Lab.gruppen C Series 5:4X - Manual (Page 26)

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C Series C 20:8X, C 10:8X, C 10:4X and C 5:4X Operation Manual rev. 1.1.4
Operation and Performance
5.4.7 Constant voltage 70 V and 100 V systems setup and operation
When using C Series amplifiers to drive constant voltage (high-impedance) speaker systems at 70 Vrms or 100
V peak, you can in most cases simply connect the speakers to the amplifier output terminals, select the correct
VPL setting, and place the amplifier in service.
5.4.8 Output Current Peak Limiter (CPL)
The Current Peak Limiter (CPL) ensures that the amplifier will not be damaged by trying to deliver current to the
outputs exceeding the physical limitations the transistors. The CPL keeps the amplifier within the Safe Operat-
ing Area. The CPL is non-adjustable and has different limit values depending on model type. The maximum
output current values for the four C...X models are:
▸ C 20:8X, 8 Arms per channel
▸ C 10:8X, 5.6 Arms per channel
▸ C 10:4X, 8 Arms per channel
▸ C 5:4X, 5.6 Arms per channel
CPL activity is indicated by illumination of an orange LED for each channel on the front-panel. Warnings also
are shown in the DeviceControl software’s GUI.
A steadily illuminated orange CPL LED indicates a short circuit situation (or very low impedance). The output
will mute for 6 seconds before measuring the output impedance again. This will continue until the short circuit
is fixed, at which time the output will automatically un-mute. An input signal must be present to allow detection
of short circuit or low impedance conditions.
If the CPL LED is steadily illuminated orange while the
output is muted and the -4 dB signal LED is NOT on,
then the amplifier output is detecting a short circuit or
low impedance condition. The problem can be solved
by checking input and output cables and examining the state of
the loudspeaker load. If there is no short circuit present, then the
condition may be rectified by lowering the VPL or input levels.
If the CPL indicator is lit continuously, then the amplifier is delivering excessive current and is being forced into
a current limiting state (output muted).