Manual

TRIO turns the M-VAVE FM-1 into a jazz rhythm section that listens. Play chords on the FM-1's keys or on a MIDI keyboard or digital piano, by cable or over Bluetooth, and a walking bass and a drummer play along with you. Both are small neural networks running on the FM-1 itself. The bass learned from FiloBass, 48 transcribed walking-bass lines from jazz records. The drummer learned from JazzSAMBA, studio recordings of jazz standards. TRIO works out each chord as you play it. Once your chords come round again, it learns the tune's form and knows what comes next. Play the bass a walking line of your own, and it learns from you: from then on it walks more the way you do.

1Install

Try it first: the emulator runs the same code in the browser, with sound. Play it with the mouse, the computer keyboard, or a MIDI keyboard plugged into the computer. Chrome or Edge asks once to allow MIDI.

Install from the browser: in Chrome or Edge, connect the FM-1 by USB, open the installer and press Install. The browser asks once to allow MIDI: allow it. Don't unplug the cable while it writes. It takes about a minute.

Install from a terminal: download trio-VERSION.fwsc from the releases, then, in a clone of the repository, python3 base/tools/fm1_install.py trio-VERSION.fwsc (it needs Python's mido and python-rtmidi).

Back to the stock firmware: the installer's last section writes M-VAVE's own firmware back. An FM-1 that doesn't start can be recovered too. For details, see felucca-bsp's tools/fm1_rescue.sh.

2Quick start

1. Press PLAY. The band counts a bar in (the screen counts 4, 3, 2, 1).
2. Play a chord, with its root as the lowest note: for example C, E♭, G, B♭ for Cm7. The bass and the drums start on the next beat.
3. Play each new chord a little before its bar, up to about an eighth note early, as a pianist does. The bass then lands on the new chord's root with you.
4. Keep going round the tune. After the chords have come round once, the screen says FORM 8 BARS (or however long your tune is), and NEXT shows what the band expects next.
5. Press PLAY again to stop.

TEMPO (K1) sets the speed: TRIO keeps its own time, so follow the band.

3The screen

4Controls

5How the band listens

Chords. TRIO listens to the notes you hold, or have just played, and names the chord: major 7, dominant 7, minor 7, half-diminished, diminished, 7sus or augmented, on any root. Two notes are enough. Play the root as the lowest note at each change: TRIO recognises rooted chords almost every time (97 to 98% in its tests). Rootless voicings are ambiguous: B♭, D, F, A is B♭maj7, and also Gm7 without its G. TRIO then guesses, and is right only about one time in five.

Timing. A chord played up to about an eighth note before a beat counts for that beat, and the bass lands on it. A chord played on the beat comes too late for the bass on that beat, because a bass player decides a moment ahead. The bass plays the old chord for that beat and follows on the next. Once TRIO knows the form, it plays the change on the beat even when you play it exactly on the beat.

The form. TRIO keeps every chord with its beat. Once the chords come round again, for example the second time through Autumn Leaves' A section, it knows the form: 8, 12, 16 or 32 bars, whatever the tune is. From then on:

• The bass walks toward each change before it comes, as a bass player who knows the tune does.
• Stop playing, and the band keeps going round the form on its own. Take a solo with your right hand, or listen.
• Play a different chord (a substitution, a new section) and the band goes with you. That one chord makes TRIO drop the form. It finds the form again once your chords repeat.
• Hold a chord across a change and the band moves on with the form. To keep the band on your chord, play it again.

Press REC to start a new tune: TRIO forgets the form and the chords.

6The feel

7Teaching the bass

TRIO's bass can learn from you. Play it a walking line, and from then on it walks more the way you do: your notes on the changes, your approach notes, your pickups.

