PRESONUS TUBEPRE User Manual page 9

XLR wiring for phantom power
PIN 1 GND
PIN 2 +48v
PIN 3 +48v
Phase Reverse Switch
Allows the user to invert the polarity of the XLR connector by switching
pins two and three. The inversion of the pins of the XLR connector may
be necessary to alter the audio phase of two like microphones to
compensate for phase cancellation. It may be required that the wiring
of a cable's XLR connector be switched to successfully utilize phantom
power.
-20dB Pad
Provides -20 decibels of attenuation with the push of a button. This is
a very useful feature for rapidly reducing the level coming into the
TUBEPRE and thus preventing the input signal from distorting the
input. This may occur due to a high output level from a microphone or
line device. Padding the input provides increased "headroom" for the
operator.
Drive
The TubePRE drive control increases the amount of signal routed
through the 12AX7 vacuum tube. (The gain controls overall volume,
whereas the drive controls volume routed through the tube.) The
effect achieved by this procedure can be subtle to extreme, depending
on the setting being used. A "warming up" of the sound can be noticed
at lower settings. This desirable effect is especially good for
microphones and on an electric bass and the resulting sound is
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