Installation manual

Model DMA

™

8 Installation Manual Installation

2-4

2.5 Digital Audio Sources

The DMA8 accepts a wide range of digital audio sources including:

• High-definition video server, player, or receiver

• Professional digital video tape recorder (VTR)

• Digital satellite or cable television receiver

• DVD player

• Terrestrial digital television broadcast

• CD player

A range of digital audio formats are also accepted by the DMA8 including:

• Dolby

Digital (consumer, non-film-based)

• Dolby E

• PCM (digital stereo audio)

All of these sources and formats use one of the following three methods to package

the digital data into a physical connection.

Professional Interface Standards for Digital Audio

There are two professional interface formats used for digital audio: AES/EBU and

AES3. These formats stream the same digital data and professional audio header

information over copper conductor links, but use different types of conductors and

connectors.

AES/EBU uses a balanced connection (two conductors plus shield) with a

characteristic input impedance of 110Ω, nominal peak-to-peak signal level of 5 V,

and most commonly, XLR connectors. AES3 uses an unbalanced connection (one

signal conductor plus shield) with a characteristic input impedance of 75Ω, peak-to-

peak signal level of 1 V, and BNC (“push and twist”) connectors.

Professional digital audio equipment usually uses the AES/EBU format because

balanced operation yields superior noise immunity, as it does with analog audio

signals, and because XLR connectors have been standard on analog professional

audio equipment.

Professional video equipment usually uses the AES3 variation of this interface, with

BNC connectors. Like the use of XLR connectors on pro audio equipment, the

adoption of BNC connectors for the audio on professional video equipment stems

from their existing use for the video signal. Also, the unbalanced AES3 signal can

connect to more than one piece of equipment with the loop-through connectors that

are available on some devices. Lastly, it is robust for long cable runs.