Input Selection; Mic Switch; Microphone Input - API 3124mb+ Operator's Manual

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4.3 Input Selection
Each preamplifier can receive three (3) input sources:
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4.3.1
4.3.2
HI‐Z IN: ¼" high‐impedance instrument input
LEVEL: Stereo mixer send level
PAN: Stereo mixer send pan
AUX: Auxiliary bus send level
VU METER: 7 LED VU meter
MIC (Microphone): Rear panel female XLR microphone input with switchable 48V phantom
power
INST (Instrument): Front panel ¼" unbalanced ‐10dBu instrument level input
MIC Switch
The MIC switch is used to select the input source. When the green LED above the switch
is illuminated, the rear panel XLR input is the active source. When the green LED above
the switch is not illuminated, the front panel ¼" input is the active source.
Microphone Input
Select the microphone input by pressing the MIC switch and a green LED should turn on
above the MIC switch. The MIC input connection on the rear panel will be the active
input.
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Female XLR microphone input
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48V phantom power
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‐20 dB pad
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Green LED illuminates when MIC switch engaged
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VU meter indicates level of preamplifier output
48V: Provides 48 volt phantom power to the MIC input female XLR connector
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Red LED above switch illuminates when engaged
IMPORTANT: Caution should be exercised when engaging phantom power! Damage
‐20 dB PAD: Inserts a ‐20 dB attenuator after the microphone input
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Yellow LED above switch illuminates when engaged
GAIN: microphone preamplifier level control
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10 dB minimum gain (including PAD)
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65 dB maximum gain (including PAD)
can occur if phantom power is applied to some audio devices, including
most ribbon microphones. The 3124mb+ output should also be fully
lowered when engaging the 48V switch.
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