M-AUDIO DMP3 - Manual (Page 6)

5 DMP3 | User Guide
Setting the Gain
The DMP3 provides up to 66dB of gain on the XLR and 1/4” high impedance inputs.
Microphones and guitar pickups typically emit a low signal level, requiring a "pre-amp"
such as the DMP3. Other instruments, such as keyboard sound modules, may also
benefit from a little bit of punch from the DMP3.
Plug in your mic or instrument with the gain controls turned down, then turn the gain up
incrementally while testing the mic or playing the instrument. When the VU meters
show activity at a fairly consistent level, you’ve reached a good signal level for the
DMP3 (see section, “VU meters”). Some users may wish to experiment a little further
to find what audibly might be referred to as a "sweet spot." Note that when the "clip"
LED lights, it is indicating that the signal is at least 4dB below clipping. Let your ears
be the judge, but when the clip LED lights and stays lit, you are approaching or have
reached distortion in your DMP3 signal.
NOTE: You must also consider the level that is being sent from the DMP3 to
your recording device, sound card input, mixer or sound system. Check the
input meters at the receiving device and make sure that they are neither too low
nor clipping (too ‘hot’). You may be able to adjust the input level or operating
line level of this device, otherwise an adjustment in gain on the DMP3 may be
necessary.
Sound cards and other recording devices may or may not have an input level
adjustment. If your recording device (tape recorder, computer & sound card, etc.) does
not provide input level adjustments, then the signal level that you use to record will rely
totally on your source (voice/mic, guitar/instrument, etc.), and the level you set on the
DMP3. If your recording device does provide input level adjustments, then we suggest
using a unity gain setting as a starting point. This is usually around the 2:00 position,
though your user guide may provide more information.
VU Meters
The VU meters on the DMP3 are there to provide a visual reference to the signal at the
output of the DMP3. They are, however, calibrated to correspond more closely to the
level you will see on a recording device that has digital peak meters to show input level.
VU meters show an average of the signal voltages, while peak meters show the true
peaks in that signal. Peak meters are, in that sense, more sensitive than VU meters, and
are more affected by timbre and pitch. It is possible that a peak meter could be
approching the 0dB level (the maximum possible before clipping), while the VU meter
shows very little movement.
The VU meters on the DMP3 are adjusted so that a more accurate visual representation
is created in relation to the peak meters in your computer or digital recording device. As
mentioned, this relationship will vary between instruments of different timbre and pitch.
Because of that, you may want to compare the DMP3 VU levels to the inputs levels on
your recording device for each performance, and decide how “hot” you can go on the VU
meters before clipping occurs on your recording device.