Great River Electronics MP-2NV User Manual
Page 3
Definitive
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Design
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Front Panel Controls and Buttons
Gain Staging
The NV Series preamplifiers offer comprehensive gain staging capabilities, controlled by two
knobs on the front panel. The large gain knob adds an increment of 5db of gain with each step,
while the small output knob, the pot, delivers continuous adjustment of the output level. The
input range of the large knob is 0db to 60db and the output range of the small knob is
approximately -22db to +10db relative to the "CAL" marking on the front panel. The overall
maximum gain is 70db in the 1200 ohm input impedance mode.
Great River Tips:
Generally, the signal will be affected the least by keeping the large knob turned down and the
small one up. More coloration occurs when the input stage does most of the work, so cranking
the large knob and trimming back the output control will tend towards a thicker sound. When
the input stage clips, it gets ugly, so keep an eye on it.
Hi-Z (Direct Injection)
The Hi-Z or Direct Injection (DI) jack presents approximately 1.2 megohm impedance and utilizes
a unique FET/Bipolar buffer amplifier to drive the input transformer. This presents the proper
input load to an instrument, yet allows tonal shaping by changing the load on the input buffer
with the impedance switch.
Great River Tips:
Many instruments will benefit from the added coloration of this input. More coloration will
happen sooner with the impedance button in.
This is an “instrument” level input, not “line” level, so putting a full “+4dBu” signal into it is
likely to distort on peaks.
Phantom
When the phantom button is pushed in, a 48v supply to the microphone is activated. This supply
is compliant with the P48 standard, it supplies a full 48v, the resistors are matched 6.81K, and
will withstand a short circuit indefinitely.
Great River Tips:
Be sure you use the phantom supply only with microphones or DI boxes that require powering.
It is possible to damage some devices plugged into the preamp if long-term application of
phantom power is allowed.
Polarity
When the polarity button is pushed in, the polarity of the output XLR jacks is reversed. Note, this
does not invert the polarity of the –10dBv output.
Great River Tips:
The polarity is inverted by a relay that cross connects pins 2 and 3 of the output XLR. Try the
polarity button when doing vocals, many times the quality of the signal fed to the headphones
can be dramatically improved for the singer by getting the polarity “right”.