L-Acoustics LA48A, Руководство пользователя

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L-ACOUSTICS LA48a Manual V1.0 27/01/2003 17
7.1.2 TANDEM MODE
In tandem mode both Channel A and B inputs are linked and receive the same signal. Channel B to A
linking is performed by physically connecting from the Ch A LINK connector (male XLR) to the Ch B
INPUT connector (Neutrik® Combo jack). Both Channel A and B level attenuators are active, allowing
you to set different levels for each channel.
Note: only the inputs are connected in parallel and this is NOT a parallel output mode.
Never
connect either output terminal to ground or in parallel.
7.1.3 BRIDGED MONO MODE
Figure 12: Bridged mono cabling
Bridged mono mode is used to deliver both channels' power to a
single load. The nominal impedance of the load must be more
than 4 ohms.
The input signal is applied to Channel A and then linked to the
Channel B input by physically connecting from the Ch A LINK
connector (male XLR) to the Ch B INPUT connector (Neutrik®
Combo jack). Both Channel A and B level attenuators must be at
the same position and it is recommended that they are operated
in the 0 dB (full) position.
Connect the loudspeaker as shown and always use the Channel
A output connector.
7.1.4 BRIDGED MONO MODE FEATURES
Bridged mono mode combines the power of both channels into one speaker. This results in twice the
voltage swing, four times the peak power and just less than three times the full power of a single
channel.
One way to understand the load and power from the amplifier’s perspective in bridged mode is that it
is zero voltage at the center of the voice-coil winding. This is because the coil is driven with positive
voltage at one pole and an equivalent negative voltage at the other pole. So, if an 8 ohm load is
connected in bridged mode, one channel shares one 4 ohm part of the load and the other channel
shares the other 4 ohm part. The power into 4 ohms from an LA48a (MLS at 0 dB) is 2300 W.
Therefore, the total bridged power into the 8 ohm load will be 2 x 2300 = 4600W.
7.2 OPERATING PRECAUTIONS
Never connect either Channel A or B output terminals to ground or to some other output
or input terminal (see also warnings in Section 2.4).
For normal two-channel operation, connect each speaker load across the output channel’s positive
and negative terminals.
Pay attention to speaker polarity - loudspeakers connected out of
polarity degrade sound quality and may be damaged as a consequence.
WARNING: To prevent electrical shock, do not operate the amplifier with any of
the conductor portion of the loudspeaker cable exposed.