[db filters?]

[jhaible]

> I wonder if a VC switch that selects which of the various filters in your
> unit/rig/modular is currently running would be worth my time. I s'pose I
> coule just use a footswitch...ah welll.

A VC Switch would only be a compromise. What you need is a VC
*crossfade* (or "scan") over several VCF outputs. For further information, 
look for the "JH-4" section on my homepage:

http://www.it.kth.se/~e93_mda/synths/friends/haible/hj_jh4.html

There is a block diagram at 

http://www.it.kth.se/~e93_mda/synths/friends/haible/h4_vca_block.gif

and the schematics for the section named "scanner1" in the block diagram
is here:

http://www.it.kth.se/~e93_mda/synths/friends/haible/hj_vcfsc.gif

And there's the good old universal Interpolating Scanner, of course,
but the simple circuit from hj_vcfsc.gif does the job. Basically just
a handful of transistors and carefully selected resistors.

Last (sorry for the shameless advertisment), you can hear such
crossfades over several filters on my CD:

http://www.it.kth.se/~e93_mda/synths/friends/haible/hj_cd1.html

The JH-4 is most prominent on Track 8, "Media In Vita".
For a short impression of how smooth such a crossfade can
sound, you can download a short sample from Track 9,
"Die Grosse Genesung":

http://www.it.kth.se/~e93_mda/synths/friends/haible/hj_adl3_genes.mp3

The filter sweep right at the beginning is not very spectacular (the
wild stuff is in track 8), only that it actually is *no* filter sweep. I
used
a filter bank (EMS filter bank clone) with *fixed* filters and made a
crossfade (or "scan") over the various filter outputs.

JH.