Setting The Tube Plate Voltage - Art MPA Gold User Manual

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ART MPA Gold™ Microphone Preamplifier
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 resonance. Higher impedance settings provide a more "open" sound. Lower
impedances tend to focus the sound more.

Setting the Tube Plate Voltage

The MPA Gold allows the user to select between one of two vastly different tube bias
settings 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 "Warm" setting produces a smooth transition from very clean low levels up to a
"round" saturated clipping on peaks. This setting is reminiscent of old tube gear, and is
intended 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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