PRESONUS BLUETUBE User Manual page 9

is available to each channel input of the Blue
Phantom Power
Tube. The 48 volts is supplied by way of the XLR connector for
condenser mics and any other devices requiring continuous power
through the XLR input. This power is supplied at a constant level
allowing use of both inputs simultaneously.
XLR connector wiring for Phantom Power
Phase Reverse Switch
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.
-20 dB 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 MP20 and thus preventing the input signal from
over-modulating (distorting) the input. This may occur due to high
output level from a microphone or line device. Padding the input
serves to provide increased "headroom" for the operator.
Drive.
The Blue Tube Drive control increases the amount of signal
routed through the 12AX7 vacuum 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
PIN 1 GND
PIN 2 +48v
PIN 3 +48v
allows the user to invert the polarity of the