[sdiy] Filter topology: n-order == n-poles?

[Amos]

I can see such a drastic filter being useful for scientific audio
filtering, but it might lack a certain musical flexibility.  Maybe if
you are creating some sort of physical-modelling patch or other
esoteric modular manipulations... I'm glad to see such a thing just
for the sake of having options. :-)

On 1/19/07, HL-SDK Synths <syntroniks at gmail.com> wrote:
> On the general topic of filters... It seems to be popular opinion that
> filters that have more than 4 or 6 poles don't sound too musically good. I
> haven't heard any, but doepfer may be making a switched-capacitor filter
> with -30db/oct and -60db/oct but they say the -60 wasn't really useful for
> audio...
>
>
> On 1/19/07, Amos <controlvoltage at gmail.com> wrote:
> > Hello,
> >
> > I am reading Timothy Stinchcombe's analysis of the Korg MS-10 and
> > MS-20 filters, and was reminded of a question that's been in the back
> > of my mind for a little while.  Filter users typically refer to a
> > filter's number of poles, where each pole seems to add -6dB/Octave to
> > the cutoff slope.  Filter designers and mathematical types tend to
> > refer to the "order" of the filter, e.g. "2 cascaded, buffered
> > 1st-order sections" in the Korg MS filters.  Is a 2-pole filter
> > necessarily a 2nd-order filter, or is the relationship more
> > complicated?  Thanks for answering this rather basic question...
> > thanks!
> >
> > -Amos
> >
>
>