The A³ instrument, from the booth

Advice that does not fit the instrument is noise. This is the shape of A³ as of 2026-10-31, seen from the performer’s side; the full user documentation is at https://a3-audio.github.io/a3-doc/.

The parts

Devices sit on one PoE Ethernet switch and talk OSC over UDP.

  • A³ Core — the computer everything plugs into, with a multichannel audio interface. Its program, a3-core, does the audio and computes the 3D (Ambisonics) sound field for the speakers, the booth and binaural headphones. It has a portrait touch screen for setup; during a set nobody needs to touch it.

  • A³ Mixer — a 4-channel DJ mixer panel (gain, EQ, volume, PFL, FX key, AUX-Send, 3d per channel) that remote-controls Core. The same desk exists as an app, the virtual desk.

  • A³ Motion — the device with the screen. Records and plays back movement per channel and sends it to Core, so a sound moves through the room in time with the music. Per channel: two encoders, one pot and a row of pads; global keys; and a touchscreen, which is how the whole interface is operated (the encoders do one fixed job each).

  • StemDeck — up to four decks (A–D) that play tracks split into stems (drums, bass, other, vocals) and place each stem in the room themselves. Behaves like a CDJ-3000 on Pro DJ Link.

  • beat-analyzer — follows the music’s beat from the audio, or from Pro DJ Link, and gives the system its clock.

The two ways sound moves

  • Stereo channel (CDJ, turntable, any ST input): the 3d control pulls a filtered band (chosen by FREQ and Q) out of the stereo signal and moves it through the room, while the rest stays put. 0 = plain stereo; 0.5 = the band in 3D and the rest steady (the sum is the original); 1 = only the filtered band, in 3D.

  • Stems (StemDeck): a whole stem moves; no band filter is needed, because the stems are already separate. A stem at rest is steady; an action raises its 3D to full over its first beat and back over its last.

What a performer does with Motion

Picks a clip, records a movement by dragging a blob across a sphere for a set number of bars (a quarter bar up to 32), and plays it back in time; fires actions (momentary pads) for accents; loads a set that puts a clip and six actions on each of four channels. Playback follows a beat clock: INT (tap tempo), EXT (the beat-analyzer), or PIO (Pro DJ Link).

Things worth remembering when proposing a change

  • Motion runs standalone. A plain build is the full interface with mouse and touch and no panel attached. That is the default, not a degraded mode, and it is how the interface is tried and demoed. A proposal that only makes sense with a knob under the hand ignores most of its users.

  • The minimum room is four speakers, or just headphones (maintainer, 2026-10-30).

  • Clips carry movement, not sound. 3d, FREQ and Q are never recorded into clips; only actions (and later the pro-DJ’s pilot) move them (A³ decision, 2026-10-07).

  • Core asks, devices answer. Nothing is sent unasked at start-up; a device comes up by asking Core what the room is doing.

  • Cost is to be published with a crowdfunding campaign; the docs carry no prices yet.