User manual

AUDIO I/O AND SERIAL PORT WIRING ENG
Page 30
8.2.1 Converting between AES/EBU and S/PDIF interfaces
There are a number of differences in the electrical characteristics of AES/EBU and S/PDIF interfaces which in some
cases can render them completely incompatible. Although the audio data is the same in both AES/EBU and S/ PDIF
interfaces, they are indeed different formats, at least in their subcode. AES converted to coax is NOT S/PDIF, and
S/PDIF converted to XLR balanced is NOT AES. They are still their native format, just the transmission medium has
changed. Whether they will work in your application depends on the equipment chosen and, for proper performance,
XLR input should therefore not be used for connection to consumer equipment.
AES/EBU uses a balanced differential line based on XLR connectors and the signal levels are 5 volts. S/P-DIF
uses a coaxial unbalanced line with RCA connectors and the signal levels are around 0.5 volts. The protocol
used in AES/EBU and S/PDIF is not exactly the same and that can cause problems sometimes. The basic data
format of AES and S/P-DIF are identical. There is a bit in the channel status frame that tells which is which.
Depending upon the setting of that bit, some bits have different meanings. For example, the bits used to describe
de-emphasis in the AES/EBU protocol overlap the bits used to implement the SCMS (serial copy management
system) protocol in S/P-DIF land.
Furthermore, S/PDIF usually uses 75 ohm coaxial cable and RCA connectors. 75 ohm coaxial cable is
inexpensive, because it is the same cable as used in video transmission. AES/EBU-interface uses the well known
symmetrical connections with transformer isolation and an output impedance of 110 ohm.
18.3 DIGITAL AUDIO OUTPUT **
The digital output features two connectors: coaxial and optic. The output format is AES3/EBU
with sample rate 48KHz, 24 bit.
Please keep the tos-link connector covered while not used.
The coaxial input (on XLR) is transformer balanced, and so highly immune from external
disturbances and noise (EMI).
When fitted, the Digital Audio output is always active
. The output level is not adjustable..
** Available as an option on ST and TV version only
18.4 ANALOG AUDIO OUTPUT
The processor features XLR analog outputs electronically balanced by high-quality
buffers, capable of withstanding even low-impedance loads (600Ohm), with levels of up
to +20 dBu. Level and preemohasis are adjustable from the menu.
A reference tone (400 Hz / 0 dB) can be generated, which indicates the maximum
frequency deviation of 75KHz),