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It's a high pass filter, not a low pass filter

" Above the "corner frequency" of 2Hz, the AC voltage will fall off at about 20dB per decade, so roughly 20dB down at 20Hz."

You're looking at the filter upside down. It's not a low pass filter blocking everything above 2Hz. It's a high pass filter intended to pass the audio band without affecting it.

It's a high pass filter with a corner frequency of 2Hz. So below 2Hz the AC voltage will fall off at about 20dB per decade, so at roughly 20db down at .2Hz but we need to look at what happens ABOVE of the corner frequency.

So once again, to get out of the affects of a high pass filter you need to go a decade up in frequency from the corner frequency. At that point the attenuation and the phase shift has stopped.

From the corner frequency (-3db point) if you go one octave up there is only 1db attenuation left but to get beyond all the attenuation you have to go up a decade from the corner frequency.

So at that frequency point the filter is not causing AC across the cap but other things like ESR would be.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"


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