M-Audio MobilePre USB User Manual page 24

Check the documentation that came with your microphone to see if you
need to switch on phantom power. As a rule, most FET condenser
microphones, such as the Groove Tubes GT57™, require phantom power.
Most tube condenser microphones, such as the Groove Tubes GT67™,
have their own power supply and don't need phantom power. Dynamic
microphones, like the Shure SM57™, don't need phantom power, and some
ribbon microphones can be damaged if you send phantom power. So if
you're unsure, check the microphone's manual or contact the manufacturer
or your M-Audio dealer.
Instrument/Line Inputs
Channels 1 and 2 have an Instrument/Line input as well as the microphone
input. If you want, you can plug one signal into the Channel 1 Mic input and
another signal into the Channel 1 Line input. However, these signals will be
mixed and both recorded on Channel 1, and you won't have any control
over the balance between the two signals. A better solution in this case
would be to use the Channel 1 Mic input and the Channel 2 Line input.
The Instrument/Line input accepts an instrument level signal, such as an
electric guitar or bass, or a line level signal, like a synthesizer or drum
machine. The Channel 1 and Channel 2 Gain controls on the front panel
control the level of the Instrument/Line inputs. Adjust the gain control
while watching the meter in your digital recording software. If your
recording software doesn't have an input meter, you can check the tiny
meter on the MobilePre USB's front panel.
MobilePre USB Outputs
The rear panel of your MobilePre USB has two sets of outputs: a pair of
1/4" jacks (labeled Output 1 & 2) and a single 1/8" stereo jack (labeled
Stereo Line Output). Either of these outputs can connect to a set of
powered speakers for monitoring.You can also connect the outputs of the
MobilePre USB to a mixer or a stereo receiver.
Use whichever set of outputs fits the inputs of your monitor system, but
you should only connect one or the other. If your speakers or receiver
uses RCA jacks instead, you can purchase a converter, like the one pictured
here, at an electronics store such as Radio Shack.
White = Left
Red = Right
1/8" Stereo Mini Jack
(2) Female RCA Jacks
Note that the outputs of the MobilePre USB are Line Level. You can
connect these outputs directly to the inputs of powered speakers.
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