Setting The Tube Plate Voltage - Art PRO MPA II User Manual

We provide a continuously variable impedance control to allow you to fine-tune the voicing, finding
the perfect interaction between microphone and pre-amp.
Start by setting the centering the Input Impedance knob. This provides a 600-Ohm load.
Lower impedance loads will reject more noise picked up by cabling, and dampen microphone reso-
nance.
Higher impedance settings provide a more "open" sound. Lower impedances tend to focus the sound
more.

Setting the Tube Plate Voltage

The PRO MPA II allows the user select between one of two vastly different tube bias and power
supply levels. The transition between either setting is smooth and quiet and the gain variation is
minimal.
NOTE: It takes 15-30 seconds for the tube circuit to fully transition between either mode. During this
time, the unit passes a signal and the only noticeable change is a slight increase in level in the
"HIGH" setting.
The "Normal" setting produces a smooth transition from very clean low levels up to a "round" satu-
rated clipping on peaks. This setting is reminiscent of old tube gear, and used to get the most tube-
like sound out of the unit. Common uses include tracking with instruments.
The "High" setting of the plate voltage switch has increased bandwidth and headroom, very low
distortion and runs extremely clean until it reaches a point of saturated clipping. The clipping is well
controlled and still sounds natural. This setting is incredible on vocals.
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