mode output.
4.3
Ground Lift Switch
If hum is audible after switching on the ES 20, the cause may be incorrect earthing of your sound
system. The <GROUND LIFT> switch can be used to “lift” the connection between the system
earth and the mains earth. This action alone is often sufficient to eliminate the undesired noise
caused by a “bad grounding system”, or “ground loops”.
4.4
Indicators
Each channel of the amplifier is equipped with the following indicators:
•
Power: these LEDs will light when the amplifier is switched on.
•
Signal present: these LEDs will light when an input level of more than 40 dB under the
level that would cause maximum power (+6 dBu) is detected. The signal present LEDs
work independently of the settings of the input attenuators.
•
Thermal: when the output devices of a channel have reached a temperature of 90 °C,
the input of that channel is muted and the thermal LED will light. Both channels work
independently, so thermal overload of one channel does not affect the other channel.
In case of a continued overload of both channels, it is possible that the power supply
runs hot. In that case, both inputs are muted simultaneously.
•
DC: the DC LEDs indicate that the output of the amplifier is decoupled from the output
connectors. This occurs when the amplifier is switched on and the electronic circuits
need time to stabilise. This takes approximately one second. Besides, during normal
operation, the amplifier output is decoupled from the output connectors if a dangerous
DC voltage is present at the amplifier output.
When the DC LEDs light during normal use, check the following things: Disconnect the
speaker system. When the LED(s) switch(es) off, the DDC is probably not properly
connected.
When this does not solve the problem, the amplifier is damaged and should be re-
paired by an authorised Stage Accompany service centre.
•
Clip: this LED will light when the output level of the amplifier has reached its limit. The
indication is correct for every connected impedance. When the clip LEDs flash fre-
quently, distortion is to be expected.
OPERATION
stage accompany
R
ES 20 USER MANUAL
4-2
