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CONTRACTOR PRECISION SERIES
12 Owner‘s Manual
3 Operation
3.1 Volume Control
In DUAL and PARALLEL mode, the level controls LEVEL on the power amp’s rear panel are used to control
the amplification of the corresponding channel. Turning the control to the right increases and turning it to the
left decreases the volume. In BRIDGED mode operation, the output volume of the power amp is only
controlled by the CH 1 level control. Any changes in the setting of the CH 2 level control are ignored.
3.2 Indications
PROTECT
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. In that case, the output
relays separate the power amps from the load connected to prevent the connected loudspeaker systems
and the power amplifiers as well 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.
MUTE
The MUTE LED lights red whenever the power amp’s output signal is being muted, which happens when
manually muting the output signal via IRIS-Net™.
-30dB...LIMIT
Level indication is realized via vertical LED chains on the power amp’s front panel that individually indicate
the actual levels of each channel at -30dB, -10dB and -3dB below full modulation. The LIMIT LED lights as
soon as the integrated dynamic audio limiter is 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
controls input levels of up to +21 dBu down to a THD of approximately 1 %. If, on the other hand, the LIMIT
LED light constantly, reducing the volume is recommended to prevent the loudspeaker systems connected
from being damaged by probable overload.
POWER
The POWER LED lights green when the power amplifier is on. If the POWER-LED does not light, despite
the fact that the amplifier has been switched on, this indicates that the power amp is not connected to the
mains or the primary fuse has blown.
STANDBY
The STANDBY-LED lights yellow when the power amp is in standby mode. Standby mode reduces the
amp’s power consumption to an absolute minimum. Activating the standby mode is possible via IRISNet™
or the POWER REMOTE port at the amp‘s rear panel.
IRIS-Net
The IRIS-Net-LED lights blue if an IRIS-Net™-compatible remote control module has been installed in the
power amp’s extension slot and successful data communication has been established. The IRIS-Net LED
blink slowly whenever the “Find” function in IRIS-Net™ is being used to locate a power amplifier in the rack.