Advanced Features And Options; Protection; Options; Bridge-Mono Option - Crown D Series Operation Manual

D Series Power Amplifiers
4 Advanced Features
and Options
Operation Manual
NOTE: For detailed information about
these Crown amplifier features, please
consult the Crown Amplifier Application
Guide, available on the Crown website
at www.crownaudio.com.

4.1 Protection

Your amplifier is protected against all common
hazards that plague high-power amplifiers,
including shorted, open or mismatched loads;
overloaded power supplies, chain destruction
phenomena, input overload and high-frequency
blowups.
Protection against shorted and mismatched
loads is provided by an instantaneous limiter
that automatically limits current to the maxi-
mum safe value for the output transistors. With
a loudspeaker, you can tell the amplifier has
activated load protection because it causes
audible distortion. The noise might be com-
pared to crossover notch distortion or a snap-
ping sound, depending on the load
characteristics. Loudspeaker systems with
impedances of 4 ohms or higher should not
activate the protection system.
All voltage amplification circuitry is designed to
limit current. So in the extremely unlikely event
of a device failure, the amplifier will prevent fur-
ther damage. The input stages are protected
from overload damage by series resistors. The
unit also features a controlled slew rate and a
V-I limiter that protect the amplifier from high-
frequency (RF) blowups.

4.2 Options

4.2.1 Bridge-Mono Option

Your amplifier is factory-set for dual (stereo)
operation. As an option, you may have the unit
configured for higher-power, single-channel,
bridge-mono operation. If you want the bridge-
mono modification, take the unit to an autho-
rized Crown Service Center.
IMPORTANT: Critical differences
between dual and mono wiring are
described in Section 2.6.2.

4.2.2 Input-Sensitivity Option

The input sensitivity of your amplifier is fac-
tory-set to 26 dB gain. As an option, the unit
can be set to an input sensitivity of 0.775 volt
by an authorized Crown Service center.
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.
Some applications may require the gain struc-
ture to be calculated based on a sensitivity of
0.775 volts. And although the 26 dB gain set-
ting provides a sensitivity for each amplifier
that is very near 0.775 volts, the 0.775-volt
sensitivity setting is provided for applications
that demand this sensitivity with a high level of
precision.
A Crown Service Center can activate the 0.775
volt input sensitivity without voiding the war-
ranty.
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