Lab.gruppen PLM 20000Q - Manual (Page 76)

70
Back Panel Interface
PLM Series Operation Manual rev 1.2.3
8.2.4 Iso-Float Electronic Balancing
The analog input electronic balancing circuits use the Lake Iso-Float system.
The Iso-Float technology combines the benefits of transformer-coupled isolation with the advantages of
clean, direct-coupled inputs. The audio converters are galvanically isolated, and not connected to the main
ground. High-quality transformers and opto-isolators create a barrier between the device and possible
grounding aberrations from the outside electrical environment.
Iso-Float settings are adjustable via the front panel menu or the Lake Controller software.
8.3 AES3 Digital I/O
8.3.1 AES3 XLR Connector
AES3 digital audio input is via an XLR3F connector, which is directly paralleled to the adjacent XLR3M AES3
Link connector. Wiring of this connector follows the same standard as for analog XLR connections as shown
section 8.2.2.
AES/EBU
INPUT 1-2 LINK 1-2
Figure 8-15: AES3 XLR Input and Link Connectors
Figure 8-12 on page 69 shows the only possible method of wiring; there is no equivalent of an unbalanced
connection in the digital domain.
The AES3 signal format carries two channels of audio and associated data on a single cable/connector.
Selection of Ch 1 or Ch 2 is performed within the digital processing section of the PLM and is controlled
from the menu system. Please refer to section 7.11.3.1 for further details.
The AES3 Link connector may be used to daisy-chain the inputs of multiple PLMs together. Unlike daisy-
chaining of analog inputs, attention must be paid to line termination. When daisy-chaining PLMs together,
only the last PLM in the chain should be set to TERMINATED. All other PLMs should be set to UNTERMI-
NATED. Please refer to section 7.11.3.2 for further details.
As with balanced analog audio, there is a finite limit to how many PLMs may have their AES3 inputs daisy-
chained together. The practical limit will be determined by cable type and length as well as the output circuit
of the driving source. It may be necessary to employ an AES3 line driver or distribution amplifier to achieve
reliable results in some situations.