[sdiy] Steiner VCF topology - anyone DC couple?

[Aaron Lanterman]

Hi gang,

For those who have built the Steiner VCF in it's various incarnations -
are the inputs always AC coupled in your various incarnations?

The reason I ask has to do with the way you can get different responses by
putting the input into different parts of the circuit. The way it's shown
in Steiner's original article, there's a distinct switch; but I've seen
commercial ones for sale, and other DIY renditions, where you can plug
into the HP, LP, and BP inputs simultaneously and do neat things.

The trick is that the analysis of the circuit changes if those inputs are
AC coupled (plugging in a zero signal has the same effect as opening
that input) compared to DC coupled (plugging in a zero input effectively
grounds that input, instead of leaving it open, making my analysis more
messy).

Just curious about that.

There may also be some other subtlety I'm missing - in which case,
please let me know...

- Aaron

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