Crown Audio CTs 8200 Advanced Features and Options, CTs Multi-Channel Power Amplifiers, page

CTs Multi-Channel Power Amplifiers

5 Advanced Features

and Options

NOTE: For more information about these Crown amplifier features, please visit the Crown web- site at www.crownaudio.com.

5.1 Protection Systems

Your Crown amplifier provides extensive protection and diagnostic capabilities, including thermal level control, fault indicators, automatic high-pass filtering, DC pro- tect, AC under-/over-voltage protection, inrush limiting, and variable-speed fans.

5.1.1 Thermal Level Control (TLC)

If an amplifier channel starts to overheat, the TLC circuit will engage that channel’s input compressor. By com- pressing the input, the amplifier will not generate as much heat and will have a chance to cool down. The degree of compression is proportional to the amount of overheating. If the channel becomes too hot for safe operation even after full TLC limiting, the channel will shut off, and the Thermal Indicator for that channel will flash brightly to alert the user that a state of thermal stress or overload has cause the channel to shut down.

5.1.2 Fault

If an amplifier channel requires service, the correspond- ing Fault indicator will illuminate to alert the user of this condition. If this occurs, return the amplifier to the Crown factory or to an authorized Crown service center.

5.1.3 Fault Isolation Topology (FIT)

Crown’s new FIT (Fault Isolation Topology) design iso- lates channel-specific faults, and prevents them from affecting remaining channels. If a CTs multi-channel amp is powering multiple zones, and a channel fails, the other zones continue to operate. FIT makes the CTs 4200 and CTs 8200 the most trustworthy multi-channel amplifiers in the business!

5.1.4 35-Hz High-Pass Filter

Afixed 35-Hz (70-Hz in CTs 4200) high-pass filter per channel pair is automatically inserted when the mode switch is set to either of the constant-voltage settings. The high-pass filter corner frequency can be set to 70 Hz, or bypassed, with a service option.

5.1.5AC Under-/Over-Voltage Protection

If the AC line voltage varies out of an acceptable range, the amplifier’s power supply turns off and the blue Power LED flashes. The amplifier will turn back on when the AC line voltage returns to safe operating levels. Figure 5.1 provides voltage limits for all amplifier AC voltage con- figurations. Also, the amplifier must be run within the specified mains frequency requirements (indicated on the amplifier’s back panel label). If you are unsure of the out- put voltage of your AC mains, consult your electrician.

Models	Under-Voltage	Over-Voltage
	Limit	Limit
100VAC	90VAC	110VAC
(CTs 8200 only)
120 VAC units	108VAC	132VAC
220V/230V/	198VAC	264VAC
240V units

Figure 5.1 AC Under-Voltage and

Over-Voltage Limits for Various Amplifier

Models

5.1.6 Power Fuse

A fuse protects the amplifier from excessive AC current draw.

5.1.7 Inrush Limiting

Asoft-start circuit in the power supply minimizes the amplifier’s current draw during power-on.

5.1.8 Variable-speed Fans

Continuously variable speed fans direct the airflow through the amplifier for cooling.

5.2 Advanced Features

5.2.1 Switching Power Supply

Crown’s new 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 absorb the substantial waste that occurs when operating 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 120V/60Hz, 220V/50Hz, 230V/50Hz, 240V/50Hz, and 100V/50Hz AC mains.

5.2.2 Mode Switch

Each consecutive pair of channels has one four-position switch that selects the amplifier’s mode of operation. The switch positions are:

•Dual mode for 4 or 8 ohm operation.

•Dual mode for 70V constant-voltage opera- tion.

•Bridge-Mono mode for 8 or 16 ohm opera- tion.

•Bridge-Mono mode for 100V constant-voltage operation.

Be sure to turn off the amplifier before changing the Mode-switch setting.

5.2.3 Bridge Mode Indicator

This yellow LED indicates when the amplifier’s mode switch is set to the Bridge position. Each consecutive pair of channels has one Bridge LED.

page 14 Operation Manual