Crown Audio S Series - Manual (Page 15)

page 15
S-Series Power Amplifiers
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 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:
4 Advanced Features
and Options