Julius, Thanks for the quick response! Brilliant, I'll give that a try.
For the record, my starting point _was/is_ `fb_fcomb` (floats), not `fb_comb` (ints) But I'll see if the interpolation helps things. The other thing I was considering was a "post-signal" `ff_fcomb` on the resonant peak pitc and its harmonics, one with a negative coefficient to dampen/negate the original (i.e. comb troughs on a certain pitch instead of comb peaks). It was promising, did help a bit, but wasn't perfect. Now I'm wondering if what you're proposing isn't somehow mathematically related to that. Cheers, Aaron Krister Johnson Music, etc.: https://soundcloud.com/aaron-krister-johnson https://soundcloud.com/filtercreed https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg https://aaronkristerjohnson.bandcamp.com/ http://www.untwelve.org Code: https://github.com/akjmicro <http://www.untwelve.org> On Mon, Nov 18, 2024 at 2:02 PM Julius Smith <julius.sm...@gmail.com> wrote: > Hi Aaron, > > This is a well known phenomenon. It happens when the period is almost an > exact integer. > I see that fb_comb is defined as > > fb_comb(maxdel,N,b0,aN) = (+ <: de.delay(maxdel,N-1),_) ~ *(-aN) : !,*(b0) > : mem; > > You really should use at least > > fb_fcomb(maxdel,N,b0,aN) = (+ <: fdelay(maxdel,float(N)-1.0),_) ~ *(-aN) : > !,*(b0):mem; > > which linearly interpolates the delay. That will still "buzz" when SR/f0 > is an integer. > To address that, try changing fdelay to fdelay4: > > fb_f4comb(maxdel,N,b0,aN) = (+ <: de.fdelay4(maxdel,N-1),_) ~ *(-aN) : > !,*(b0) : mem; > > and if that sounds good, you can try fdelay3 or fdelay2 to reduce > computation. > > Cheers, > Julius > > On Mon, Nov 18, 2024 at 10:29 AM Aaron Krister Johnson <akjmi...@gmail.com> > wrote: > >> Sorry for the fat-fingers in the original post; wrote quickly on my tiny >> phone keyboard... >> >> On Mon, Nov 18, 2024, 11:24 Aaron Krister Johnson <akjmi...@gmail.com> >> wrote: >> >>> Hi all, >>> >>> Perhaps Julius O. Smith or some expert in filter resonance knows the >>> answer: >>> >>> I have an app I built using the Karplus-Strong example in one of the >>> "getting started" tutorial. It uses fi.fb_fcomb at its heart -- a comb >>> filter excited by a burst of noise, then allowed to resonate and decay like >>> a string. >>> >>> It is an _awesome_ sounding "superclav" as I call it; I have been >>> playing Bach on it, it is expressive and its character is super-perfect for >>> Baroque music. >>> >>> My issue is: I have set up a well-twmpered 12-note gamut using a >>> waveform table, it works really well. But for some reason, at SR=48000, >>> every C-sharp in my gamut, regardless of octave played, has an extra bit of >>> bright "ping" that makes it stand out from the others. I suspect that >>> particular pitch somehow reinforces, in the combo filter, some resonance >>> mode and its harmonics. >>> >>> Does anyone have any ideas on how to mitigate and work around this? I >>> have tried post-EQing the signal, but it's tough to do it for each >>> harmonic, and it ends up doing the reverse: making each C-sharp, if the >>> band-reject EQ resonance is narrow enough, sound too "pinched". >>> >>> Perhaps I need to shift my overall gamut by some constant so that no >>> pitch hits the resonance peak? That's not ideal, though, so I am wondering >>> if perhaps it's possible to mitigate this by pre-filyering the noise burst >>> or similar, in such a way that the peak gets reduced on the excitation-end >>> of things. >>> >>> Any/all ideas here are appreciated, and thanks again to the wonderful >>> devs for giving us this powerful tool. >>> >>> -Aaron >>> >>> _______________________________________________ >> Faudiostream-users mailing list >> Faudiostream-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/faudiostream-users >> > > > -- > For language models, Wittgenstein is right: "The limit of language is the > limit of the world" >
_______________________________________________ Faudiostream-users mailing list Faudiostream-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/faudiostream-users
