4 OPERATION

P. 16

4.2 Controls

4.2.1 Volume Control

A volume control with 41 notched settings controls the audio signal. These settings have been selected to correspond to human hearing characteristics (logarithmically) and therefore guarantee an optimal range of settings for practical applications. Each channel can be set individually.

Set the volume to zero before turning on the amplifier to prevent the occurrence of sudden high volume levels which may cause damage to your hearing and/or the speakers.

4.2.2 Gain Selector

A switch on the rear of the Q-POWERamplifiers allows the maximum amplification attainable to be set directly in the input stage.

The Q-POWERamplifiers have a 26 dB and 32 dB voltage gain setting along with a 1,4 V sensitivity setting.

4.2.3 Limiter Switch

This switch is located at the rear of Q-POWERamplifiers. It allows you to activate the clip limiter function on the channels A/B and C/D respectively.

4.3Power Amp Protection Systems 4.3.1 Clip Limiter

If the power amp is overdriven and the limiter is set to on (see section 4.2.3) the clip detection triggers the Attack-Release-Circuit (ARC). The ARC delivers the control voltage for the gain reduction.

USER MANUAL

Q - P O W E R S E R I E S

Q - P O W E R

S E R I E S

4.3.2 SOA Protection

Whenever the power transistors leave their Safe Operation Area (SOA),the SOA- protection will either switch back the current rail of the respective channel (Q-POWER 6) or limit the maximum load current in the power transistors (Q-POWER 10).

4.3.3 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 corresponding channel will be muted.If DC was only applied for a short moment,the amplifier will release mute and work as normal. If DC is applied for longer periods or several short times the amplifier will switch to standby mode.

If this happens, switch off the amplifier, wait until all indicator LEDs extinguish and switch the amplifier on again.

4.3.4 DC Servo

To prevent DC Offset at the speaker output the Q-POWERamplifiers are fitted with a DC Servo.

4.3.5 Over Current Protection

Over current is permanently controlled in the output stage. In case of exessive loading the maximum output current of the amplifiers is automatically limited. This improves reliability without degrading sound quality when driving complex loads.

4.3.6 Thermal Protection

There are sensors in each amplifier heatsink in order to ascertain temperature data. If a temperature of more than 85 °C is detected at the heat sinks, the input signal on that channel is reduced proportionally to prevent further heating of the amplifier. If the temperature exceeds approximately 100 °C, the main SMPS is switched off(safety shut-off).