Aes/Ebu Digital Audio Cabling - L-Acoustics LA8 User Manual

LA8 AMPLIFIED CONTROLLER
USER MANUAL
VERS ION 5.0
Balanced cables
Symmetrical (balanced) shielded cables are highly recommended as balanced signals are less sensitive to AC hum
and radio interference.
Unbalanced lines may add noise especially over long cable runs.
3.4.3

AES/EBU digital audio cabling

Both AES/EBU XLR connectors on the LA8 are transformer balanced and wired a ccording to IEC 268.
The 3-point female XLR input connector (IN) is provided for the amplifier to receive one AES/EBU (AES3) or coaxial
S/PDIF (IEC 60958 Type II) signal.
In a daisy-chain layout the 3-point male XLR connector (LINK) feeds the input signals to the next unit in the signal chain
(see Figure 10). The LINK connector is electronically buffered to allow daisy-chaining any number of amplified
controllers. It also features a failsafe relay to ensure wiring continuity in case of amplified controller shutdown (see
Figure 11).
Cables for AES/EBU digital audio
The quality required for the XLR cables will depend on the cable length and the signal sampling frequency. As a
starting point, a standard balanced microphone cable of maximum length of 50 m (150 ft) can be used to
transport a signal of maximum sampling frequency of 48 kHz. Higher sampling frequencies may require reducing
the cable length since the signal attenuation in cables increases with the sampling frequency.
As AES/EBU certified cables provide smaller attenuation/length ratio, it is highly recommended to use them in
installations requiring long cable runs or high sampling frequency signals.
It is recommended to use single cuts of cable. Using several pieces will reduce performances.
In case an amplified controller shutdowns, the failsafe relay makes a passive connection between the AES/EBU
IN port and the LINK port to maintain continuity. However the signal is no longer refreshed for the next
amplified controller, so that the input cable and the link cable must be considered as a unique input cable with
regard to the maximum supported length.
In case of transmission losses, try to reduce the sampling frequency of the digital audio source. Moreover, as a
general rule, avoid using sources rated beyond 96 kHz as the maximum possible cable length will be reduced
while the additional information will anyway be cancelled by SRC to 96 kHz.
LA 8_U M_E N_5 .0
Figure 9: Analog input panel wiring
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