightly and slowly;
• a wavefolder (FOLDS), reflecting the wave back into range;
• a 12 kHz smoothing low-pass and a trace of noise;
• either a low-pass gate, where a resonant low-pass and an amplifier are struck together by one-shot envelopes (an attack of 2–3 ms and a decay), or a sustaining envelope over two resonant low-passes (an attack while the key is held, a release when it is let go). The filters sweep from 300 Hz to the sound's peak frequency, higher for louder notes;
• a saturating output stage (tanh, then a soft clip) with its own drive;
• a bank of three resonators (508, 270 and 1153 Hz, ringing for 1–1.4 s), mixed in by the sound's amount;
• an LFO (triangle, ramp, square or random steps) that moves the shape, the folds, the two FM depths, the attack, the peak, the decay and the resonator mix, by amounts drawn with the sound.

Changed from the opcode: the square and saw are band-limited with polyBLEP instead of being summed from 44 partials (too costly for this chip), and the opcode's reverb is replaced by the track's sends to the master delay and reverb, keeping only its resonator bank.

Kind	Envelope
BONGO	gate	low peak, short decay, little folding
PLUCK	gate	brighter, square to saw, short to medium decay
CHIME	gate	the upper modulator deep, long decay, resonators
FOLDED	gate	heavy folding
SWELL	sustain	slow attack (0.3–3 s), long release
DRONE	sustain	slower attack (0.5–4 s), the lower modulator deep, long release

AMBIENT favours BONGO, CHIME, SWELL and DRONE; EXPERIMENTAL favours PLUCK and FOLDED, with more drive and folding and other FM ratios more often.

HIVE — a swarm of oscillators

The seventh engine is a port of the SWARMER machine of DigiRust, contributed by its author, extended here with inharmonic and textural kinds. It plays from the shared pool of voices. Each voice has seven oscillators, and each sound draws, for every one of them:

• its place relative to the note: the note itself, an octave or a fifth, a step of a cluster (quarter-tones, seconds), or an inharmonic partial (the modes of a free bar, a bell's partials, a stretched harmonic series, or ratios at random);
• its share of the spread that DETUNE sets (symmetric, clustered, to one side, at random, or in pairs);
• its wave, a position along sine, triangle, saw and square (neighbouring waves crossfaded);
• its level, and which of three LFOs moves its pitch and its level, and at what phase. The LFOs' rates are drawn too, from about 0.02 Hz to a few Hz depending on the kind; MOVEMENT scales their depth.

The seventh oscillator is the main one, set against the other six by MIX. Each voice also has a slow noise on every oscillator's pitch; how closely it follows the key (fully for the melodic kinds, partly or hardly at all for the textural ones); noise; a ring modulation of the first oscillator by the main one; a 4-pole filter (two state-variable filters, low-pass, band-pass or high-pass) whose cutoff follows half the key's movement and is swept by its own envelope and by the first LFO; an ADSR envelope on the level; and a drive (tanh).

Changed from DigiRust: the waves are computed as they play (the sine from its table, the triangle directly, the saw and square band-limited with polyBLEP) instead of read from band-limited tables, which would not fit in RAM here; the filter, envelopes and drive are Tonitor's own.

Kind
SUB	the main oscillator one or two octaves down, short attack; sometimes an octave up in the swarm
LEAD	brighter, short attack, resonant
STAB	short attack and decay, little or no sustain, a strong filter sweep; sometimes a fifth and an octave in the swarm
PAD	slow attack (0.2–3 s), wide detune, long release; sometimes octaves in the swarm
DRONE	slower attack, full sustain, long release (1.5–6 s); sometimes fifths and octaves stacked
WASH	the slowest attack (0.8–5 s), the longest release (3–9 s), often noise and a moving filter
CLUSTER	the oscillators at quarter-tone and semitone steps around the note, slowly beating
METAL	inharmonic partials (bar, bell, stretched or random), struck: short attack, a long decay, often a ring modulation
SPECTRA	inharmonic partials whose levels and pitches turn slowly (or shimmer), the key hardly followed: a spectrum evolving over seconds
GROUND	two octaves down, a dense inharmonic cluster with noise, a slowly moving filter, driven: rumble
AIR	filtered noise and one to seven high, drifting whistles, band-pass or high-pass, the filter swept: wind
TIDES	the oscillators gliding apart and back by up to five semitones on slow LFOs, sometimes on inharmonic partials

CLUSTER, METAL, SPECTRA, GROUND, AIR and TIDES are meant for non-melodic, textural use. On GROUND and AIR the third macro is NOISE (the noise's level) instead of MIX.

AMBIENT favours PAD, DRONE, WASH, SPECTRA and TIDES, and makes the LFOs slower and the sound darker, the attacks longer; EXPERIMENTAL favours STAB, CLUSTER, METAL, GROUND and AIR, and adds more noise to the pitches, more drive and, sometimes, a ring modulation.

