FRONT PANEL
Use the POWER switch located on the front panel to power-on the appliance. The soft-start function protects against current inrush peaks on the mains, which in addition prevents the mains line protection switch from activating during power-on. The loudspeaker outputs are activated via relay switching with a delay of approximately 3 seconds to efficiently attenuate eventual power-on noise. The PROTECT LED lights during the delay time and the fans run at maximum speed. This is normal, confirming the protection circuitry’s immaculate operation.
This indicator lights when the power amplifier has been switched on. Causes for the POWER-indicator not lighting are: the appliance is not connected to the mains network or a defective primary fuse
The PROTECT LED lights indicating that one of the internal protection circuits against thermal overload, short-circuit, Back-EMF, HF-occurrence at the output, etc., has been activated. The output relays interrupt the connected load from the power amps while input signals are interrupted as well, preventing the connected loudspeaker systems and the power amplifier itself from being damaged. Whatever caused the fault – e.g. a short-circuited speaker cable – needs to be remedied. In case of thermal overload you have to wait until the power amplifier automatically regains normal operation.
The SIGNAL LED lights as soon as an audio signal of approximately 30dB below full modulation is present at the output. The LED is dimmed when speaker cables are short-circuited or a protection circuit has been activated
The 0dB LED lights whenever the power amplifier is driven at its limits. Higher input voltage does not result in higher peak output voltage. In addition, the 0dB indicator comes in handy when adjusting external limiters.
This indicator lights as soon as one of the integrated dynamic audio signal limiters is being activated and the power amplifier is driven at the clipping limit or generally at its maximum capacity. Short-term blinking is not a problem, because the internal limiter trims input levels of up to +21dBu down to a S/N-ratio of approximately 1%. If, on the other hand, this LED lights constantly, reducing the volume is recommended to prevent the loudspeaker systems connected from being damaged by probable overload.
Detent potentiometers scaled in dB for adjusting amplification levels of SUB and TOP channels. To prevent distortion in mixing consoles connected to the amp, setting these controls to a value between 0dB and +6dB is generally recommended. The dB-scale provides direct indication of the control attenuation applied to the fixed internal amplification.
