4 OPERATION

P.18

4.2.2 Signal LEDs

The green Signal LED is illuminated when the voltage level at the output reaches approx. 4 V; this corresponds to a power of approx. 4 W over a 4 Ohm resistor.

4.2.3 Clip LEDs (multifunctional)

The colour of the bi-coloured (green/red) LED changes between red, green and yellow depending on the load and the signal modulation conditions. (Yellow is created by a mixture of red and green light).

The intensity of the green light is defined by the current passing through the output stage of each channel (lowest brightness is proportional to approximately 1 A, the maximum brightness reflects the maximum output current). The red colour indicates the amount of signal clipping in each respective channel. If the green LED (current indicator) and red LED (clipping indicator) light up simultaneously, the Clip LED is yellow.

USER MANUAL

VORTEX 6, 4, 2.6 and 200V

If the amplifier is overdriven for prolonged periods, the Clip LED will appear red to alert the user more effectively (the green component of the LED is switched off).

Monitoring the output current and clip via the LEDs can aid the detection of incorrectly wired components and faults in the loudspeakers at an early stage. (See 6 Troubleshooting)

4.3Power Amp Protection Systems 4.3.1 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 DCA. The strategy is implemented in software. For sinusoidal input signals the microprocessor limits the input signal in such a way that non-linear distortions of the signal never exceed 1 %.

The Clip Limiter can work on each channel independently (except in the two mono-operation modes).To disable the Clip Limiter, see 4.1.4 Limiter Switch.

4.3.2Under Impedance Limiter

As a result of incorrectly connected or defective loads,under impedance or even short circuits may occur in one or both power amp channels.

The microprocessor constantly calculates the load impedance at the output channels. If an impedance of less than 1,33 ohms/channel (2,7 ohms/channel for VORTEX 200V) 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 On LED is turned off. (See 6 Troubleshooting)

4.3.3 SOA Protection

To ensure that the power transistors are only used in the Safe Operation Area (SOA), the SOA-protection in stereo mode switches back the rail voltages of the respective power stage. In mono modes the rail voltages of both channels are switched back.