oh sure, but that's more like a slew or glide and you don't go down to zero anyway :)
and if you're filtering audio, you don't want to keep inaudible stuff. All I'm saying is that if you are soing this to fade to slience you need a DC filter Em sex., 12 de abr. de 2024 às 04:12, cyrille henry <c...@chnry.net> escreveu: > I don't think it's weird for a lowpass filter to go under 20Hz. They are > not restricted to audio signals. > I use them a lot to smooth control signals, or to replace line~. > (I really hate line~ to control sound amplitude or preset transition, it's > way too robotic) > > cheers > c > > Le 12/04/2024 à 08:01, Alexandre Torres Porres a écrit : > > and you got a strong DC component over there :) > > > > anyway, it also seems weird to have a lowpass or a bandpass going as low > as in the 20hz range. If you wanna do it just so it fades out to silence, > you need a DC filter, something like a [hip~ 5] object, so when the > lowpass, bandpass gets there, then you have nothing. > > > > cheers > > > > Em qui., 11 de abr. de 2024 às 15:40, Antoine Rousseau < > anto...@metalu.net <mailto:anto...@metalu.net>> escreveu: > > > > Well, let's simplify a bit, forget all the filter complexity (Q, > slope, definition of the cutoff frequency...). > > > > Let's just say that the output of a lowpass filter cannot move > faster than the cutoff frequency: a 1Hz filter output cannot move faster > than 1Hz (so it can't go back and forth in less than a second or so), a > 1kHz can't go back and forth in less than about 1ms, etc. The output of a > 0Hz filter can't move... at all. When you set the cutoff to 0Hz, the output > freezes to its current value. It won't magically decay to 0. > > > > Hey, if you set the framerate of a movie to 0 frame/second, it will > just stop, and will show the same image forever; it won't fade to black! > > > > Antoine > > > > > > > > Le jeu. 11 avr. 2024 à 14:08, Peter P. <peterpar...@fastmail.com > <mailto:peterpar...@fastmail.com>> a écrit : > > > > * Antoine Rousseau <anto...@metalu.net <mailto: > anto...@metalu.net>> [2024-04-11 13:40]: > > > That doesn't seem incorrect to me; after all, a lowpass > filter at 0Hz > > > implies that its output is constant (any change would involve > frequencies > > > > 0Hz). > > > > Thanks Antoine, > > > > Why does a lowpass filter, that has a cutoff frequency of 0Hz > imply that > > it's output is constant? > > > > I will describe the problem again hoping that I will understand > it > > better myseld: > > I have an oscillating input signal that has some DC offset > (unipolar > > sawtooth from phasor~). I fade this signal's amplitude to -inf > dB using > > [line~]. > > > > I also fade down the filter cutoff (defined as the -3dB point of > the > > filter curve) from 400Hz to 0Hz. The filter will then continue > to produce an > > non-decaying output. > > > > If I fade down the filter cutoff down to only 1Hz, it's output > will decay (somehow > > counterintuitively to me). This is the part I don't get. > > > > I understand that vcf~ is a resonant filter, and it can have a > gain > > greater 1 around the cutoff frequency, especially for high Q > values. The > > above behavior can also be observed for Q=1. > > > > Thanks for all hints! > > Peter > > > > > > > > _______________________________________________ > > Pd-list@lists.iem.at <mailto:Pd-list@lists.iem.at> mailing list > > UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list < > https://lists.puredata.info/listinfo/pd-list> > > > > _______________________________________________ > > Pd-list@lists.iem.at <mailto:Pd-list@lists.iem.at> mailing list > > UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list < > https://lists.puredata.info/listinfo/pd-list> > > > > > > _______________________________________________ > > Pd-list@lists.iem.at mailing list > > UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list > > > > _______________________________________________ > Pd-list@lists.iem.at mailing list > UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list >
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