1. Play the tune's chords round until the screen says FORM 8 BARS (or however long your tune is), then let go. The band keeps going round the form.
2. Press EDIT. The screen says TEACH BASS, and TEACHING in the header. TRIO's bass stops, and you are the bass: your single notes from E1 to G3 sound on the upright, and TRIO doesn't hear them as chords. On the FM-1's keys, press OCT− twice first: the keys then run from F1 to G3.
3. Walk a line, a note a beat, for a chorus or two. A note on the swung eighth after a beat is a pickup into the next, and TRIO learns those too. The screen counts the bars of YOUR LINE. TRIO keeps the last 32.
4. Press EDIT again, or STOP. The screen says LEARNING, and LEARNED YOUR LINE a second or so later. The bass walks again, the way you taught it, and TAUGHT shows beside its note.

How closely it follows you is FREEDOM (K2). At 0 the bass plays your line almost note for note on the same chords: 93% of the beats in TRIO's tests. At 50, where TRIO starts, about half the beats. At 100 it only leans your way. Before you teach it, it plays your note on about one beat in five.

What it learns. Your note for each place in a tune: the chord, the next chord and how far off it is, the beat in the bar, and how long since the change. It learns the tune you teach it on most, but how you walk carries over: taught on Autumn Leaves, it also walks a blues more your way, about half as much. A new lesson largely replaces the one before. To teach it in two (ARP: TWO), play in two: notes on 1 and 3, held through 2 and 4.

Chords while you teach. From E1 to G3 is your line. Play chords from A♭3 up, with the root as their lowest note, or let the form carry the band.

From the first bar. While the band is stopped, press EDIT (the screen says PRESS PLAY), then PLAY. You teach from the first bar, over your own chords from A♭3 up.

Forget. Hold EDIT for 1.5 seconds: the bass goes back to how it was trained (BASS AS TRAINED).

Keep it. Press SAVE: what the bass learned comes back the next time the FM-1 starts.

If the screen says NOTHING LEARNED, the lesson had fewer than eight notes the bass could have played there. STILL LEARNING: TRIO is learning the line before; press EDIT again in a moment.

8The mix

Press GLO for the mix page:

Press GLO again for the band page.

9Saving

Press SAVE to keep every setting: the tempo, freedom, drums, swing, feel, the mix, the piano's sound, the octave and whether Bluetooth is on, and what the bass has learned from you (see Teaching the bass). They come back the next time the FM-1 starts. The form isn't saved: each time you start, TRIO learns the tune afresh.

10MIDI and audio

MIDI comes in over USB, the TRS jack and Bluetooth: notes on any channel, and the sustain pedal (controller 64) for TRIO's piano. A MIDI keyboard or a digital piano plays TRIO as the FM-1's keys do, with all ten fingers. Turn the piano's sound off on the mix page (PRESET) if the keyboard sounds by itself.

• USB: from a computer, TRIO is a MIDI device named "TRIO FM-1". A keyboard plugged into the computer reaches it through your DAW, or through a MIDI routing utility.
• TRS: the FM-1's MIDI in jack, with a TRS-to-DIN adapter, takes a keyboard's MIDI out directly.
• Bluetooth: a digital piano or a keyboard with Bluetooth MIDI connects to the FM-1 directly, with no cable. A computer, an iPad or an iPhone can connect too.

Over the USB cable the FM-1 is also a sound card: a computer can record the trio (an input named "TRIO FM-1").

Connecting a Bluetooth piano or keyboard

1. Switch on the piano's Bluetooth MIDI, so that it advertises (some pianos call this pairing mode). If a phone or a tablet is connected to the piano, disconnect it there first: a piano usually takes one Bluetooth MIDI connection at a time.
2. Press SEL. The Bluetooth page opens, and TRIO looks for MIDI devices. When it finds one, the screen shows its name.
3. If TRIO finds more than one, turn ALGORITHM to pick yours. ALGO 2/3 means the second of three.
4. Press SEL again. The screen says CONNECTING, then CONNECTED, and DEV lights in the header.
5. Press GLO to go back to the band page, and play.

A digital piano sounds by itself: turn TRIO's piano off on the mix page (PRESET), so that you hear one piano.

To disconnect, press SEL on the Bluetooth page. If the piano goes out of range or switches itself off, the screen says DEVICE LOST, and TRIO lets go of any notes it was holding. TRIO doesn't connect again by itself: on the Bluetooth page, wait for the piano's name, then press SEL.

