Phantom Power; Loudspeaker Output; Loudspeaker Loading - ADS 3120 Plus Operation Manual

All inputs are configured as AUX inputs. To configure them as balanced microphone inputs
proceed as follows

disconnect the power supply then remove the amplifier top cover

locate the correct switch on the rear PCB
(MIC 4 is the centre one and MIC 5 the right hand one when viewed from
the front of the amplifier)

set the switch to the position nearest to the front panel

replace the amplifier top cover.

Phantom Power

Each of inputs has the option of phantom power, providing 18Vdc phantom power on the
XLR socket. This is often used to power external low current devices such as electret
condenser microphones. Phantom power is selected by jumpers located internally on the
input board of the amplifier.
NEVER remove the top cover of the amplifier or make an internal
adjustment with the ac mains supply connected. All internal
adjustment must be performed by a competent, qualified engineer.
Having taken all the necessary electrical safety precautions, remove the top cover of the
amplifier and locate the phantom power jumpers for the five microphone inputs. Select the
appropriate jumper setting (by moving the jumper if necessary) for phantom power to be
off or on, as indicated on the inset diagram below.

Loudspeaker Output

Two loudspeaker outputs are available – Music & Speech and Speech Only.

Music & Speech gives an output at all times.

Speech Only gives an output during a priority condition.

Loudspeaker Loading

To allow sufficient transient overload margin it is suggested that the output load should not
exceed approximately 70% of the rated power output.
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