Hi James, Glad you worked it out!
One useful rule of thumb is that the Q is roughly the decay time in periods. Here is most everything I know about Q, including a derivation of that tidbit: https://ccrma.stanford.edu/~jos/filters/Quality_Factor_Q.html Cheers, Julius On Sat, Oct 31, 2020 at 7:03 AM James Mckernon <jmcker...@gmail.com> wrote: > In time-honoured fashion, I worked out an answer to this one shortly > after posting to the list. I found a way to get a q value for resonbp > from a decay time. My expression, which I got by inverting an > expression I found for decay time in terms of q, is as follows: > > q(decaytime) = freq / (1 - exp(log(0.001) / (decaytime * ma.SR))) * > ma.PI / ma.SR; > > Comments and other solutions (particularly mind-expanding ones) still > welcome. > > On 10/31/20, James Mckernon <jmcker...@gmail.com> wrote: > > Hi all, > > > > My filter theory isn't very good; perhaps a filter-savvy faust user > > can help me out. > > > > I'm seeking a filter in faust analogous to Ringz in supercollider ( > > https://doc.sccode.org/Classes/Ringz.html ); that is, a filter whose > > impulse response is a sinusoidal oscillation at a given frequency, > > decaying over a given length of time. > > > > I suspect that fi.resonbp can do such a thing, but I couldn't work out > > a scaling that would let me provide a decay time in seconds and > > convert this to a Q for resonbp. (I tried plugging in tau2pole, but to > > no avail.) > > > > What would be the easiest way to construct such a filter in faust? > > Suggestions welcome. > > > > Many thanks, > > James > > > > > _______________________________________________ > Faudiostream-users mailing list > Faudiostream-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/faudiostream-users > -- "Anybody who knows all about nothing knows everything" -- Leonard Susskind
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