AC-Coupled module inputs

[John Blacet]

I think the whole concept of capacitive coupling in the input and output
of AC devices was mainly to eliminate the rather large DC components
that were present in some older technologies. Modern, low offset op amp
circuits probably have less need for caps. 

The other factor in eliminating caps is the audiophile view that the
dissipation factor of the commonly used electrolytic has a noticeable
effect on audio quality. A better cap to use might be a metallized
polypropylene. We use one of these in the KW. The downside of these is
that they are fairly large and a bit expensive. If you can get away with
using one on the input and nothing on the output, you may be sonically a
bit ahead.

For some devices producing single frequency waveforms, such as VCOs, the
distortion caused by the output cap is of less consequence.

Just my $.02.
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Regards.
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John Blacet
Blacet Research Music Electronics
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blacet at metro.net
http://metro.net/blacet/music.html