M-AUDIO Duo USB - Manual (Page 12)

jacks. Check your source or target device’s documentation for more information
on its operating line level.
Using the Mic Inputs
The Duo gives you two completely independent channels of high gain, ultra low
noise pre-amps. Each channel provides low impedance microphone inputs on
XLR connectors with optional phantom power. Dynamic, condenser, or any type
of low impedance microphone will interface easily with the Duo’s Mic Inputs.
You may also attach a direct box or passive transformer to the Duo’s Mic Inputs,
which will then allow you to plug an electric or acoustic guitar or other high
impedance instrument into the Duo’s Mic Inputs. This is also described in the
previous section, “Hooking Up Your Duo.” Additional information on using the
Mic Inputs will be found in the next three sections.
Setting the Gain
The Duo provides up to 60dB of gain on the XLR “Mic” inputs. Microphones
typically emit a low signal level, requiring a "pre-amp" such as the Duo provides.
Other instruments, such as guitar pickups and keyboard sound modules, may also
benefit from a little bit of punch from the Duo, when used in conjunction with a
direct box or passive impedance transformer.
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
signal LED shows fairly consistent activity, you’ve reached a good signal level
for the Duo mic preamp. 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 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 Duo signal.
You must also consider the level that is being sent from the Duo to your
recording software. Check the input meters within your software and make sure
that they are neither too low nor clipping (too ‘hot’). An adjustment in gain on
the Duo may be necessary, but your optimal recording level within your software
should be approaching but never reaching the maximum level.
You will find more information on setting record levels in the manual of your
music software. Understand that in digital recording, clipping is never a good
thing. If your level goes into the red once, you’ve got distortion!
12