Wiardgroup

I should also mention that the Sallen-Key is lambasted in the engineering article, while the 
state variable is praised.

So I guess the point is, the more engineering precise a filter, the less musical it is.

Ironic, eh?

So if you want to clean up shortwave broadcasts to make a voice more intellegible,
use a state variable.

If you want to smack the sucker with a big pulse and get an acoustic sounding audio 
response, use a Sallen-Key.

What they are talking about with limited Q, I have no idea. Sallen-Key filters are resonant 
as Hell.

--- In wiardgroup@yahoogroups.com, "Grant Richter" <grichter@a...> wrote:
>
> The description "state variable filter" refers to a specific filter topology in engineering.
> 
> See: "A Beginner Guide to Filter Topologies"
> 
> http://www.maxim-ic.com/appnotes.cfm/appnote_number/1762
> 
> A state variable filter is the analogue computer simulation of a mass suspended on a 
spring.
> You will find it in all analogue computing books as an introduction to analogue 
computer 
> patching.
> 
> It is literally, the oldest trick in the book.
>