Tapped 4pole et al.

[jh]

>I've
>never simulated the 3320 or 3080 style filters because (of course) the models
>don't exist for EWB. I saw JH's model for the 3080 but I don't understand all
>the parameters. 

This was a simplified model for the free evaluation version of PSpice, therefore
I used mathematical blocks that don't "count" as active components.
But I'd say you can create a decent OTA model in *any* Spice program that
doesn't have restrictions in component count by just drawing the internal circuit
with a handful of garden variety transistors. You won't get accurate noise, offset
and gm variation results of course, but you will get the basic behaviour including
the major nonlinearities. 
I always see this in my day job, too: people want "accurate models" and give in 
early when the don't get them. I say make your own model and understand where
its limits are, and you will have a non-perfect but still highly useful model.

JH.