Quick Answer / Summary: Use a balanced 110 ohm AES/EBU cable with BNC connectors, or 75 ohm coax with BNC, to link AES3 digital outputs and inputs. The standard allows up to 10 meters at 48 kHz sampling and up to 200 meters at 32 kHz. Do not substitute a microphone cable or an unbalanced pair: the signal is a fast digital stream, not an audio voltage.
An AES cable carries a digital audio signal, not a traditional analog one. It connects the AES/EBU digital outputs of a mixer, outboard unit, or broadcast console to another digital device, using BNC connectors and a balanced coaxial-style pair. This guide covers what the cable carries, which cabling to use, and the length limits that actually matter.
What an AES Cable Carries
AES3, the standard behind the AES and EBU digital audio formats, encodes two channels of digital audio into a differential data stream sent over a single balanced pair. The cable itself does not need to be expensive, but it must behave like a controlled-impedance line. That is why AES runs are usually coaxial-style pairs rather than the open construction of a typical microphone cable.
AES3 and EBU Are the Same Thing
AES3 is the American standard, EBU the European broadcast equivalent, and the two are electrically identical. A cable sold as AES, EBU, or AMR all serves the same purpose. You will see both labels on the same product, and on the same port of the same unit, which confirms they are interchangeable.
The BNC Connector
AES ports are almost always BNC, a bayonet-locking connector that resists being pulled loose on a working stage. BNC is also the connector for 75 ohm video and RF cabling, so a BNC-to-BNC cable is easy to source. The locking action matters more for AES than for video because a dropped digital stream is immediate and total.
110 Ohm versus 75 Ohm Cabling
AES3 was specified for a balanced 110 ohm pair, which is why dedicated AES cable is sold at that impedance. In practice, the digital signal tolerates 75 ohm coaxial cable well enough that most installations simply use it, and the difference in real-world performance is small for runs kept within the length limits.
Why 110 Ohm Is the Specification
The 110 ohm balanced pair gives the differential signal a defined impedance and a good margin against reflections at the data rates used in professional audio. If you are building a permanent installation and want to stay closest to the letter of the standard, 110 ohm AES cable is the right purchase.
When 75 Ohm Coax Is Fine
75 ohm coax with BNC on both ends is the common pragmatic choice. It is cheaper, easier to find, and the connector is identical. For runs within the limits below, the impedance mismatch between 75 and 110 ohm does not degrade the data, which is why so much working AES plant is built on ordinary coax.
Length Limits That Actually Matter
AES3 specifies maximum cable lengths, and those limits are the number people need when planning a run. At the standard 48 kHz sampling rate, a compliant run is 10 meters. At 32 kHz, the same cabling carries the signal up to 200 meters, which is how long building runs become possible without a repeater.
The 10 Metre Rule at 48 kHz
If the source and destination sample at 44.1 or 48 kHz, keep the run to 10 meters. Going longer is not always fatal, but you are outside the specification and each extra meter of poor cabling or a bad connector raises the risk of dropped data, which arrives as digital dropouts or complete silence.
Longer Runs at Lower Rates
For runs to 200 meters, use 32 kHz sampling over 75 ohm coax, as the standard allows. Many broadcast and installed-audio systems deliberately run at lower rates or use digital extenders when the distance grows, because the data stream, not the cable, is what breaks first.
How AES Differs from a Standard XLR Cable
Both use locking connectors and balanced construction, so they are easy to mix up. The difference is fundamental: an XLR microphone cable carries an analog voltage that degrades gently with noise, while an AES cable carries a digital stream that either arrives intact or not at all.
Analog Voltage versus Data Stream
On XLR, a noisy run adds hiss you can hear. On AES, a degraded run causes bit errors; the receiver either corrects them or loses the data, and the audible result is clicks, dropouts, or nothing. That makes cabling discipline more important, not less, for AES runs.
Labels and Colours
There is no mandatory colour code for AES cable, though grey and white jackets are common in the trade. The safest identification is the port: look for the label AES, EBU, or digital on the unit, and keep AES runs visually distinct from analog XLR runs at the patch bay.
AES/EBU Cabling Options
| Cable | Impedance | Max at 48 kHz | Max at 32 kHz | Notes |
|---|
| Dedicated AES/EBU pair | 110 ohm | 10 m | 200 m | Closest to the standard |
| Coax with BNC ends | 75 ohm | 10 m | 200 m | Common pragmatic choice |
| Reused video coax | 75 ohm | 10 m | 200 m | Fine within limits, label it |
| Microphone cable, XLR | unspecified | not recommended | not recommended | Wrong construction for data |
Practical Applications
Typical installs: linking the digital outputs of a live-sound desk to a recorder or second desk, patching broadcast console frames together, connecting an outboard digital effect with AES I/O into a mix, and running a single pair between adjacent control rooms. Where a run exceeds 10 meters at 48 kHz, plan a different sampling rate, a repeater, or a different routing technology.
Frequently Asked Questions
What is an AES cable used for?
It carries the AES3/EBU digital audio stream between devices with BNC digital ports, such as mixers, recorders, and outboard gear. It is the professional digital link inside much modern audio equipment.
Is AES the same as EBU?
Yes. AES3 (AES, United States), EBU (European broadcast), and AMR all describe the same balanced digital audio standard over the same BNC ports, so the cables are interchangeable.
Can I use a regular BNC or microphone cable for AES?
Use 75 ohm BNC coax or 110 ohm AES cable. Do not use a microphone cable: its open construction is not designed for the data stream and risks dropouts.
How long can an AES cable run be?
Up to 10 meters at 48 kHz sampling, and up to 200 meters at 32 kHz over 75 ohm coax, as the AES3 standard specifies.
Why does my AES connection drop out?
Check the length against the sampling rate, reseat both BNC locks, and inspect the cable. Bit errors from a marginal run show up as clicks or silence, not gradual noise.
