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AES Interfaces: Making the Right Connections


Interoperability between different types of professional grade digital audio equipment is possible largely due to the standardization efforts of the Audio Engineering Society, or AES. The so-called “AES” standard was published by the Society in 1992 and is known officially as AES3-1992 or simply AES3.

The AES3 standard specifies a balanced interface. The cable is 110 ohm shielded twisted pair terminated in 3-pin XLR connectors – male for an output, female for an input. The voltage level is 2 to 7 volts peak to peak. Maximum recommended cable length is 100 meters.

In 1995, the Audio Engineering Society published a second standard, known officially as AES3-id-1995 or simply AES3id. This standard specifies an unbalanced interface. The cable is 75 ohm coax terminated in BNC connectors. Male connectors are used on cable ends, and female connectors are used on equipment inputs and outputs. The specified voltage level is 1 volt peak to peak. Maximum cable length is 300 meters. This standard is also documented by the Society of Motion Picture and Television Engineers as SMPTE 276M.

Formatting of the digital audio bit stream is identical for both AES3 and AES3id. It is therefore feasible to interconnect equipment with one interface type to equipment with the other interface type. In order to do this, all that is required is to make the necessary physical and electrical conversions between the two interface types.

Several years before the AES3id standard was published, Graham-Patten devised a system to transport AES formatted digital audio on coaxial cable. The company called this system DATS, which is an acronym for Digital Audio Transmission System. Graham-Patten designed this interface into a number of its products, and produced converters to allow the products to be interfaced with equipment with balanced AES3 inputs and outputs. These converters, the DATS-10 and DATS-21, continue to be available today from Graham-Patten.

The DATS-10 converts an AES3 balanced signal to an AES3id unbalanced signal. It resembles a standard 3-pin female XLR cable connector. The metal shell of the connector contains the electrical components that are required to perform the balanced to unbalanced conversion and to attenuate the signal level. A female BNC connector is provided for the AES3id connection.

The DATS-21 converts an AES3id unbalanced signal to an AES3 balanced signal. It resembles a standard 3-pin male XLR cable connector. The metal shell of the connector contains the electrical components that are required to perform the unbalanced to balanced conversion and to boost the signal level. A female BNC connector is provided for the AES3id connection.

These converters allow equipment with both types of interfaces to be easily integrated into anyprofessional digital audio system.

Graham-Patten Systems, Inc.
(530) 477-2984
Email:Graham Patten

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