M-Audio MobilePre USB [23/29] Microphone inputs

Optimize for Slower Systems: Only the Mac OS 9 version of the

Mobile Pre control panel has this checkbox. It should be left checked if

your computer’s processor is of G3 or slower speed.

Using the MobilePre USB

Now that we’ve finished connecting speakers and setting levels, you’re

probably interested in getting started. This chapter explains how to

connect microphones and speakers to the MobilePre USB, and will explain

some of the units typical applications.

MobilePre USB Inputs

There are 6 inputs on the MobilePre USB, which are broken up into

functional pairs for XLR, 1/4” Line Level and a Stereo 1/8”. All of these

inputs are merged into the same corresponding input channels on the

MobilePre USB.Any or all of these inputs can be used at any time, however

only 2 channels of audio will be recognized by your audio application.Your

software will record anything that is plugged into any of the MobilePre

USB’s inputs.

Microphone Inputs

The MobilePre USB has two microphone inputs, labeled Ch. 1 and Ch. 2.

These XLR inputs raise the gain of a microphone level signal to a line level

signal for recording. If your microphone does not have an XLR output, you

will need to purchase an adapter or impedance transformer or use the

Stereo Mic Input, explained below. You can control the level of the two

microphone inputs using the Channel 1 and Channel 2 gain controls on the

MobilePre USB’s front panel.

The 1/8” stereo input connects to the same channels as the 2 XLR

microphone inputs. It is provided for use with stereo dynamic

microphones or self-powered stereo condenser microphones with 1/8”

stereo outputs. Do not confuse this jack with similar looking jacks found

on consumer sound cards, which accept only mono microphone signals

that require a bias voltage to the microphone.

Phantom Power

The MobilePre USB provides phantom power for condenser microphones.

This 48 volt phantom po

wer source can be switched on or off using the

front panel switch. An LED indicator lights when phantom power is

switched on and sending po

er to both micr

ophone inputs.