Nice sleuthing Holmes On Tue, 29 Jan 2019 at 01:43, Alexandre Torres Porres <por...@gmail.com> wrote:
> I guess "bingo"? > https://ccrma.stanford.edu/~jos/pasp/First_Order_Delay_Filter_Design.html > > Em seg, 28 de jan de 2019 às 22:54, Alexandre Torres Porres < > por...@gmail.com> escreveu: > >> >> Em seg, 28 de jan de 2019 às 18:45, Peter P. <peterpar...@fastmail.com> >> escreveu: >> >>> * Alexandre Torres Porres <por...@gmail.com> [2019-01-28 20:10]: >>> > I guess I'm figuring something out, but the secondary inlets are still >>> not >>> > clear to me, they set the decay time, but why is there a "low" and >>> "high"? >>> Could it be that decay times are different for high and low frequencies >>> and that these two are divided by a cutoff frequency? Just guessing.... >>> >> >> Sort of... I finally made some sense of the code. it seems there's a >> 1pole filter whose parameters depend on these low/high values and the delay >> length! In the comment of the code we find a filter equation, something >> like:* "yn = (2*gl*gh ) / (gl+gh) x + (gl-gh) / (gl+gh) y[n-1]" *- >> where *gl* & *gh* are derived from these low and high values. Here's a >> code simplification of it >> >> >> >> *for*(i = 0; i < x->x_ctl.c_order; i++){ >> >> gl = pow(10, -0.003 * x->x_ctl.c_length[i] / low); >> >> gh = pow(10, -0.003 * x->x_ctl.c_length[i] / high); >> >> x->x_ctl.c_gain_in[i] = 2*gl*gh / (gl+gh); >> >> x->x_ctl.c_gain_state[i] = (gl-gh) / (gl+gh); >> >> >> >> I don't really get how this filter fully works yet, but I can sort of get >> the gist of it. I'm now in the quest to find what is the source of this >> filter, and maybe try it out independently to see how it behaves. But >> perhaps a more sophisticated method, with a settable crossover frequency >> could be used instead. >> >> >> And yeah, it seems vanilla's [rev2~] and [rev3~] are implementations of >> feedback delay networks like it's been said here on this thread. >> >> >> cheers >> >> >> >> >> > _______________________________________________ > Pd-list@lists.iem.at mailing list > UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list >
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