Crest Audio CPX 3800 - Manual (Page 23)

p. 23
stereo
For stereo (dual channel) operation, turn the amplifier off and set the mode
select switches on the back panel to the OUT (extended) position. In this
mode, both channels operate independently of each other with their input
attenuators controlling their respective levels. For example, a signal at chan-
nel A’s input produces an amplified signal at channel A’s output, while a signal
at channel B’s input produces an amplified signal at channel B’s output.
parallel
For parallel (dual channel/single input) operation, turn the amplifier off and
set the connector mode (Conn. Mode) switch to the parallel position by
depressing the switch. Both input connectors are then strapped together and
drive both channels with the same input signal. Because both connectors are
strapped together, either connector can be used with a patch cable to drive
the input of another amplifier. Output connections are the same as in the
Stereo Mode. In Parallel Mode, both input attenuators remain active, allow-
ing users to set different levels for each channel. Power and other general
performance specifications are the same as in the Stereo Mode.
bridged mono
Both amplifier channels can be bridged together to make a very powerful
single-channel monaural amplifier. Use extreme caution when operat-
ing in bridged mode; potentially lethal voltage may be present
at the output terminals. To bridge the amplifier, depress the rear panel
Amp Mode switch (11) to the IN position. Direct the signal to channel A’s
input and connect the speakers across pin +1 and pin +2 of the channel
A Speakon® output connector. Only channel A’s input attenuator is active
while in Bridged Mono mode. Both connectors are strapped together,
so either connector can be used with a patch cable to drive the input of
another amplifier.
Unlike the Stereo
and Parallel Modes, in
which one side of each
output is at ground, in
the Bridged Mode both
sides are hot. Pin +1 is
Channel A’s side, which
is the same polarity as
the input. The minimum
nominal load impedance
in the Bridged Mode is 4
ohms, which is equivalent
to driving both chan-
nels at 2 ohms. Driving
bridged loads of less
than 4 ohms will activate
GCL™ circuitry, result-
ing in a loss of power
and potential thermal
overload.
a
operation modes
4
When operating in the
Bridged Mode, both
attenuators must be in
the same position so
the speaker load will be
equally shared between
the channels.
a