[sdiy] filters, state variable in particular

[Paul Schreiber]

>I just happened across a magazine article that among other things talked about
> the state variable filter,  and was wondering how useful that circuit would
> be in the SDIY context.  Comments?


The term 'state variable' refers to solving the differential equation for the 
output transfer function using algebraic substitution :)

Not the fact the filter 'varies'. It has to do with the filter 'topology'. A 
good example: Oberheim SEM filter.

Paul S.