why don't you use then filtergraph~ to get all biquad coefficients? you can specify both F and Q and it will feed your biquad with the required list of coeffs.
I tried it of course, but the shape of the original bandpass filter in [filtergraph] is not what I am looking for. It's too complicated, the curve has at least three very significative courbure change points (it looks looks like a gaussian curve, with a "fat" base). The quality factor is only significative over -3 dB ! This means that too many frequencies are kept, even if you raise Q. This makes this filter almost "wha-wha" sounding (or too much "resonant"). I assume most electronic musicians like this "analogue" sound.
I personnaly only want a quasi-spike (or isoceles triangle, if you prefer), and no resonance nor wha effect. I know the actual curve will be a bit concave, but that's not a problem actually.
Any links to (free) external filters or abstractions related to filters under MSP ? Why didn't they use [vcf~] instead of [reson~] ?
I still wonder why there are no conversion formula on the Internet. I think I will get into the equations directly to solve it myself (maybe using Scilab). Has anyone got into it there ?
On Tue, May 18, 2004 at 12:35:40AM +0200, julien.breval@tremplin-utc.net wrote:
Selon Frank Barknecht fbar@footils.org:
Hallo, julien.breval@tremplin-utc.net hat gesagt: //
julien.breval@tremplin-utc.net
wrote:
The right solution sould be to use [biquad~]. MSP-[biquad~] looks
like
Pd-
[biquad~] with some arguments inversed. Unfortunately, besides a paper from Harmony Central I didn't find much
information on it. Do you know any documentation about biquad filters
?
Guenther wrote a set of externals to assist in biquad~ filter design. See externals/ggee/filters on the CVS at pure-data.sf.net
Thanks, I will have a look at it
actually, all I need is some basic conversion information from (F, Q) to
the
the parameters of [biquad~]
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