5
Switching on and off
In your sound reinforcement system, always switch on the amplifier after all the other equipment and always
switch it off before anything else, if possible with the gain controls set at minimum: this will avoid annoying
and sometimes dangerous signal peaks.
Installation and use
Your amplifier can dissipate a lot of heat, be sure to install it in locations with ensure correct air circulations.
Avoid long exposure to direct sunlight,sources of strong heat, powerful vibrations, very dusty or Particularly
damp surroundings or (even worse) rain: this will avoid possible faulty operation, deterioration or even electric
shocks and fires. The air for cooling the unit is forced in though the vents in the front panel and out though
those on the rear panel, so make certain that there sufficient space round the amplifier to allow adequate air
circulation.
If racks or flight-cases are used, make sure that airflow is unobstructed: don not install the amplifiers in racks
or flight-cases with closed backs. Since part of the heat is dissipated via the metal bottom of the amplifier, it is
advisable to install the amplifiers with at least one rack unit space between them.
Audio connections
Remember to always connect and disconnect other units with the amplifier switched off.
Always use good quality cables of the appropriate type.
Take care of your connector cables, a very frequent cause of audio problems. Check their condition
frequently. Always grip them by the connector, avoid pulling them forcefully and wind them without forming
knots or sharp bends, they will last longer this way and be more reliable.
Preventing or identifying interference
First of all, check that the amplifier is installed in a place free from industrial of RF (radio frequency)
Interference.
Avoid installing your equipment very near radio or TV sets, mobile phones, etc., as these can cause noisy
interference.
When connecting the other components of your sound system, watch out for the so-called ground loops,
which could cause hum and jeopardize the amplifier excellent signal-to-noise and low distortion
characteristics.
The best way (even if not always feasible) to avoid ground loops is to connect the electric ground of all the
equipment to a single central point (the so-called star system). In this case, the central point in sound systems
is the mixer.
To help identify the cause of any interference, connect the various sections of the mixer to the rest of the
equipment in the following order, listening to the resulting sound as you proceed with connection:
Outputs: ampl loudspeaker enclosures (master outputs);
Ampl monitors (AUX outputs);
Effects (AUX outputs or EFF send/return);
Inputs: instruments with line signals (keyboards, samples, recorders, etc.);
Microphones ( lastly and one by one).
