What resistor and potentiometer values for GC shunt volume control? What resistor and potentiometer values for GC shunt volume control? - diyAudio
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What resistor and potentiometer values for GC shunt volume control?
What resistor and potentiometer values for GC shunt volume control?
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Old 19th September 2007, 07:27 PM   #1
sharpi31 is offline sharpi31  United Kingdom
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What resistor and potentiometer values for GC shunt volume control?
Default What resistor and potentiometer values for GC shunt volume control?

I have a modified dac-ah (8xTDA1543 with passive I/V) connected to a Peter Daniels LM3875 kit.

I believe the input impedance of the amp is about 18.5Kohm (?). The passive I/V resistor in the dac is 150R. I get about 1Vpp from the dac.

I have been using a PEC 1meg pot with 39Kohm resistor in fake law configuration. The sound is great, but the pot doesn't track evenly at the start of the rotation and the volume comes in very quickly so it is impossible to get a satisfactory channel match at low listening levels.

I picked this attenuator to work with my previous single TDA1543 dac which also had passive I/V but with a much higher output impedance. Now I have the 8 dacs running in parallel, I feel ready to change to a different attenuator configuration which gives better low level channel matching and lower input impedance.

What would be the best passive attenuator configuration to try? I am tempted to go with a 10Kohm series resistor and log pot in shunt position, but have no idea what value of pot would be best.

Or would another setup be preferable?

Any advice would be much appreciated :-)
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Old 20th September 2007, 03:02 AM   #2
Leolabs is offline Leolabs  Malaysia
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Old 20th September 2007, 07:23 AM   #3
sharpi31 is offline sharpi31  United Kingdom
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What resistor and potentiometer values for GC shunt volume control?
Excellent - thanks Leolabs :-)
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