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Operation Manual
CT Power Amplifiers
page 14
13 Advanced Features
13.1 Protection Systems
Your Crown amplifier provides extensive protection
and diagnostic capabilities, including thermal level
control, fault indicators, high-pass filtering, DC
protect, AC under/over voltage protection, inrush
limiting, and a convection-cooled chassis.
13.1.1 Thermal Indicator
If the amplifier becomes too hot for safe operation, the
channel that is generating too much heat will be shut
down until the temperature is reduced.
13.1.2 Fault
The amplifier will enter a Fault state if the amplifier
senses an unsafe condition. This protection is for both
internal and external faults. It is critical to check all
wiring to and from the amplifier to ensure the fault is
not caused by external conditions. Once wiring has
been verified to be correct, and the fault condition
persists, see Section 17 Service for Servicing
information.
13.1.3 High-Pass Filters
HPF’s are traditionally used in Hi-Z applications. The
Com-Tech DriveCore is a low Z amplifier but can be
used in conjunction with the XFMR 4/8 transformer
box for Hi-Z applications. If the amplifier is to be used
in a Hi-Z application, then it is very important to use
the HPF to prevent transformer saturation.
13.1.4 AC Under/Over Voltage
Protection
If the AC line voltage drops below 25% or rises above
15% of the nominal operating voltage of the amplifier,
the amplifier’s power supply turns off and the blue
Power LED flashes. The ampli fier will turn back on
when the AC line voltage returns to safe operating
levels (within ±10%).
13.1.5 Circuit Breaker
A circuit breaker located near the IEC power inlet
protects the amplifier from excessive AC current draw.
13.1.6 Convection-cooled Chassis
The DriveCore amplifiers require no fans for cooling,
providing quiet operation and optimum efficiency.
13.1.7 Auto-Standby
If amplifier does not see input signals for a period of 30
minutes, the amplifier will go into standby mode. The
amplifier will come out of standby mode once an input
signal is present. This feature is activated via DIP switch
#2 on the back of the amplifier. The amplifier will be
configured with Auto-Standby turn-on from the factory.
When the amplifier is in Standby, the Ready Indicator on
the front panel Display will flash.
13.2 Features
13.2.1 Switching Power Supply
Crown’s Switching Power Supply minimizes the
amplifier’s weight. Typical non-switching power
supplies require large, heavy transformers in order to
produce the required power at the output stage. These
transformers must be large to operate at 50 to 60 Hz
(standard AC supplied by the power company).
By contrast, switching power supplies can operate with a
much smaller (and lighter) transformer because they first
convert the AC up to a much higher frequency, thereby
reducing waste. The power supply is voltage-specific,
allowing use in regions using 100V or 240V.
13.2.2 Power Mode
Deep sleep and green mode allow the amplifier to operate
at all times with the lowest possible power level.
13.2.3 Adaptive Rail Technology (ART)
Crown has developed a voltage rail technology that
delivers power on demand. ART is at the center of CT
DriveCore’s Green mode that provides up to an additional
10% of efficiency. Through ART, the CT DriveCore is
always operating at maximum efficiency.
13.2.4 DriveCore Power Stage
Crown has worked with Texas Instruments to develop an
audio amplifier on a micro-chip. The result is DriveCore
chipset that introduces audiophile quality for an
installation amp:
-Greater than 90% Efficiency
-118dB Signal to Noise
-THD less than .05% in midband
frequencies
14 Accessories
14.1 XFMR 4/8
The ComTech DriveCore amplifier is only capable of
low Z applications. It is necessary to use an outboard
transformer for Hi-Z applications. Crown highly
recommends the use of the XFMR 4/8 transformer box.
This transformer box is designed to mate with the top
of the ComTech DriveCore Amplifiers. See XFMR data
sheet for wiring diagram.
14.2 Rack Support Ears
The ComTech DriveCore amplifier requires front and
back rack support for proper mounting. These have
been provided with the amplifier.