L-ACOUSTICS LA15a 115V Manual V1.0 27/01/2003
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6.1.2 UNBALANCED INPUTS
To connect an unbalanced source, tie pin 3 (ring on TRS jack) to the shield of the connector. Note: if you
leave pin 3 disconnected, you will lose 6 dB.
A better method for using unbalanced sources is shown in Figure 8. This is similar to the connection for
balanced lines, but pin 3 is connected to the shield at the source. The hum and noise rejection for the
cable is equivalent to that for a balanced line. To minimize hum, use balanced inputs whenever possible.
Figure 8: Unbalanced Line Connection
Figure 9: Balanced Line with Unbalanced
Equipment
6.2 CONNECTING SPEAKERS
Speaker connections are made via the two
Neutrik® NL4FC Speakon
connectors. The Speakon
connector is designed for high power speaker connections and assures correct polarity, locks securely in
place and prevents from shock hazard.
The LA15a power amplifier Speakon connectors are wired in the following manner:
Channel A/B
Channel C/D
Pin +1
Channel A+
Channel C+
Pin -1
Channel A-
Channel C-
Pin +2
Channel B+
Channel D+
Pin -2
Channel B-
Channel D-
Since the Channel A/B Speakon is bi-wired, it is possible to access channels A and B on a single
connector (similarly, the Channel C/D Speakon provides access to channels C and D). This is useful
for bridged or bi-amped operation. For bi-amped operation, be careful to ensure that Channel A or B
outputs are correctly assigned to the LF or HF component of your active loudspeaker system. As
standard, L-ACOUSTICS active 2-way loudspeakers are cabled as follows: LF +/- = 1+/1- (Ch A) ;
HF +/- = 2+/2- (Ch B). The same convention holds for the Channel C/D output connector, i.e., LF
+/- = 1+/1- (Ch C) ; HF +/- = 2+/2- (Ch D). Pay attention to loudspeaker polarity: loudspeakers
connected out of phase degrade sound quality and may be damaged as a consequence.
Figure 10: Loudspeaker Connection Details
Channel A and B (or C and D) connected
via one Speakon (for quad or bi-amp
applications)
Bridged mono connection via Channel A/B (or C/D)
output connector (pins 1+/2-) to loudspeaker (+/-)
