Phantom Switch; Phase Switch; Plate Voltage Switch - Art DIGITAL MPA II User Manual

Phantom switch

Phantom power on the microphone input is turned on and off with this switch. Depressing the switch
will power condenser microphones and other 48volt phantom powered devices. Phantom power is
supplied to pins 2 and 3 of the input jack.
NOTE:
1) Dynamic microphones are NOT affected by Phantom power, although it should be turned off when
using dynamic microphones or line level inputs.
2) Although the 48volt phantom power ramps up and down slowly it may still create a pop. Mute the
output of the DIGITAL MPA II when engaging or disengaging phantom power to prevent damage to
equipment following the DIGITAL MPA II.

Phase switch

The Phase switch can invert the phase of the audio signal path in either channel. The Phase switch
is located after the tube circuit in the signal path, so you can hear slight differences between different
phase selections in the "normal" plate voltage mode near saturation. There are a number of reasons
why adjusting the phase is needed these include, wiring errors and inversions in some audio equip-
ment. Some microphones sound different depending on the phase chosen.
If two microphones are out of phase, they may cancel at various frequencies (depending on the
distance between them). If this happens, try changing the phase of one of the microphones and see if
there is an improvement.

Plate Voltage switch

This switch sets both the tube bias point and the plate voltage level the balanced differential tube
circuit runs at. The amount of headroom is adjusted by using the Gain switch and the input Gain
control. The DIGITAL MPA II takes about 10-30 seconds to smoothly transition from one mode to the
other. There is a slight increase in gain in the "High" plate voltage mode.
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