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13
Setting Up and Using the MPL 1640
f. If any condenser microphones are connected to the MPL 1640, turn on the
Phantom switch.* Then turn on the MPL 1640—the Power LED in the
meter section will light up. Finally, turn on the power amplifier.
g. Play an instrument connected to one of the MPL 1640’s line inputs** and,
while doing so, raise the corresponding channel fader to the “0” position.
You should see the segment meter begin to move—adjust the input trim
control for that channel so that the “0” segment lights frequently and the
“+3” segment lights only occasionally. If the incoming signal seems too hot
even with the input channel trim all the way at its minimum (+4) setting, you
may need to lower the output level of the instrument, though this will rarely
occur. Conversely, if the signal is too low even with the input channel trim
all the way up, something's definitely wrong: in all likelihood, the connecting
audio cable is faulty.
h. Once you’ve set the optimum level in step (g) above, continue playing the
instrument and slowly raise the power amplifier volume until you get the
level you want to hear.
i. Repeat step (g) above for each instrument connected to the MPL 1640
channel line inputs.
j. The procedure for setting optimum microphone levels is virtually identical;
sing or speak into the mic at the level you expect to use in performance
while slowly raising the fader for that channel to its “0” position. Then adjust
the input trim control for that channel while watching the meter. You should
expect that microphone inputs will require rather more in the way of input
trim boost than line inputs.
k. If you have any outboard signal processors connected to the Aux send and
return jacks on the rear panel, follow this step. Because outboard effects
processors can sometimes be quite noisy, it’s particularly important to maxi-
mize the amount of signal being sent to them via the MPL 1640 Aux sends.
The idea is to drive these devices as hot as possible (short of overloading
them) and to then use the corresponding Aux return level to carefully adjust
the amount of processed signal being blended with the dry signal. To set
optimum Aux send levels, use a channel that has already had its gain struc-
ture adjusted in step (g) or (j) above. Turn all three Aux send knobs for that
channel to their “0” (unity gain) position and then play the instrument (or
sing into the microphone) connected to that channel. Adjust the input levels
of connected outboard effects processors so that their meter shows incom-
ing signal normally in the 0 VU range (with just occasional higher excur-
sions). Then it’s time to optimize the Aux return levels. While continuing to
play your instrument (or continuing to sing into the microphone), slowly raise
each Aux return level control until you hear the desired amount of
processed signal added to the dry signal. For more information, see the
“Using the Auxiliary Sends and Returns” section on page 20 of this manual.
* CAUTION: Before turning phantom power on, be sure to disconnect all non-
microphone signal sources (such as direct injection boxes) from the XLR
mic jacks (channels 1 - 10).
** If you're using an instrument such as electric guitar or bass, we recommend
that you connect it to the MPL 1640 with a direct injection box to ensure cor-
rect impedance.