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2010 FiveFish Studios
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www.fivefishstudios.com
X-12 Microphone Preamp Kit
AUDIO TESTING
Connect a dynamic microphone to the input XLRs, connect a monitor speaker to the output XLR, turn power ON, set the gain
switch, adjust volume and you should hear sound come out of your preamp.
If using a condenser mic, turn phantom power switch to ON position. Check to see if the LED lights up. Wait a few seconds, and
your condenser microphone should start working.
Check that your LED VU meters are working and blinking.
NULL OFFSET VOLTAGE ADJUSTMENT
Now that we’ve verified our preamp to be working, let’s do some fine-tuning adjustment. Connect the black lead of your
multimeter to GND, and the red lead to the OUT pad on the PCB (nearest IC1).
Make sure your multimeter is set for DC voltage.
Adjust the trimmer shown above until you get a reading of close to 0volts on the OUT pad. A reading of 10mV or less should be
good. It is possible to get an adjustment reading of 1mV or less. (Just be patient trimming the pot.)
A good trim adjustment will reduce (if not completely remove) clicks and pops when changing gain settings.
