Samson MPL 1502 User Manual

14
You’re now ready to establish the correct gain structure—the key to getting the
best performance from the MPL 1502, or from any mixer, for that matter. This is
a simple procedure that ensures optimum input and output levels so that no
unnecessary noise (caused by too low a signal) or overload distortion (caused by
too high a signal) is created. Here’s a step-by-step description of how to do so:
a. With all connections made (as described above) but with
the power amplifier
and MPL 1502 off, start by setting the power amplifier volume to minimum. On
the MPL 1502, turn all channel gain controls fully counterclockwise (to their “-∞”
position), and then set the Main gain control to its “0” position.
b. Set all channel input trim knobs to their fully counterclockwise (+4) position.
c. Set all channel equalizer and pan/balance knobs as well as both Aux return
balance knobs to their center detent “0” positions.
d. Set all channel Aux send knobs and both Aux return level knobs to their fully
counterclockwise (“-∞”) position.
e. Turn on all devices connected to channel line inputs and Aux returns and set
their level controls to unity gain or, if there is no unity gain indicated on their out-
put control, to maximum. If you’ve got outboard effects processors connected to
Aux returns, make sure they are sending completely “wet” (processed) signal,
with no “dry” (unprocessed) signal mixed in.
f. If any condenser microphones are connected to the MPL 1502, turn on the
rear-panel Phantom switch.* Then turn on the MPL’s rear-panel Power switch—
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 1502’s line inputs** and,
while doing so, slowly raise the corresponding channel gain control to the center
detented “0” position—you should see the MPL meter begin to move. Now
carefully adjust the input trim control for that channel so that the “0” segment in
the meter lights frequently and the “+2” 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 reach the level
you want to hear.
i. Repeat step (g) above for each instrument connected to the MPL 1502
channel line inputs.
* CAUTION: Before turning phantom power on, be sure to disconnect all non-
microphone signal sources (such as direct injection boxes) from the mic jacks.
** If you’re using an instrument such as electric guitar or bass, we recommend
that you connect it to the MPL 1502 with a direct injection box to ensure correct
impedance.
Setting the Correct Gain Structure

Samson MPL 1502 Specifications

Audio Specifications

frequency response	17 Hz to 30 kHz ± 1.5 dB at +4 dB
equivalent input noise channel 1-5 mic input	-128 dB (A filter, 150 Ω shorted)
equivalent input noise channel 1-15 line input	-131 dB (A filter, input shorted)
total harmonic distortion + noise	Less than 0.03 %
input level channel 1-5 mic input	-50 dBV to +4 dB (10 kΩ, balanced XLR)
input level channel 1-15 line input	-40 dBV to +14 dB (10 kΩ, balanced stereo phone jack)
input level aux return 1-2	+4 dB (47 kΩ, unbalanced phone jack)
maximum input level channel 1-5 mic input	+17 dB
maximum input level channel 1-15 line input	+27 dB
trim gain range	0 dB to +54 dB
channel fader range	+15 dB to -80 dB
aux send gain range	+10 dB to -75 dB
crosstalk ch-to-ch (1 kHz)	-80 dB
crosstalk stereo ch L/R (1 kHz)	-65 dB
standard output level main out	+4 dBV (balanced, 600 Ω loaded)
standard output level aux out	+4 dBV (unbalanced, 2.2 kΩ loaded)
standard output level headphones	150 mW (30 Ω loaded)
maximum output main out	+22 dBV (balanced, 600 Ω loaded)
maximum output aux out	+22 dBV (unbalanced, 2.2 kΩ loaded)
maximum output tape out	+22 dBV (unbalanced, 600 Ω loaded)
tone control high	10 kHz ± 15 dB
tone control mid	800 Hz ± 12 dB
tone control low	80 Hz ± 15 dB

Weight and Dimensions

dimensions	13.8 in (w) x 10.4 in (d) x 3.2 in (h)
dimensions metric	350 mm (w) x 264 mm (d) x 82 mm (h)
weight	7.7 lbs • 3.5 kg