TRIO finds devices that advertise Bluetooth MIDI. A piano whose Bluetooth only plays audio (music from a phone through its speakers) can't connect.

Connecting a computer, an iPad or an iPhone

Over Bluetooth, the FM-1 advertises as "FM-1". On a Mac, open Audio MIDI Setup, choose Window > Show MIDI Studio, click the Bluetooth button, then Connect next to FM-1. On an iPad or an iPhone, connect from a music app's Bluetooth MIDI settings. BLE lights in the header while it's connected. A computer and a piano can be connected at the same time.

Bluetooth on or off

Bluetooth is on when TRIO starts. To switch it off, open the Bluetooth page (SEL) and turn PRESET: the screen says BLUETOOTH OFF, and the FM-1 stops advertising and drops its connections. Turn PRESET again to switch it back on. Press SAVE to keep the choice for the next time the FM-1 starts.

If the FM-1 started with Bluetooth off, switching it on starts the radio, and the FM-1's sound stops for about a second while the radio starts. So TRIO switches it on only while the band is stopped: during a tune, the screen says STOP FIRST.

The emulator shows the Bluetooth page with a stand-in device named BLE MIDI. It can't reach real Bluetooth devices.

11The screen reader

TRIO tells a screen reader what's on its screen, through the FM-1 Screen Reader. When the reader starts listening, it hears whether the band is playing, the chord, the tempo, the feel and the form, whether you're teaching the bass or it has learned from you, and whether Bluetooth is off or what's connected over it. After that, it hears each change as you make it.

12Troubleshooting

No sound: turn MASTER up. The band plays only after PLAY. The piano sounds only with PIANO ON.

The bass is late on the changes: play each chord a little earlier, up to an eighth note before its beat. Or play the tune round once: once the form is learned, the bass is on time.

The wrong chord shows: play the root as the lowest note, and three or four notes of the chord.

TRIO hears the wrong chords while I teach the bass: your notes from E1 to G3 are the bass line, not chords. Play the chords from A♭3 up, with the root as the lowest note, or play the tune round first and teach over the form.

The bass doesn't play my line after teaching: turn FREEDOM (K2) down. At 0 it follows you most closely.

LATE n in the header: the networks missed n beats. This shouldn't happen. Please report it with what you were doing.

The Bluetooth page doesn't find the piano: check that the piano's Bluetooth MIDI is on, and that no phone or tablet is connected to it. Bring it closer. If the page says Bluetooth is off, turn PRESET.

DEVICE LOST or NO ANSWER: the piano went out of range, switched itself off, or didn't answer. Switch it on, then connect again from the Bluetooth page.

The installer doesn't find the FM-1: use Chrome or Edge, allow MIDI when asked, and close other programs that use the FM-1's MIDI port.

The FM-1 doesn't start after an install: after two failed starts it waits in the chip's update mode. Put the stock firmware back, then install again. For details, see felucca-bsp's tools/fm1_rescue.sh.

13How it works

Four networks run on the FM-1's chip. Together they hold 110,000 weights, stored as 8-bit numbers.

The bass decides each note 40 ms before its beat; the drummer plays half a bar ahead. When you teach the bass, it learns on the FM-1 itself. While you play, it listens to your line beat by beat, as the bass network would have heard its own. Then it adjusts the network's last layer, the 3,500 weights that choose the note and the pickup, in about a second, and keeps the rest as trained. The sound is synthesised on the FM-1: an electric piano, an upright bass, a drum kit and a room. The bass is built from measurements of real upright pizzicato in FiloBass's recordings: each partial's level and decay, by register, and the finger's attack. Everything together uses about 40% of the chip's time (estimated from the code's instruction counts).

TRIO is built on fm1-base by Charles Vestal, and felucca-bsp by Leo Kuroshita, Hügelton Instruments. The bass learned from FiloBass (Riley and Dixon, ISMIR 2023; CC BY 4.0). The drummer learned from JazzSAMBA (Copyright (c) 2026 Phillip Long and contributors). See CREDITS.md.

M-VAVE and FM-1 are trademarks of their owners. TRIO is not affiliated with M-VAVE.