Crest Audio Stereo Amplifier - Manual (Page 13)

Crest Audio Pro Series Power Amplifiers Page 11
Connecting Power
Professional Series power amplifier power requirements are rated at:
a) “idle”
b) 1/8th power (“typical” music conditions)
c) 1/3rd power (“continuous” music conditions)
d.) maximum rated power.
The maximum power current draw rating is limited only by the front panel circuit breaker. Consult the specifications in the
Appendices section for figures on the current that each amplifier will demand. Make sure the mains voltage is correct and is the same
as that printed on the rear of the amplifier. Damage caused by connecting the amplifier to improper AC voltage is not covered by any
warranty. Unless otherwise specified when ordered, Crest amplifiers shipped to customers are configured as follows:
North America - 120VAC / 60Hz
Europe - 230VAC / 50Hz
Asia - 220VAC / 50Hz
Australasia - 240VAC / 50Hz
South America - 120VAC / 60Hz or 220VAC / 50Hz
Japan - 100VAC / 50Hz
NOTE: Always turn off and disconnect the amplifier from mains voltage before making audio connections. Also, as an extra precau-
tion, have the attenuators turned down during power-up.
Operation Modes
Stereo Operation
For stereo (dual channel) operation, turn the amplifier off and set the mode select switch to the stereo position. In this mode, both chan-
nels operate independently of each other, with their input attenuators controlling their respective levels. Thus, a signal at Channel 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. For models 9001 and 10004, the recommended minimum nominal load impedance for stereo or parallel operation is 2
Ω
per
channel. For model 10001, the minimum is 1 ohm per channel. Note: The Model 7301 has no mode select switch; it always operates
as a dual-channel amplifier. Model 10004 has two mode select switches, one for channels A/B, and one for channels C/D.
Parallel Operation
For parallel (dual-channel/single input) operation, turn the amplifier off and set the mode switch in the parallel position; both amplifi-
er channels are then driven by the signal at Channel A’s input. No jumper wires are needed. Output connections are the same as in the
stereo mode. In the parallel mode, only Channel A’s input is active; Channel B’s is out-of-circuit. Both input attenuators remain active,
allowing you to set different levels for each channel. Power and other general performance specifications are the same as in the stereo
mode. Note: Model 7301 has no mode select switch; it always operates as a dual-channel amplifier.
Bridged Mono Operation
Both amplifier channels can be bridged together to make a very powerful single-channel monaural amplifier. Use extreme caution when
operating in the bridged mode; potentially lethal voltage may be present at the output terminals. To bridge the amplifier, set the rear
panel mode select switch to the bridge position. Apply the signal to Channel A’s input and connect the speakers across the hot outputs
(the “+” binding posts of Channels A and B).
Unlike the stereo and parallel modes, in which one side of each output is at ground, in the bridged mode both sides are hot. Channel
A’s side is in phase with the input. For proper operation, both input attenuators must be in the same position. This keeps the load bal-
anced between the channel outputs. As in the parallel mode, only Channel A’s input is active. Note: The Model 7301 cannot operate in
bridged mono mode; it always operates as a dual-channel amplifier. See the separate section on this model.
Bridged Mono Operation - Model 10004
The Model 10004 power amplifier is configured so that one or both pairs of channels can be bridged to mono. Using the rear panel
mode select switches, follow the same procedures as outlined above to bridge channels A&B together and/or C&D together.
Never try to hold the power
switch in the “ON” position if it
won’t stay there itself! Always
turn off the amplifier before
changing operating modes!