W W W . P S S O . D E
25
7
OPERATION
Switching On/Off
1
To prevent loud switching noise, always switch on all other units of the amplifier system before
switching on the power amplifier. After operation, switch off the power amplifier first. Prior to switching
on set all level controls to the left stop position and make sure that the operating mode selector switch
MODE is set to the correct position.
2
Switch on the amplifier with the power switch. The protection indicators PROT light up for about 10
seconds. If they do not, check if the amplifier is connected to the mains correctly. After the turn-on delay
the speakers are activated (protection indicators PROT are off). Afterwards the power indicator ON
lights up and indicates that the amplifier is switched on.
Input Level Adjustment
With the DIP switches
SENSITIVITY
the input sensitivity of the amplifier can be matched to
the output level of the preceding unit.
Adjusting the Level
1
First, set the volume controls of the preamplifiers to zero and turn the level controls of the amplifier to
mid-position. There should be no loud humming. Should humming persist, check the connection cables
between the preamplifier and the amplifier (switch off components before).
2
Adjust the level controls to the desired volume value. The LEDs
“-10 dB
” and
“-40 dB
” show the
adjusted input level. In case of overload, the red
CLIP
indicator lights up. In this case, reduce the
volume correspondingly.
3
In bridge mode the level controls for channel 2 and channel 4 are disabled. Volume adjustment is made
with the level control for channel 1 and channel 4.
Additional information on the operation
When operating the amplifying system, please make sure that the loudspeakers always sound well. When
distortions can be heard, either the amplifier or the loudspeaker is overloaded. Overloads can quickly lead to
amplifier or speaker damage. In order to avoid damage, please reduce the volume immediately when distortions
can be heard. When speaker systems are destroyed by overload, the guarantee becomes void. Always check the
sound pressure level with a meter in order to keep to the threshold.
Protective Circuits
The integrated protective circuits prevent damage to the speakers and the amplifier. If activated, the
speakers are electrically separated from the amplifier and the protect indicator
PROT
lights up:
•
for approx. 10 seconds after switching-on until the speaker outputs are ready for operation
•
in case of overheating of the amplifier
•
in case of a VHF signal above 10 kHz at a speaker output
•
in case of a short-circuit at a speaker output
•
in case of a DC voltage at a speaker output
If the red protect indicator
PROT
lights up during operation or if it does not extinguish after switching on, the
amplifier has to be switched off and the cause of the fault has to be removed.
