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1) Power up the UnFairchild and let it warm up for 5-10 minutes.
2) Set the BYPASS/VU switch to GR.
3) Set the channel mode switches to IND.
4) Set the INPUT GAIN controls to your UNITY GAIN setting
(typically 12).
5) Turn the THRESHOLD”controls to 10
(fully clock-wise).
6) Send a +4dB 1Khz sine wave test tone to both channels.
7) You should see anywhere from -7dB to -12dB of gain reduction on the meters. If channel A and
channel B are not compressing the same amount, you can match them by adjusting the trim pots.
(See figure 3).
VU METER OUTPUT LEVEL CALIBRATION
The VU meters are calibrated at the factory with Audio Precision test equipment to make sure 0dB
on the meter is e4dB when metering output level. If these drift, or if you would like to
have a different calbration for the meters, manual calibration can be accessed through small holes
on the right side of the chassis:
1) Power up the UnFairchild and let it warm up for 5-10
minutes.
2) Set the BYPASS/VU switch to VU.
3) Set the INPUT GAIN controls to your unity gain setting
(typically 12).
4) Send a +4dB 1Khz sine wave test tone to both channels.
5) Connect the outputs of the UnFairchild to an external
meter you trust.
6) Adjust the GAIN TRIM until the external meter reads
e4dB.
7) Adjust the VU meter trim pots until the meter is exactly
at the 0dB marking.
Channel A
Channel B
