Internal Settings - Crown D-45 Reference Manual

D-45 / D-75A Power Amplifiers
Appendix A
A.1 Internal Settings
From the factory, your amplifier is configured for dual
(stereo) operation and an input sensitivity of 26 dB
gain. You may optionally configure the unit for higher-
power, single-channel, bridge-mono operation. Also,
the unit can optionally be set for an input sensitivity of
0.775 volts. To configure the unit for bridge-mono op-
eration or 0.775 volt input sensitivity, the chassis of the
unit must be opened.
WARNING: Risk of electric shock! Turn off the am-
plifier and disconnect its power cord from the AC
mains before opening the amplifier chassis.
CAUTION: Only a qualified technician should at-
tempt to change the amplifier's internal settings.
A.1.1 Opening the Amplifier Chassis
Before undertaking this procedure, please read Ap-
pendix A.1.2 and A.1.3 to help determine whether you
Fig. A.1 Main Circuit Board (Component Side)—Jumper and Resistor
Locations for Input Sensitivity and Dual/Mono Modes
need to alter the amplifier's internal settings, and
whether you want to handle these procedures your-
self.
1. Turn the amplifier off and disconnect its power
cord from the power receptacle.
2. Remove the six screws that hold the top cover in
place. (There are three screws on each side of
the unit.)
3. Remove the nine screws that fasten the bottom
cover to the chassis. This will expose both sides
of the main circuit board.
A.1.2 26 dB Gain vs. 0.775 Volt Input Sensitivity
For most applications, the amplifier's default setting of
26 dB gain will be ideal. With this default setting, full
output power is achieved with an input signal of
0.632 volts for the D-45 , and 0.837 volts for the D-75A .
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