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Differential amplifier mystery?
Differential amplifier mystery?
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Old 7th March 2006, 02:07 PM   #1
klitgt is offline klitgt  Denmark
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Location: Denmark
Default Differential amplifier mystery?

In my Denon DCD3560 that has been modified with a bypass of the low pass filter , there is a strange configuration around the differential amlifier opamp (IC512) that takes together the half-cycle signals from the 2 DACs and associated I/V converters (IC511/509) in one channel. Same situation in the other channel.

Between each of the I/V converters (IC511/509) and the differential amplifier opamp IC512 is a voltage divider R540 (4k3) and R541 (2k2), that couples to ground and is paralleled with C530 (820p). This voltage divider "looks" into the non-inverting input of IC512.

Into the inverting input of IC512 is another voltage divider R539 (4k3) and R542 (2k2), that couples to the output of IC512 and is paralleled with C529 (180p).

I would like to know why C520/C530 have different values, they are in similar positions in similar functions?

BTW the output is quite high with this mod, but it takes away some og the mud in the sound and makes it better defined and gives more resolution.

If I want to reduce the output I suppose I can change the resistor values of the above voltage dividers to e.g R540 to 5k6 and R541 to 1k5 ?
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