Operation Manual; 13.1 Protection Systems; 13.1.1 Thermal Indicator- Page 14

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.