Xpander VCF

[>>>marjan<<<]

Hi all,

I was looking at OB Xpander's VCF on Grant's page, and while I
understood
theory of different filter modes, I can't figure out cap values used.
In most of the quad OTA filters (CEM,SSM,13700) caps used are all the
same value and in range 100p-1n (integration cap that is), and Xpander
has 33n caps for first 3 stages (first stage can be switched "off" with
100p cap needed for some modes) which seems too high, and fourth stage
has 100 times smaller 330p cap. Why's that? And why so large caps?

Cheers,


marjan