CDJ-3000 / CDJ-3000X: the reference instrument

The CDJ is what a club DJ’s hands already know. A³ takes its interaction from the CDJ: where a habit exists there, A³ meets it rather than teaching a new one (see the booth). Facts below are paraphrased from the CDJ-3000X manual (page numbers of the German edition); the manual itself is not in this repository — get it from the manufacturer, see sources. Use it to be right, not to quote at length.

What the hands know

Tempo (p. 78)

  • The TEMPO fader’s range steps through ±6 % → ±10 % → ±16 % → WIDE on one key, with resolutions of 0.02 %, 0.05 %, 0.05 % and 0.5 %. WIDE is ±100 %; at −100 % the track stops.

  • TEMPO RESET plays at the track’s own tempo whatever the fader says.

  • Master Tempo changes speed without changing pitch (key lock). One key, lit when on.

Cue (p. 83)

  • In pause, CUE sets the cue point; during play, LOOP IN/CUE sets it. A new cue point replaces the old one.

  • CUE during play jumps back to the cue point and waits (cue standby).

  • Holding CUE and pressing PLAY carries on playing from there without a gap — a habit A³’s StemDeck copies exactly (A³ decision, 2026-10-28).

Loops (p. 86–89)

  • LOOP IN / LOOP OUT set a loop by hand; holding LOOP IN sets a 4-beat loop at the tempo.

  • Dedicated 4 BEAT LOOP and 8 BEAT LOOP keys, which in a loop halve and double its length.

  • On the touch screen, BEAT LOOP offers 1/4, 1/2, 1, 2, 4, 8, 16, 32 beats: powers of two.

  • RELOOP/EXIT leaves a loop, and pressed again re-enters it from the loop-in point.

  • Emergency loop: if the next track does not start when one ends, the player loops a beat loop on its own so the set is never interrupted by silence. During it, nothing else can be operated.

Hot cues (p. 91–92)

  • Eight hot cues, A–H, per track. A press starts playback from the point instantly.

  • A hot cue set during a loop stores the loop.

  • The key colour says what is on it: a cue point (green, or the colour set in rekordbox), a loop (orange), nothing (dark). State by light, not text.

  • A key that already holds a hot cue cannot be overwritten; it has to be deleted first — protection against a mis-hit in front of a crowd.

  • Gate cue: playback runs while the key is held and stops when it is released (a momentary pad).

Quantize (p. 95)

  • With QUANTIZE on, cue points, loop points and hot cues snap to the nearest beat, even if the press was off the beat. Hot cues, loops, reverse and slip then do not break the rhythm.

  • The beat value it snaps to is a setting. It needs a track analysed by rekordbox (a beat grid).

Beat jump / loop move (p. 96)

  • Jumps the play position by a set number of beats forward or back; inside a loop it moves the loop.

Beat Sync (p. 100–101)

  • Syncs a player’s tempo and beat position to the sync master on the Pro DJ Link network. Needs an analysed track.

  • A player becomes sync master by its MASTER key. Master moves when the master’s track changes or it is paused, when the master’s MASTER key is pressed, or when another player’s MASTER key is pressed.

  • On a synced player that is not master, the TEMPO fader no longer controls the tempo. Switch sync off and the tempo stays until the fader is moved to match it (“pickup”, the same idea as soft takeover).

  • A pitch bend on a synced player switches beat sync off and syncs only the BPM.

  • Instant Doubles: the master’s track is loaded onto another player at exactly the same position.

Pro DJ Link — see Pro DJ Link. Player numbers 1–6 on a CDJ-3000 (p. 113, Utility “PRO DJ LINK”: Player No. Auto, 1–6).

What this means for A³

  • Loop and clip lengths in powers of two, in beats below a bar and bars above. A³ Motion’s clip lengths run from a quarter bar to 32 bars.

  • Quantised by default, with an instant variant. A³ Motion starts and pauses on the next downbeat; SHIFT makes it now. That mirrors quantize on/off and gate cues.

  • Hot cue ≠ loop. An A³ action pad held is a gate (momentary); a clip is a loop you sit inside.

  • Tempo ranges: a deck should offer the CDJ’s ±6 / ±10 / ±16 / WIDE. (StemDeck shipped ±8 / ±16 / ±50 with ±8 at start; the 2026-10-08 defaults audit proposed the CDJ steps. The default range a CDJ starts in was not verified.)

  • Where the “one” is is set by hand on the jog, as on a CDJ; a deck syncs beats, not bars.

  • StemDeck behaves like a CDJ-3000 on the link — announce, claim a player number, keep-alive every 2 s, beat and status packets — so that real players and tools accept it (see Pro DJ Link).