Calibration
There are three trimmers on the PCB which need adjusting correctly to get the best out of the
ring modulator module. It is important that you adjust these in your modular as the settings
are affected by the power supply voltages.
Allow the modular and ring modulator to warm up for 15 minutes.
BAL1:
Turn down X LEVEL and Y LEVEL pots to their minimum settings. Turn the Y
OFFSET pot to its maximum level. Measure the output voltage from the output socket with a
good digital voltmeter. Adjust BAL1 until the output voltage is 0.000V +/- 5mV.
BAL2:
Insert a triangle wave signal at 440Hz to the IN Y AC input. Turn down the Y
OFFSET pot to its minimum setting. Turn up the Y LEVEL to full. If you have a 'scope then
adjust BAL2 until the signal seen at the output socket is minimised as much as possible. It will
not go away completely. If you haven't got a scope then use your ears with your monitoring
amp turned up somewhat. Adjust BAL2 until the sound from the output socket is at its
smallest level. You will not get rid of it completely, the ring modulator is not perfect and as
such it will leak or bleedthrough. Once you have done this remember to turn your amp down if
you have turned it up high.
GAIN:
Ensure that the Y LEVEL is set to minimum, but the other two pots to their
maximum. Insert an audio signal into IN X (DC) and adjust GAIN so that the output signal is
at the same level or volume as the input. That is, if you have a 5V peak signal inserted into IN
X, then you should adjust GAIN for a 5V peak signal at the output.
Once that is completed the unit is ready to be used to make music, or just daft noises...
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