"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@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__

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