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4. OPERATION AND USAGE
4.1. Start up
Pushing the POWER (7) button lights up the integrated pilot light and both red PROTECT (2) LEDs during
the approximately 10 seconds needed to stabilize all voltages. The PROTECT LEDs will then turn off meaning that
the amplifier is now operative.
In a complete audio installation, it is important to start up the equipment in the following sequence: sound
sources, mixer, equalizers, active filters and finally power amplifiers. To turn them off the sequence should follow an
inverse pattern.
4.2. Input attenuators
This consists of rotative potentiometers, situated on the front panel (1).
These attenuators enable the connection of different types of mixing consoles, independent regulation level
and loudspeaker connections that allow an inferior power level that the level already supplied by the power amplifier
at its maximum power, with no danger of damaging, by careless handling, the volume of the pre-amplified mixer.
Inside the device's packaging you will find a little plastic bag containing 2 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 DPA amplifiers are equipped with a simple but efficient indicators system.
Indicator PROTECT (2)
They point to the lack of signal at the speaker outputs. These indicators may light up due to following
reasons:
1. From the moment the machine is switched on, until stand by period finalise that is necessary for the
stability of the internal tensions of the power amplifier.
2. Because the amplifier output has short circuited.
3. If the amplifier is giving a continuous voltage or is of very low frequency, this could damage the
loudspeakers.
In any case, should these indicators permanently light up, it is a sign of malfunctioning and its cause should
be investigated.
CLIP indicators (4)
These illuminate when the signal given to the loudspeakers is 1,5dB before the real clip. This CLIP system
takes into account the possible variations in the mains voltage always giving a real indication even if the electric
mains varies. It is normal that working at high power levels, the CLIP indicators illuminate at the rhythm of the low
frequencies which are the ones that passes major energetic contents. Make sure these indicators are not
permanently illuminated.
THERMAL protection indicator (3)
Alerts of the tunnel cooling temperature when it has risen above 90 centigrade degrees. The amplifier will
then start up automatically when the temperature descends to 75 centigrade degrees.
The DPA power amplifiers feature separate thermal protection systems per channel. They operate
independently, meaning that if one channel triggers its protection system, the other one can perfectly continue its
normal operation.
SIGNAL Presence indicator (5)
It points to the existence of signal at the amplifier input. These indicators light up when the input signal
surpasses -40dB.
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.