Operation; Operating Mode; Switching On/Off; Indicators - Omnitronic MCR-4250 Bedienungsanleitung

8. OPERATION

8.1 Operating mode

Select the operating mode (stereo or bridge) for the corresponding channel.
All channels feature a high pass filter to attenuate low frequencies. The amplifier should preferably be used
with active filters. To activate a filter, set the corresponding ON/OFF switch to the "ON" position

8.2 Switching on/off

After having connected your amplifier to the mains, turn both gain controls counter-clockwise to Min-position.
The last device to be switched on is the amplifier. The PROTECT LED lights up for approx. 3 seconds after
switching on. If it does not, check if the amplifier is connected to the mains correctly. After the turn-on delay
the speakers are activated (PROTECT-LED is off). The power indicator, the SIG LED and possibly the
BRIDGE LEDs light up afterwards.
If you want to switch off the system, switch off the amplifier first and then the pre-amplifiers in order to avoid
acoustic shocks on the speakers.

8.3 Indicators

All important operating modes of the amplifier are arranged on the front panel.
SIGNAL
CLIP
PROTECT
BRIDGE
POWER ON
REMOTE ON

8.4 Adjusting the level

After having set the volume controls of the pre-amplifier in null-position, turn the gain controls of your
amplifier to mid-position. You must not hear any loud humming. If there is humming nevertheless, check the
connecting cables between the pre-amplifier and the amplifier (switch off components before). Now adjust
the volume with the gain controls.
Caution! Increase the level of each channel only so far that the CLIP-LED lights up shortly. Thus, you avoid
that the output signal is distorted and your speakers are damaged.
In bridge operation of channel CH1 and CH2 turn the level control CH2 to zero and adjust the volume with
the control of CH1 only. In bridge operation of channel CH3 and CH4 turn the level control CH4 to zero and
adjust the volume with the control of CH3 only.
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.

8.5 Protective circuits

The protective circuits prevent damage to the speakers and the amplifier. If activated, the speakers are
electrically separated from the amplifier and the PROTECT LED lights up:
1. for approx. 3 seconds during the stabilization period after switching on
2. in case of a short-circuit at a speaker output
3. in case of overheating of one of the channels
4. in case of a DC voltage at a speaker output
5. in case of a VHF signal at a speaker output
input signal
short-circuit or incorrect impedance or signal distorted
active during stabilisation period after switching on or when one of the
protective circuits started
bridge operation selected
power indicator
remote active
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