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Operation Manual
CTs Power Amplifi ers
page 42
NOTE: For more information about these Crown
amplifi er features, please visit the Crown
web site at www.crownaudio.com.
5.1 Protection Systems
Your Crown amplifi er provides extensive protection and
diagnostic capabilities, including thermal level control,
fault indicators, automatic high-pass fi ltering, DC pro tect,
AC under-/over-voltage protection, inrush limiting, and
variable-speed fans.
5.1.1 Thermal Level Control (TLC)
If an amplifi er channel starts to overheat, the TLC circuit
will engage that channel’s input compressor. By
com pressing the input, the amplifi er 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
fl ash 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 amplifi er channel requires service, the correspond-
ing Fault indicator will illuminate to alert the user of this
condition. If this occurs, return the amplifi er 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-specifi c 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 amplifi ers
in the business!
5.1.4 35-Hz High-Pass Filter
A fi xed 35-Hz (70-Hz in CTs 4200) high-pass fi lter per
channel pair is automatically inserted when the mode
switch is set to either of the constant-voltage settings. The
high-pass fi lter 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 amplifi er’s power supply turns off and the blue Power
LED fl ashes. The amplifi er will turn back on when the AC
line voltage returns to safe operating levels. Figure 5.1
provides voltage limits for all amplifi er AC voltage
con fi gurations. Also, the amplifi er must be run within the
specifi ed mains frequency requirements (indicated on the
amplifi er’s back panel label). If you are unsure of the
out put voltage of your AC mains, consult your electrician.
Models
Under-Voltage
Limit
Over-Voltage
Limit
100VAC
(CTs 8200 only)
90VAC 110VAC
120 VAC units 108VAC 132VAC
220V/230V/
240V units
198VAC 264VAC
5.1.6 Power Fuse
A fuse protects the amplifi er from excessive AC current
draw.
5.1.7 Inrush Limiting
A soft-start circuit in the power supply minimizes the
amplifi er’s current draw during power-on.
5.1.8 Variable-speed Fans
Continuously variable speed fans direct the airfl ow
through the amplifi er for cooling.
5.2 Advanced Features
5.2.1 Switching Power Supply
Crown’s new Switching Power Supply minimizes the
amplifi er’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 fi rst
convert the AC up to a much higher frequency, thereby
reducing waste.
The power supply is voltage-specifi c, 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 amplifi er’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 amplifi er before changing
the Mode-switch setting.
5.2.3 Bridge Mode Indicator
This yellow LED indicates when the amplifi er’s mode
switch is set to the Bridge position. Each consecutive pair
of channels has one Bridge LED.
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5 Advanced Features
and Options
Figure 5.1 AC Under-Voltage and
Over-Voltage Limits for Various Amplifi er
Models