L-Acoustics LA-RAK User Manual page 33

6.7.2 External cabling
With digital audio, routing of the signals is achieved in a convenient and flexible manner through external cabling, by
using the patch panel on the front of the LA-PANEL AES3 . Two examples are given in Figure 26 and Figure 27.
Up to six digital audio signals can be routed from an AES/EBU digital audio source (mixing console or EQ device) to the
LA-PANEL AES3 via three XLR3 cables, each one conveying two channels.
Provided the internal cabling is correct (see [6.7.1]), each pair of signals can be routed in a daisy-chain layout, by cabling
the corresponding LINK connector of the LA-PANEL AES3 to another IN connector of the same LA-PANEL AES3 (for
internal daisy-chaining), or to an IN connector of another LA-PANEL AES3 (for external daisy-chaining). It allows
modular routing layouts.
Here is important information about 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
IMPORTANT
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.
 The LA-AES3 has been tested with up to 305 m/1000 ft of 3 models of AES/EBU rated cables:
Belden® 1696A, Klotz Cables® OT234H, and Sommer Cable® SC BINARY 234 (single cuts, digital
source signal running at Fs = 48 kHz).
 Using several cuts of cables will decrease 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.
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