Subject: Re: [linux-audio-dev] wcnt linear filters
From: Alfons Adriaensen (fons.adriaensen_AT_alcatel.be)
Date: Tue Feb 03 2004 - 16:13:54 EET
On Tue, Feb 03, 2004 at 01:52:13PM +0000, Steve Harris wrote:
> On Tue, Feb 03, 2004 at 02:21:53 +0100, Tim Goetze wrote:
> > ps: the svf sounds better to me with the 'very slight waveshape for
> > extra stability' removed.
>
> Yeah, but without it the filter tends to explode with highish cutoff
> values (above fs/4 IIRC). I should probably move it to doubles and remove
> the waveshape.
Moving it to doubles will not help. The problem is that at high F, the
simple mapping from the continuous time domain to the sampled domain breaks
down. You need to modify the params as non-linear functions of F and Q
in order to correct for this.
(had the same problem with the M**G VCF plugins)
-- Fons
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