Normally SVFs have a signal input and discrete LP, BP and HP outputs.
The only VCF I’m aware of that is similar to yours in this respect, is a (modified) Steiner Synthasystem/Synthacon filter, and I believe that’s a Sallen-Key topology, not State-Variable.
Whoops, seems that I referred to Sallen-Key filters as a SVF subtype for like.. 8 years?
State variable filter is in fact specific type as now I can see... Thanks for pointing that!
I’m curious, how did you implement LP, BP, HP inputs (...)
It uses four vacuum diodes (2xEAA91) as dynamic resistance element and BP/HP signals are injected into intermediate stages. This is very similar to the Synthacon filter, but output / feedback amplifier is made around double triode (6N3P).
non-Eurorack kit 95USD
(core PCB, tube sockets + tubes, You'll need supply your own PCB parts, jacks, pots, wires and eventual M3 screws for fastening PCB to panel).
Eurorack kit (PCBs + Panel + Tubes + Sockets, without other parts) 125USD I have added this variant since there's a lot of interest
The price for the full Eurorack kit would be 155USD
Fully assembled Eurorack module 270USD
25USD shipping to US
20EUR shipping to EU
I consider making other kit variants. Polish Post can ship this kit worldwide, but costs will be little higher.
Interest list moved to OP.
Leave me PM if you would like to have more custom option. This list is only to clarify current interest