24 db/oct filter schematic

[jorgen.bergfors at idg.se]

Sorry, I just saw that you had already explained why you used different capacitors. I have been very busy and haven't had time to read all posts.
Anyway, I'm sure that the design you have chosen make the resonance peak less narrow. Maybe the best solution would be to use four identical capacitors but use two exponential converters, each connected to two stages. Then you could voltage control the spread of the poles. Might be worth a try, while you're at it.

/Jorgen