Building from source

Once:

./setup.sh

It makes a Python environment in .venv (Pillow, mido, python-rtmidi), downloads JieLi's Linux toolchain to ~/.jieli/toolchain, and fetches the three files of the JieLi AC79 SDK the package needs into ~/fw-AC79_AIoT_SDK. On macOS the toolchain runs in Docker, so Docker Desktop must be running to build. ./setup.sh --font also fetches Atkinson Hyperlegible (the Braille Institute's typeface for low vision), for smoother large type than the default Terminus.

Then, with the FM-1 connected by USB and switched on:

./install.sh

It builds build/tonitor.fwsc and installs it over USB-MIDI. ./install.sh --info tells what the connected FM-1 runs; ./build.sh only builds.

Testing without the FM-1

tests/run_tests.sh

needs only clang, Python and (for the browser installer) Node. It checks the firmware for anything the chip cannot run (it has no FPU and no compiler runtime), then runs the real DSP, sound generators, mixer, loopers, sessions and screen code on the computer, and the browser installer against a simulated FM-1:

• build/sounds/ — WAVs of every engine, family and path, and mix.wav, the six tracks entering one after another;
• build/screens/ — the screen in its states, as PNGs.

How it is built

firmware/src/tonitor.c is the single compilation unit: fm.c (FM, around msfa's fm6_core.c), anima.c (ANIMA), cal.c (CALIGULA), russolo.c (RUSSOLO), druid.c (DRUID), bayarea.c (BAYAREA), hive.c (HIVE), gran.c (the granulator), reverb.c, layers.c (the six tracks, the loopers, the mix; each block the voices, the organisms and the master effects are dealt to the FM-1's two cores, audio_worker.h and hal/fm1_multicore.h), ui.c (panel and screen), sessions.c, gfx.c, dsp.h (fixed-point helpers), main.c (boot, interrupts). Based on Felucca and earlier open FM-1 firmware work: firmware/hal/, firmware/loader/, usb.c, ota.c, recovery.c, lcd.c, libc.c, the build checks and the installer. The website and the browser installer are in docs/ (served by GitHub Pages); tools/make_site.py builds its pages from site/ (home, install), this README (the manual) and CHANGELOG.md and publishes build/tonitor.fwsc for the installer.

Licence

• The firmware is free software under the GNU General Public License, version 3 only (GPL-3.0-only, LICENSE): it is a work based on GPL-3.0 code (see LICENSING.md). The browser installer (docs/js/fm1ota.js), a port of Felucca's installer, is GPL-3.0 too.
• The website, the logo and the documentation written for Tonitor (docs/ except docs/js/fm1ota.js and the firmware package, and this README's text) are under the MIT licence (LICENSES/MIT.txt).
• Third-party parts keep their own licences: msfa (Apache-2.0), the LIRA-8 architecture (BSD 3-clause), Noisferatu's techniques (GPL-3.0), Rings (MIT), the fonts (SIL OFL 1.1), the JieLi SDK files placed in the package (Apache-2.0).

LICENSING.md lists every file and its licence.

Credits

Tonitor is by Nuno Zimas. It stands on the work of others:

• Felucca by Leo Kuroshita / Hügelton Instruments — the hardware track, USB stack, update loader, rescue mode and installer that made an FM-1 firmware possible at all.
• msfa by Google Inc. and Pascal Gauthier (Apache-2.0), from Dexed, in Felucca's integer port — the FM.
• ANIMA is ported from the anima opcode of Vascular.
• CALIGULA follows the architecture of LIRA-8 by Miguel Moreno (BSD), an emulation of SOMA Laboratory's LYRA-8.
• RUSSOLO re-makes, in fixed point, the techniques of Noisferatu by Robert Heel (GPL-3.0).
• BAYAREA is ported from the bayarea opcode of Vascular.
• HIVE is ported from the SWARMER machine of DigiRust.
• DRUID is a fixed-point port of the resonators of Mutable Instruments Rings by Émilie Gillet (MIT).
• Atkinson Hyperlegible by the Braille Institute (SIL OFL 1.1) and Terminus (SIL OFL 1.1).

M-VAVE and FM-1 are trademarks of their owner, used here only to say which device Tonitor runs on.

Disclaimer

Tonitor is an unofficial firmware. It is not made, endorsed, approved or supported by M-VAVE or by the maker of the FM-1, and it is not affiliated with them.

Installing it replaces the device's original firmware and may void any warranty that applies to your FM-1, if any applies at all; check the terms of your warranty before installing. Installing any firmware carries a risk: an interrupted or failed update can leave the device unable to start until it is recovered (see Installing), and saving sessions overwrites data that other firmwares may keep in the same flash area.

The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and non-infringement. In no event shall the authors or contributors be liable for any claim, damages or other liability — including damage to your device, loss of data, or loss of the use of the device — arising from, out of or in connection with the software, its installation or its use. You install and use it entirely at your own risk. See also sections 15 and 16 of the GPL.