Lab.gruppen PLM 20000Q - Manual (Page 98)

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Application Guide
PLM Series Operation Manual rev 1.2.3
10.6 Digital Audio Connections
Whenever possible, it is preferable to connect a digital rather that analog input signal to the device. This is
particularly relevant if the source signal is already in the digital domain, such as the source from a digital
mixing console or digital distribution system. The primary cause of signal distortion and signal delay (latency)
is the digital-to-analog and analog-to-digital conversion process. Therefore, using digital inputs normally
provides higher quality audio with lower latency.
Two types of digital audio inputs are available: Dante networked multi-channel digital audio, and 2-channel
digital audio via the AES3. Dante-based system configurations and interconnections are explained in a
separate document, the Lake Network Configuration Guide.
The information in this section is supplied for users unfamiliar with AES3. Users already familiar with AES3
will find that the device conforms to established conventions.
10.6.1 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 8.3 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.
10.6.2 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.