[LAU] [LAD] [ANN] CAPS 0.9.12

mark hadman markhadman at googlemail.com
Sun Aug 25 16:51:41 UTC 2013

Hi, thanks for the software!

I'm using Lorenz as a modulation source, but it appears that amplitude
decreases greatly as I slow down the rate. Is there a high pass / DC
blocking filter somewhere in there?

Here's my code, in Supercollider:
{SinOsc.ar(freq: 100 * (2 ** LADSPA.ar(1,1774,0.01,1,1,0,100)))}.play

thanks again,
Mark Hadman

On 25 August 2013 01:00, Tim Goetze <tim at quitte.de> wrote:
> [Fons Adriaensen]
>>On Sun, Aug 25, 2013 at 12:21:52AM +0200, Tim Goetze wrote:
>>> I'm planning to evade this problem by crossfading between two parallel
>>> static filters.  Some phase mismatch issues can probably be expected
>>> when the parameter sweep covers a larger range, but I'm hopeful it
>>> will turn out not to be much of a problem in actual practice, and that
>>> we will find out soon.  It really needs a fix.
>>I doubt very much if that will provide a practiacal solution.
>>The state of the filter depends on signal history. Depending
>>on the parameters, this could be quite long.
> I think the question deciding the quality of the filter fade is, how
> big will the phase difference between the two filters be?  Amplitude
> differences shouldn't matter when we crossfade, as long as we're not
> phase-canceling.
> These are very simple filters that don't take long to settle on a
> stable phase relationship.  A reasonably small parameter change will
> not change their phase response by much, so my expectation is that
> there will be only little cancellation and the fade thus close to
> imperceptible; at most a slight attenuation of high-frequency content.
> Just theorising over a glass of wine though.
>>The simple solution is to smooth the input parameters,
>>limiting their rate of change. Nobody expects an EQ
>>section to change from 100 Hz to 10 kHz in less than
>>half a second (unless it's a synth VCF module, but then
>>you definitely need something else than a biquad).
> Yes, that is a very convenient way to solve it, perhaps the preferable
> one given the realities.
> Tim
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