What Is AES50? Channel Count, Latency and Cable Limits

AES50 is the cable between a Behringer or Midas console and its stage box. One shielded Cat5e run carries 48 channels each way with a fixed, tiny delay. It is not Ethernet, even though it uses the same plug.

The short answer

• Channels: 48 in each direction at 48 kHz, 24 each way at 96 kHz, per link.
• Latency: 62.5 microseconds, which is three samples at 48 kHz. Fixed, not variable.
• Cable: shielded Cat5e with Ethercon ends, up to 100 m, per Behringer.
• Topology: point to point. One cable, one box on each end. No switches.

What it is

AES50 is an Audio Engineering Society standard for moving many channels of digital audio and a word clock over one cable. It started as SuperMAC at Sony’s Pro Audio Lab, was approved as an open, royalty-free standard in 2005, and the current revision is AES50-2011. Klark Teknik took over the patents in 2007, which is why every Behringer, Midas and Klark Teknik box speaks it and almost nothing else does.

The clock rides on the cable pairs that Fast Ethernet doesn’t use. That is the detail that matters on a stage: the console and the stage box lock to the same clock the moment the cable goes in, with no clock setting to get wrong.

What it is not

• Not a network. You can’t put an AES50 link through a switch or a router. Each port talks to exactly one other port.
• Not Dante. Dante is IP audio that routes across ordinary switches. AES50 is a dedicated link. Getting between them takes a bridge; see AES50 to Dante and back.
• Not Ultranet. Ultranet uses the same connector to feed 16 channels to personal mixers, one direction only. See Ultranet vs AES50.

Channel count in practice

An X32 Rack has two AES50 ports, A and B, so 96 channels each way in total. One S16 uses 16 of those inputs and 8 outputs; a DL32 uses 32 and 16. Stage boxes chain: the second S16 plugs into the first box’s second AES50 port and shares the same 48-channel link back to the console. Three S16s on one port would want 48 inputs, which is the whole link, so bigger stages split boxes across ports A and B.

Cable and distance

Behringer’s guidance for its stage boxes is shielded Cat5e with Ethercon-terminated ends and a maximum of 100 metres. The shield matters because the clock pairs are unprotected signal, and a cheap unshielded patch cable that works fine for a laptop can drop the link under stage lighting. Buy the cable as a snake, with the locking Ethercon shell, and treat it like any other snake: no sharp bends, no running it under a case wheel.

Preamps

AES50 carries no preamps of its own; it carries the audio the stage box’s preamps already converted. What it does carry is control. Gain, phantom and pad on an S16 or DL32 are set from the console screen over the same cable, and saved with the show file. For the preamp counts on each box, see stage boxes for IEM rigs.

Sources

• AES50 (Wikipedia, citing the AES50-2011 standard): channel counts, latency, clock, history
• Behringer S32 manual, AES50 cabling: shielded Cat5e, Ethercon, 100 m