USB 7127-7128
Professional Power Amplifiers
7127 Rear panel
16. MODE SELECTOR SWITCH
These amplifiers offer 3 modes of operation: PARALLEL, STEREO & BRIDGED. Slide the switch to one
of the three positions for you application.
• PARALLEL (MONO) INPUT - This mode allows both channels to operate in parallel with the same sig-
nal and without requiring a Y-cord. In this mode the inputs for both channels are internally connec-
ted, so that you only need to feed a signal into one of the channels. This still allows independent level
control of each channel. It also enables easy "daisy-chaining" with other amps by using the other
channel of input connectors .
(Note: Do not select this "Parallel" mode when feeding the amplifier with 2 separate signals.)
(Note: Do not use both unbalanced and balanced cables in the same set-up as that can unbalance all
the connections when daisy-chaining, resulting in hum.)
• STEREO INPUT - This is the most common mode generally used, and allows independent control of
2 separate signals such as stereo playback, main and monitor live mixes, and biamp operation (highs
in one channel and lows in the other).
• BRIDGED MONO - This mode combines the power of both channels to drive a single speaker. In this
mode the amp produces 4 times the peak power and 3 times the sustained power into a 4 or 8 ohm
speaker than each channel can deliver separately in stereo or parallel mode.
(CAUTION: In this mode the amplifier can deliver high power into a speaker. Make sure that the spea-
ker, connectors and wiring can handle this output. Note that for prolonged overdriven outputs into a
4 ohm speaker the mains fuse may blow, so care must be taken not to overload the amplifier in such
operation.)
Connect the input signal to CH-1 input for bridged mono operation.
17. VENTILATION HOLES
The fan speed is varied automatically to maintain the proper internal operating temperature.
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