[sdiy] Multi-Input filters

[jhaible]

> I'd suggest you to check (translate) this Japanese site
> first.
>
> List of topologies and devices for VCFs:
>
>   http://www.asahi-net.or.jp/~wz4k-tnk/kairo/vcf3.html
>
> I can't find errors easily.
>
> In this Mr. Tanaka's site, some explanations about VCFs
> are updated.  Theories of Korg35 style filter and the
> transistor ladder filter are added last year.  There
> may be some other additional updates.
>
>   http://www.asahi-net.or.jp/~wz4k-tnk/kairo/vcf.html
>

Awsome web site indeed!
This gave me inspiration for my JH-720 project, and the PS-3200
clone would not have been able without it either.

Theory of Korg35 filter: I just saw there is some new (Japanese)
text, referring to voltages and currents in a drawing of the 2-transistor
core.

Sam, as you're speaking Japanese and I'm not: Is there new information
about how this actually works? (Of course the transistors act as VC
resistors, but *how* they do this is still beyond me, and beyond
every industrial analog ASIC designer I've asked so far. )

Best Regards,

JH.