Quick Input & Output balancing
ADJUSTING INPUT & OUTPUT BALANCE QUICKLY
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Adjusting the Input and Output balance can be frustrating trying to match resistances by measuring one side at a time.
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To complete this in ordeal accurately, in seconds I have made a simple NULL point system for a few dollars.
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The system uses a simple Wheatstone bridge.
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PARTS
Small project box
2 x 2.3k (approx.) closely matched resistors
2 x RCA sockets or RCA plugs on leads
2 x 2mm sockets for multimeter probes
On/Off switch
1.5v battery
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You will be measuring VOLTAGE not resistance.
STEPS
1. Remove all signal cables from your S/C
2. Power up your S/C
3. Measure the resistance across one of your selected input RCA sockets and adjust the volume control so that the resistance measures between 15k and 20k. Don't touch it again until you have finished your adjustments.
4. Connect some interconnects between S/C input or output and your new NULL box RCA sockets.
5. Set your digital multimeter to read VOLTS and place probes in the probe sockets on the NULL box.
6. Adjust the trim potentiometer of the selected channel until the voltage on your multimeter until it is reading ZERO.
7. REPEAT this with each input and the output RCAs.
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NOTE: If you can't reach the NULL point, measure and compare the left and right inputs or output resistance and adjust the trimpot so you start your NULL test with similar resistances.
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