Lake LM Series Operation Manual page 63

Application Guide
9.3.1 AES3 Digital Audio
The original AES/EBU digital audio interface standard was developed by the Audio Engineering Society in
conjunction with the European Broadcast Union. Originally published in 1985, it was revised in 1992 and
2003, and in its current iteration it is properly designated the AES3 standard.
AES3 is a serial transmission format for linearly represented (uncompressed) digital audio data. It describes
a method for carrying two channels of periodically sampled and uniformly quantized audio signals on a single
twisted-pair cable.
The data format allows for auxiliary data which can be used for information on signal characteristics as
well as the sampled audio data. The physical interconnection, as defined by IEC 60958 Type I, specifies
three-conductor 110-ohm twisted pair cabling terminated by an XLR connector. Please refer to section 7.2
for wiring details.
AES3 provides for multiple sampling rates and resolutions of up to 24 bits; this device accepts sample rates
from 44.1 to 192 kHz.
9.3.2 System Latency and Delay Compensation
All types of digital audio processing inherently involves a small processing delay referred to as latency. If the
processing chain does not involve analog-to-digital or digital-to-analog conversion, the amount of latency is
usually very small and often may be disregarded.
However, in complex systems involving multiple digital audio components and connections, enough delay
may be generated to cause audio phasing problems. Therefore, the lowest latency is always preferred, and
it is always important to consider system latency delays when calculating and adjusting overall delay for
time-aligning multiple loudspeaker systems.
9.3.3 External Signal Distribution Hardware
9.3.3.1 Distribution Amplifiers
Dedicated distribution amplifiers for AES3 signals are available from several manufacturers. The most com-
mon format is one input and six outputs. Digital distribution amplifiers are designed to refresh or reconstruct
the signal as well making up for line losses.
One type of distribution amplifier is a simple repeater, which restores the waveform shape and brings the
signal amplitude back up the required level. Some distribution amplifiers also offer a re-clocking feature,
which also re-times the signal to prevent signal degradation from clocking errors known as jitter.
Distribution amplifiers that offer re-clocking often make the feature optional as using re-clocking can intro-
duce small additional amounts of latency, so should not be used unless necessary.
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Lake LM Series Operation Manual Rev 1.3.5