[sdiy] AC coupling caps on MS20 clone

[David G. Dixon]

> Cumulative DC offset in the signal path would be a reason for me to want
> optional AC coupling in an input.

That's easy enough to do.  I was actually more interested in the possible
requirement of a cap between the HP and LP sections of the filter...?  It
seems to me that HP filters can introduce DC bias to the signal.  Am I
smoking crack?  If a filter cap is used up front, would another one be
required in the middle, or at the end?

> Value/type?
> Combined with input impedance, the coupling cap forms a high-pass filter.
> The value depends on the lowest frequency you want to pass.
> For example, a 0.1 uF cap coupled to a typical 100K input impedance will
> cut-off frequencies at 16Hz and lower.
> Most any non-polar type ought to work.

Yes.  I usually use 474 (0.47uF) Z5U ceramic caps from Epcos for this
purpose.  I guess this would preclude using the filter as a sine LFO.