[sdiy] Question about Arp 4012 vs 4035 VCF sub-modules..

[Jean-Pierre Desrochers]

Checking out some Moog ladder VCF projects
I finally decided not to use ARP's old design
but instead build the following Rick Jansen's VCF version:
http://electro-music.com/wiki/pmwiki.php?n=Schematics.MoogTypeFilter

Only 3 transistors matched pairs involved.
The use of a CA3046 replaces lots of trannies and
as a bonus a section is used to 'oven' the array package
for thermal stability. It also has an improved v/octave
expo generator derivated from the Formant synth project..
I also like the use of 2 x LF412 precision opamps as FET buffers
at the output mix. (Dual matched fets are not easy to find..)
The only drawback is that I'd loved to have a part of this
circuit to compensate for the audio level drop when
resonance is pushed at oscillation.

By the way, what are the differences between LM3046 vs LM3086 ??
J-Pierre