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CAMCO USER MANUAL
VORTEX POWER AMP SERIES
P.18
4.4 Power Amp Protection Systems
4.4.1 Clip Limiter
If the power amp is overdriven, the clip detection circuit triggers the micro-
processor. The processor reduces input signal level by controlling the DAC.
The strategy is implemented in software. For sinusoidal signals the
microprocessor limits the input signal level with the result that the non-linear
distortion factor never exceeds 1 %.
The clip limiter can work on each channel independently (except in mono-
operation).
To disable the Clip Limiter, see 4.2.3, Limiter Switch.
4.4.2 Under Impedance Limiter
As a result of incorrectly connected or defective loads, under impedance or
even short circuits may be presented to one or both power amp channels. In
order to detect an under impedance, the microprocessor calculates the result-
ant impedance. If an impedance of less than 1.33 ohms/channel is detected, the
microprocessor limits the signal to the power amp until a subsequent
measurement indicates that impedance has risen to a safe level. Whenever the
under impedance limiter is active, the corresponding channel’s power LED is
turned off. (See 6.0, Trouble Shooting)
4.4.3 Speaker Protect Limiter
Whenever the Safe Operation Mode (SOA) protection of the power amp
switches back the current rail there could be a small clipping at the output;
but the microprocessor is also triggered by this protection and will reduce the
signal level immediately to minimise the effect.
User can decide either to use speaker protect or not. When you use this amp
for low frequencies (SUB bass / bass) and you want to squeeze the absolute
maximum out of it, switch Speaker Protect off. For all other applications (e.g.
Full Range) it’s recommended to switch Speaker Protect on.
4.4.4 SOA Protection
Whenever the power transistors leave their Safe Operation Area (SOA), the
SOA-protection in stereo mode switches back the current rail of the respective
power stage. In mono modes the rails of both channels are switched back.
4.4.5 DC Protection
Each output of the power amp is constantly monitored for persistent DC
voltage levels. If the 3 V thresholds are exceeded at any of the outputs, the
channel at that output will be automatically disconnected. The microprocessor
performs a sophisticated strategy to locate the cause of DC. If short-term DC is
detected, the amplier will recover and continue to operate. DC can be located
in the Output stage, Driver stage or at the input of the amplier.
Output stage
When DC is located in either output stage, the amp stops the main SMPS
and mutes the amp where DC was detected. The On-LEDs will show a
different ash sequence. (See 6.0, Trouble Shooting)
Driver stage
When DC is located in the driver stage only the defective channel’s output
stage and DCA are muted. The other channel still works. The On-LED of the
defective channel will start the ash sequence. (See 6.0, Trouble Shooting)
Amplier Input
When DC is located at the input stage only the DCA of the affected channel
is muted. (The other channel continues to operate normally). If the DC
signal at the input vanishes the microprocessor will de-mute the affected
channel and the amplier will work as usual again.
4.0 OPERATION