Crown Audio S Series Advanced Features and Options, Protection Systems, Bias Servo, Fault, page

S-SeriesPower 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 Systems

S-Series amplifiers are protected against shorted, open or mismatched loads; over- loaded power supplies; excessive temperature; chain destruction phenomena; input overload damage; and high-frequency blowups. They also protect loudspeakers from input/output DC, large or dangerous DC offsets and turn-on/ turn-off transients.

4.1.1 Bias Servo

Bias servo translates the output heatsink tem- perature to controlled bias current. This pre- vents thermal runaway and holds the amplifier’s notch distortion to a minimum.

4.1.2 Fault

The amplifier will light the Fault LED on the front panel if the amplifier output stage stops operating. If this happens, take the unit to an authorized Crown Service Center.

4.1.3 Ultrasonic and Radio Fre- quency Protection

An amplifier's slew rate only needs to be large enough to deliver the maximum voltage at the highest required frequency. Higher slew rates actually let the amplifier reproduce undesirable frequencies. By design, the S-Series amplifiers have a controlled slew rate to put a frequency limit on the highest frequencies that they repro- duce. This limit occurs well above 20 kHz, so there is no audible effect on performance.

This approach protects the amplifier from radio frequencies and can even protect some sensi- tive loads (including some tweeters).

4.1.4 Drive Protection

This system temporarily removes output drive to protect the amplifier and its loads. Drive pro- tection can be activated in two situations. First, if dangerous subsonic frequencies or direct current (DC) is detected in the amplifier's out- put, drive protection will activate. The amplifier resumes normal operation when it no longer detects dangerous output. Activating this pro- tection is very unlikely, but improper source signals like infrasonic square waves or a severely clipped input signal can activate this system.

Second, the amplifier's fault protection system puts the affected channel into drive protection mode in rare situations where heavy common- mode current is detected in its output. The amplifier should never output heavy common- mode current unless its circuitry is damaged. Activating drive protection helps prevent further damage.

4.1.5 Compression

A full-time compressor is in-line with the sig- nal, reducing the risk of damage to your speak- ers.

4.1.6 Power Circuit Breaker

A front panel push button is used to reset the circuit breaker that protects the power supply.

4.1.7 Proportional-speed Fan

The speed of the cooling fan is controlled by the transformer temperature and the heatsink temperature.

4.2 Advanced Features

4.2.1 Crown SST Modules

Crown optional SST (System Solution Topolo- gies) modules were specially designed to improve the fidelity and versatility of your audio system. They feature a variety of professional signal routing and filtering capabilities, with active crossovers that allow the audio signal to be split and sent to auxiliary amplifiers. Your amplifier may have come with an SST module already factory-installed, or your choice of SST modules can be easily added to the amplifier by any authorized Crown Service Center.

For information on wiring and configuration of amplifiers equipped with an optional Crown SST crossover module, please refer to the SST Crossover Reference Manual included in your literature package.

Refer to the following descriptions for an over- view of available Crown SST crossover mod- ules. Crown plans to release additional accessory plug-in modules offering a range of advanced features and capabilities. Watch for new releases:

Operation Manual page 15