IF101 2Q/4Q
ELBY Designs - Laurie Biddulph
9 Follan Close, Kariong, NSW 2250, Australia
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Calibration
This circuit requires balance adjustments for each mode (2Q/4Q) and an overall gain adjustment.
Adjust the X balance
1. Set [MODE] to [2Q].
2. Set the [BIAS] knob fully counter-clockwise.
3. Turn the [X LEVEL] knob fully counter-clockwise.
4. Turn the [Y LEVEL] knob fully clockwise.
5. Set [Y IN] to ’AC’
6. Connect a 200Hz 10VAC triangle wave to [Y IN].
7. Adjust P202 for minimum output.
Determine the bias threshold
1. Set [MODE] to [2Q].
2. Turn the [Y LEVEL] knob fully counter-clockwise.
3. Turn the [X LEVEL] knob fully clockwise.
4. Connect a 200Hz 10VAC triangle wave to [X IN].
5. Adjust the [BIAS] knob to just below the point where the VCA starts to turn on. This is called
the "threshold point".
Adjust the Y balance
1. Leave the [BIAS] control at the "threshold point".
2. Set [MODE] to [4Q].
3. Turn the [Y LEVEL] knob fully counter-clockwise.
4. Turn the [X LEVEL] knob fully clockwise.
5. Set [X IN] to ‘AC’
6. Connect a 200Hz 10VAC triangle wave to [X IN].
7. Adjust P203 for minimum output.
Adjust the gain
1. Leave the [BIAS] control at the "threshold point".
2. Set [MODE] to [2Q].
3. Set [X IN] to ‘AC’
4. Set [Y IN] to ‘DC’
5. Turn the [X LEVEL] knob fully clockwise.
6. Turn the [Y LEVEL] knob full clockwise.
7. Connect a 200Hz 10VAC triangle wave to [X IN]
8. Connect 5VDC to [Y IN]
9. Adjust P204 for an output of 10VAC.
