MIDI input

Connect a USB or Bluetooth MIDI controller and play ARC-24 from keys or pads. MIDI input is off by default — turn it on in Setup → MIDI.

MIDI settings are global (not saved per song). The same channel and drum mapping apply across all projects.

Enabling MIDI

Open Setup (gear icon)
Scroll to MIDI
Turn on Enable MIDI Input

USB controllers usually appear as soon as they're plugged in. For Bluetooth, tap Bluetooth MIDI to open Apple's pairing screen, then connect your device.

Screenshot setup-midi-full.webp

Setup MIDI section: Enable toggle on, Omni channel, Pad Base Note, Connected Devices list, Bluetooth MIDI row.

Connected devices

The Connected Devices list shows every MIDI source iOS reports — including virtual endpoints you didn't pair yourself.

What you might see	Meaning
Your controller name	A physical USB or Bluetooth MIDI device
Network MIDI (Session 1)	Apple's built-in Network MIDI session — not a hardware controller. It lets a Mac or another device on your network send MIDI into iOS when configured in Audio MIDI Setup. Safe to ignore if you're only using a USB/BLE controller.
No MIDI devices connected	No sources at all (unusual on iOS — you often still see Network MIDI)

ARC-24 auto-connects to all available sources while MIDI input is enabled.

MIDI channel

Setting	Behavior
Omni (default)	Accept note messages on any channel (1–16)
Channel 1–16	Only accept messages on that channel

Use a fixed channel when your controller shares a bus with other gear, or when you want one keyboard to target ARC-24 on channel 1 and leave other channels alone.

Tap quick pills 1–4 while Omni is selected, or use the stepper after picking a single channel.

What MIDI can control

Performance mode	MIDI behavior
Notes	Each key sends its MIDI pitch to the selected track with velocity. Works like tapping the pad grid — including Hold, ARP, recording, and Erase.
Drums	Consecutive MIDI notes map to kit pads from the Pad Base Note. One-shot hits with velocity. Requires a drum track.
Sampler	Same pad map as drums (16 pads). Pads layout plays that pad’s sample; Keys layout pitches the source sample from that pad (same as tapping the grid). Requires a sample track.
Chords	Not supported yet

Switch to Notes, Drums, or Sampler on the performance screen before playing from a controller.

Notes mode

Note-on plays the pitch on the selected synth track (respects track mute/solo and mixer level).
Note-off releases the note (unless Hold or ARP changes that behavior — see below).
Velocity scales loudness like pad velocity.
Recording — if the track is armed and transport is playing, MIDI notes are recorded into the loop.

Hold and ARP

With Hold on, each MIDI note-on toggles that note latched on/off (same as pad taps). Note-off is ignored.
With an ARP preset active, the first note-on on a pitch latches the phrase from that root; a second note-on on the same pitch stops the arpeggiator (same as re-tapping the root pad).

See Hold mode and Arpeggiator (ARP).

Drums mode

Drum pads are mapped from consecutive MIDI note numbers (every semitone) starting at the Pad Base Note.

Setting	Default	Example
Pad Base Note	36 (C2 in ARC labels)	Note 36 → pad 1, 37 → pad 2, 38 → pad 3, …

Use the − / + stepper in Setup to line up your controller's layout. Setup shows the full note range for the selected track's kit (e.g. a 16-pad kit needs 16 consecutive notes; a 20-pad kit needs 20).

Mapping is chromatic — white keys alone skip pads.
Only notes at or above the base note trigger pads; lower notes are ignored.
Notes past the kit size do nothing. If the base note is too high, pads above MIDI 127 are unreachable.
With Enable MIDI Input on, each drum pad shows its MIDI note name under the sample label.
Per-pad volume, pan, and pitch from Drum Settings still apply.
Recording follows the same rules as on-screen pads: transport playing + drum track armed.

See Drums performance.

Sampler mode

The sixteen sampler pads use the same Pad Base Note map as drums (pad 1 = base, pad 2 = base+1, … pad 16 = base+15).

Layout	MIDI behavior
Pads	Plays the sample on that pad (if loaded), with velocity. Empty pads are ignored.
Keys	Treats the note like tapping that Keys pad — pitches the source sample (Scale or Chromatic). Needs a Keys source assigned.

MIDI does not open Edit, Chop, Clear, Set Source, or Set Root — performance and erase only.
With MIDI enabled, each sampler pad shows its MIDI note name.
Selected track must be a sample track.

See Sampler.

Erase mode

While Erase is on and the transport is playing:

Notes — MIDI note-on begins a playhead erase hold for that pitch (same as holding a pad).
Drums — MIDI note-on erases the matching pad hit when the note maps to a valid pad.
Sampler — MIDI note-on erases matching sampler loop hits for that pad index.

Erase does not fire when arrangement playback or export is active.

See Erase mode.

When MIDI is ignored

Incoming MIDI is dropped when:

Enable MIDI Input is off
The message is on a filtered-out channel
Arrangement playback or export is running
Drums / Sampler mode but the selected track is the wrong instrument type (use Use T[N] on the instrument banner)
Chords mode (not supported yet)
Sampler while Edit, Chop, or Clear pad mode is active

Backgrounding the app stops playback and tears down MIDI until you return to the foreground.

Tips

Match your controller's MIDI channel to Setup, or leave Omni for simplicity.
Set Pad Base Note once to match your hardware (GM drums often start at 36); the same setting maps Drums and Sampler pads.
Network MIDI (Session 1) is normal on iOS — you don't need to "disconnect" it to use USB or Bluetooth.
MIDI does not change which track is selected — pick T1–T8 on the control bar first, same as on-screen performance.