opinions needed

[jh.]

> The real trick, for us DIY'ers, is finding a source for rotary pots that
have
> a center tap.

The real trick is using a scanner circuit (;->)
You can simulate as many taps as you like, and you have voltage control
rather than a manual pot only.
In one synth I have arranged the 3 basic modes LP, HP and BP of a SEM
filter, and the output of an extra 4-pole LPF in that order (with the Notch
automatically generated between LP and HP of course). Sweeping
the cutoff frequency with one ADSR and the filter mode with a second
ADSR is still good for new discoveries ...

Of the static modes of the classical SEM filter, one favorite of mine
is somewhere between Notch and HP, with medium high resonance.
Notch alone is just a slight phasing, HP often cuts away too much bass
(unless the cutoff frequency is so low that the bass is actually boosted),
so this in-between setting is justfit for bright and cutting type of sound.

JH.