Networking & Protocols
AES/EBU, short for Audio Engineering Society/European Broadcasting Union, is a professional digital audio interface standard that transmits two channels of PCM audio over balanced 110-ohm cable using XLR connectors. It is the industry standard for reliable digital interconnection in studios and broadcast facilities.
The AES/EBU digital audio standard, formally known as AES3, was developed jointly by the Audio Engineering Society and the European Broadcasting Union in 1985. It defines a method for carrying digital audio data between professional equipment such as converters, recorders, mixing consoles, and processors. The interface transmits two channels of linear PCM audio within a single data stream, along with embedded clock information, metadata, and status bits.
Physically, AES/EBU uses a three-pin XLR connector and balanced 110-ohm twisted-pair cable, which allows long cable runs of up to 100 metres with excellent noise rejection. The signal voltage is typically 5 volts peak-to-peak, using differential transmission to minimise interference. The format supports sample rates from 32 kHz up to 192 kHz and word lengths of up to 24 bits, although extensions allow higher-resolution transmission when required.
Each AES/EBU frame contains two subframes (one for each channel), synchronisation preambles, and embedded clock data. This allows devices to extract timing information directly from the signal, simplifying connections by removing the need for a separate clock line in many cases.
A consumer variant of AES/EBU, known as S/PDIF, uses the same data structure but operates over unbalanced 75-ohm coaxial or optical cable with lower voltage levels. AES/EBU remains the professional choice because of its robust electrical design, resistance to jitter, and suitability for complex studio installations.
