[sdiy] Book on analogue filter design

[Colin f]

> I've decided to attack the problem of the weedy sounding filter on my
> Jupiter-6, and I'm looking for a book on analogue filter design to get
> me up to speed on the different types - state variable, transistor
> ladder, diode ladder, OTA, etc. Does anyone have any recommendations?

I don't think you need a book really, just pick a filter you like the sound
of, and work out how to graft it in there.

Th JP6 filter is a pair of SVFs in series, built from Roland IR3109 ICs.
You could extract these chips, plus a few other components around them, and
replace them with a header connection to give you the necessary filter
cutoff and resonance CVs, audio in and out, filter mode select and power
connections.
Then design a little daughterboard to re-use your IR3109s in the cascaded
integrator design used in the JP8.
It'll be very tricky to do this in a way that allows you to close the lid on
the JP6 though.
Doing it all 6 times is going to be a lot of work.
I was planning to do this with my JP6, but I bought a JP8 and sold the 6
instead - which was much easier.

Cheers,
Colin f