Crown Audio D-45 Protection, Options 4.2.1 Bridge-MonoOption, Input-SensitivityOption, page

D Series Power Amplifiers

4 Advanced Features and Options

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.

Operation Manual page 13