Operation And Usage; Start Up; Input Attenuation; Indicators - Ecler MPA4-150 Bedienungsanleitung

Remember that the minimum load impedance for stereo or mono amplifiers is 4Ω. In
bridged mode the impedance must be not less than 8Ω. For a reliable operation under any
circumstance connect lower load impedances than just specified.
Attention: In bridged mode, use only the red terminals.

4. OPERATION AND USAGE

4.1. Start up

To switch the unit on just push the switch labelled POWER (14) and the integrated
pilot-light will light up. We highly recommend the "safe power-up sequence": First the sound
sources, then mixer, equalizers and active filters and, finally, power amplifiers. Powering off
should be done by following the exact reverse sequence in order to avoid any possible peaks
reaching the next device, and consequently protecting the loudspeakers, which are specially
sensitive to these peaks.

4.2. Input attenuation

These are rotary trimmers located on the front panel (1, 4, 7, 10).
control and the connection of speakers not able to handle the amplifiers maximum output power,
thus avoiding the risk of damaging them with the mixers or preamps volume control.
Inside the device's packaging you will find a little plastic bag containing 4 transparent
caps which protect the input attenuation settings from unwanted manipulation. These caps are
transparent in order to let you visualize the current settings.
Once inserted, they cannot be removed with bare fingers, for this purpose, a small
screwdriver is needed.

4.3. Indicators

The SP signal presence indicators (2, 5, 8, 11) light up when the input signal reaches
approximately -40dBV.
The CLIP indicators (3, 6, 9, 12) light up when the output signal for the speakers is
-1.5dB below the actual clipping threshold. This clipping system watches for eventual supply
voltage variations, thus giving always an accurate clipping indication, regardless of mains
voltage deviations.
It is normal that when operating at high output power, the CLIP indicators light up in
synchronisation with the low frequencies, which carry the most energy. Nevertheless, you
should avoid that the CLIP indicators are lit continuously.

5. CLEANING

The front panel should not be cleaned with dissolvent or abrasive substances because
silk-printing could be damaged. To clean it, use a soft cloth slightly wet with water and neutral
liquid soap; dry it with a clean cloth. Be careful that water never gets into the amplifier through
the holes of the front panel.
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These attenuators allow the connection of different mixers, an independent volume
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