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Operation Manual
CTs Multi-Channel Power Amplifiers
page 14
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
A fixed 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.
5.1.5 AC 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.
5.1.6 Power Fuse
A fuse protects the amplifier from excessive AC current
draw.
5.1.7 Inrush Limiting
A soft-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.
Models
Under-Voltage
Limit
Over-Voltage
Limit
100-120 VAC
units
90VAC 132VAC
220V/230V/
240V units
198VAC 264VAC
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.
5 Advanced Features
and Options
Figure 5.1 AC Under-Voltage and
Over-Voltage Limits for Various Amplifier Models