[PD] butterworth/chebyshev/etc in biquad?

[Alexandre Torres Porres]

"I'm not sure how much difference it makes for low-order filters (biquad
has 2 poles and 2 zeros).  The differences really matter more for higher
order filters, say 8 poles or more..."

That's really relevant information, thanks :)

> I'd just use the ones already made in iemlib...

Sure, but it's more of theoretical doubt and concern. I just wanna learn
more about it, even if I just use what's there in iemlib.

> There's also a 3rd order BW in the docs

Sure, I know about them and I'm studying it. And I'm also now checking
http://msp.ucsd.edu/techniques/latest/book-html/node145.html

I assume it's a matter of how to calculate the coefficients for you to get
filters that are butterworth/chebyshev/etc, and the text from miller point
to how to get butterworth coeficients. But it doesn't point to how to get
Chebyshev 1 pr 2, Eliptic, Bessel and whatever. Any hints?

And I still wonder what's the kind of filter from objects like [lop~],
[hip~], [bp~], [lores~] and [reson~] for instance (cause I know how to get
those with biquad coefficients). And also about the filters described at
"Cookbook formulae for audio EQ biquad filter coefficients"
http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt

Do any of you know what kind of filter it is?

Thanks


2014-12-15 13:59 GMT-02:00 Frank Barknecht <fbar at footils.org>:
>
> Hi,
>
> On Mon, Dec 15, 2014 at 03:41:45PM +0000, Claude Heiland-Allen wrote:
> > On 15/12/14 14:49, Alexandre Torres Porres wrote:
> > >Do any of you know if they're Butterworth or what?
> >
> > I'm not sure how much difference it makes for low-order filters
> > (biquad has 2 poles and 2 zeros).  The differences really matter
> > more for higher order filters, say 8 poles or more...
> >
> > You could waste time calculating coefficients for a biquad cascade
> > (the process is quite involved - see the mkfilter package online),
> > but I'd just use the ones already made in iemlib...
>
> There's also a 3rd order BW in the docs, if you're interested in the inner
> workings: 3.audio.examples/H13.butterworth.pd
>
> Ciao
> --
>  Frank Barknecht                                     _ ______footils.org__
>
> _______________________________________________
> Pd-list at lists.iem.at mailing list
> UNSUBSCRIBE and account-management ->
> http://lists.puredata.info/listinfo/pd-list
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20141215/cba86922/attachment.html>