Question - Potentiometer for LM3886 - Page 2

djoffe · 28th January 2012, 02:00 PM

Andrew,

Perhaps we are agreeing...I believe the question was, does the second cap affect treble information in the audio band? In the audio band, the answer is...not much! That's because in the audio band, there's still plenty of loop gain, so not much voltage across the cap. Of course, above the audio band, where the loop gain has dropped, the cap would look like an RF bypass...but that's above the audio band, so there should be a minimal effect in the audio (treble) band.

Does this seem reasonable?

KatieandDad · 28th January 2012, 02:03 PM

MOST sources will have a capacitor in the output leg in order to decouple any DC from reaching the ouput sockets.

Any DC across the pot will result in noise.

The pot needs to be across the input (the furthest left point of your diagram)

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28th January 2012, 02:00 PM	#11
djoffe diyAudio Member Join Date: Oct 2008	Andrew, Perhaps we are agreeing...I believe the question was, does the second cap affect treble information in the audio band? In the audio band, the answer is...not much! That's because in the audio band, there's still plenty of loop gain, so not much voltage across the cap. Of course, above the audio band, where the loop gain has dropped, the cap would look like an RF bypass...but that's above the audio band, so there should be a minimal effect in the audio (treble) band. Does this seem reasonable?

28th January 2012, 02:03 PM	#12
KatieandDad diyAudio Member Join Date: Nov 2011 Location: UK	MOST sources will have a capacitor in the output leg in order to decouple any DC from reaching the ouput sockets. Any DC across the pot will result in noise. The pot needs to be across the input (the furthest left point of your diagram)

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