CLX (DJ Sync)

CLX is an open protocol for streaming real-time DJ deck state over the network — playhead position, BPM, beat number, EQ levels, and mixer faders. Arkestra receives it on UDP port 3650.

Two things come out of it. The master deck can drive Arkestra’s tempo, and every value CLX reports becomes a mapping source, so the playhead, the EQ, or the crossfader can drive any parameter in the project.

Enabling the receiver

Open the External Input panel in the right sidebar (antenna icon), switch to the CLX tab and turn on Enabled.

The receiver is off until you enable it, because starting it is what triggers the macOS local network permission prompt. Once running, the status row reads Listening on 3650. The port is fixed by the CLX specification and cannot be changed.

Arkestra also announces itself on port 7000 while the receiver is on. Senders that stream to one machine at a time use this to find you, so leave the receiver enabled before starting playback. The recommended multicast group (239.0.0.1) is joined automatically.

The Sender row shows the state the DJ software reports. While it reads Disconnected, CLX will not drive the tempo.

Choosing the master deck

Master Deck decides which deck drives the tempo.

Setting	Behaviour
Follow Active	Uses whichever deck the mixer reports as active, so the tempo moves with the mix.
Deck A–Deck D	Pins the tempo to one deck regardless of what the mixer says.

A deck only drives the tempo while it is sending packets and has a track loaded. If it goes quiet for two seconds, Arkestra falls back to the next available clock.

Tempo sync order

Arkestra has several possible tempo sources and only one can own the tempo at a time. The order is fixed, and the Tempo Sync Order section of the CLX panel lists it with a dot next to whichever source is currently winning:

1. CLX
2. MIDI Clock
3. Ableton Link
4. Auto BPM — tempo only
5. Rhythm Analyzer — tempo only

The highest source that is actually receiving data owns the tempo. The last two are marked tempo only: they estimate a BPM but have no sense of where a beat begins, so they set the rate while Arkestra’s own clock keeps the timing.

CLX never changes the Ableton Link session tempo. Other apps on your Link network keep their own tempo, even while Arkestra is following the decks.

Bar phase

CLX is the only sync source that knows where the bar starts. Its deck packets carry a beat number from 1 to 4, so beat 1 in Arkestra lines up with beat 1 in the DJ’s track. Ableton Link and MIDI Clock have no equivalent, so with those the bar begins wherever the clock happened to start.

This matters for anything that runs a pattern over a bar — a four-step sequencer, or an LFO set to a 1-bar rate.

Mapping deck values to parameters

Right-click any parameter → CLX. The mapping editor appears in the inspector with a deck selector and a field menu.

Per deck:

Field	Range
Position	Playhead through the track, start to end
BPM	The deck’s tempo across Arkestra’s 20–300 range
EQ Low, EQ Mid, EQ High	The mixer’s EQ gain for that deck
Pitch	Playback rate, centred so an untouched pitch fader sits at the middle
Upfader	That deck’s channel fader
Beat Phase	Ramps 0 to 1 across each beat
Bar Phase	Ramps 0 to 1 across each bar, reset on the real downbeat
Playing	On while the deck is playing

From the Mixer selector:

Field	Range
Crossfader	Crossfader position
Active Deck	The active deck spread across the range

The editor shows the bound channel’s live value, so you can confirm a mapping is receiving before you rely on it.

Note

CLX does not send a play/pause flag. Arkestra infers Playing from the playhead moving between packets, so a paused deck reads as stopped because its position stops changing.

Testing without DJ software

CLX senders are not something you can install alongside Arkestra, which makes mappings awkward to build before a show. The Simulator section of the CLX panel generates synthetic deck data so you can set everything up offline.

Turn on Run Simulator with the receiver enabled. It plays Deck A at 128 BPM and Deck B at 174, sweeps the crossfader over 20 seconds, flips the active deck halfway through so Follow Active has something to follow, and pauses Deck B briefly on each cycle so Playing changes state. Decks C and D stay silent.

Everything runs through the normal network path, so what you set up against the simulator behaves the same against real DJ software.

Related

• Ableton Link → — zero-config tempo sync with DAWs and other apps
• MIDI → — MIDI Clock and controller mapping
• Art-Net (DMX) → — lighting desk input