[music-dsp] Orfanidis-style filter design

[david.lowenfels at gmail.com]

I have the PDF. The cool thing about this paper which is not mentioned in the abstract is the least-squares fit to the spectrum magnitude of an arbitrary 2-pole filter, giving a very nice biquad with no need for oversampling to get a good nyquist response. I have some matlab/octave code for this somewhere... I made an EQ using this many years ago.

-D


On Nov 27, 2011, at 2:29 PM, robert bristow-johnson wrote:

> On 11/27/11 3:17 PM, Dominique Würtz wrote:
>> 
>>>>   Any ideas?
>>>   Knud Christensen "A Generalization of the Biquadratic Parametric"
>>>   http://www.aes.org/e-lib/browse.cfm?elib=12429
>>> 
>> Hmm, reading the abstract I'm not 100% sure if it really addresses what
>> I'm aiming at. Sorry for being sceptical, but before I shell out 20$ for
>> this, can you confirm me that it actually considers the gain correction
>> at Nyquist?
>> 
> what it does is inverse-map the 5 coefficients of the biquad filter to 5 parameters that users might find useful.  there *are* only 5 degrees of freedom, so it really is only an issue for how you want those 5 control knobs defined.
> 
> why not put out a request for anyone here at music-dsp who has free access to the full AES archives (i don't, sorry) to send you the pdf?  maybe there is a similar paper by the author living out there in the internet.  maybe you can find and contact the author.  i have a paper copy of the preprint *somewhere*, but i am not sure where.
> 
> L8r,
> 
> -- 
> 
> r b-j                  rbj at audioimagination.com
> 
> "Imagination is more important than knowledge."
> 
> 
> 
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