Presonus Audio electronic TubePre user manual XLR wiring for phantom power, Phase Reverse Switch

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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