>From looking at the helpfile for [phaseshift~], this sounds very much like the all-pass filter from Robert Bristow-Johnson's EQ Cookbook. You can calculate the biquad coefficients for it like this:
w0 = 2*pi*frequency_in_Hz / sample_rate alpha = sin(w0)*sinh(ln(2)/2*Q*w0/sin(w0)) fb1 = 2*cos(w0) / (1+alpha) fb2 = (-1+alpha) / (1+alpha) ff1 = -fb2 ff2 = -fb1 ff3 = 1 .mmb On Sat, Oct 5, 2013 at 12:31 PM, Alexandre Torres Porres <[email protected]>wrote: > > the phase response given in phaseshift's help file suggest otherwise. > > it's more like the response from miller's H14 example... > > So I guess you can have a 2nd order one (lie phaseshift) by putting two of > these together, right? And I suspect it doesn't really need to have > anything to do biquad just for being "2nd order", huh? > > cheers > > > 2013/10/5 Alexandre Torres Porres <[email protected]> > >> Anyway, next on my list is finding out how to implement max's >> [phaseshift~], which is also an allpass filter. There's no Pd clone for it >> so it seems, right? >> >> Well, it doesn't really what it is other than a 2nd order filter. From >> that I could think you can generate it with [biquad~], but the phase >> response given in phaseshift's help file suggest otherwise. >> >> any contributions welcome >> >> thanks a lot >> >> 2013/10/5 Alexandre Torres Porres <[email protected]> >> >>> but this way it won't be the same as cyclone's [allpass~], the way I did >>> it is equivalent to it (and max's). >>> >>> cheers >>> >>> >>> 2013/10/3 Chris Clepper <[email protected]> >>> >>>> You only need one delay line for the allpass. >>>> >>>> feedforward = input * -gain >>>> feedback = delayout * gain >>>> delayin = input + feedback >>>> output = delayout + feedforward >>>> >>>> http://www.spinsemi.com/knowledge_base/effects.html#Reverberation >>>> >>>> >>>> On Thu, Oct 3, 2013 at 11:29 AM, Alexandre Torres Porres < >>>> [email protected]> wrote: >>>> >>>>> i hope i guess i figured it out on how to implement it with delay >>>>> lines. see attachment. And I realize you can't do this with [fexpr~] or >>>>> [biquad~] because the sample delay length is kinda big for that, right? >>>>> >>>>> cheers >>>>> >>>>> >>>>> 2013/10/3 Alexandre Torres Porres <[email protected]> >>>>> >>>>>> cool, but do you know how to implement cyclone's [allpass~] with it? >>>>>> >>>>>> It's really unclear to me what is the relation of this pass filter >>>>>> with the one you can generate with biquad coefficients, or with raw >>>>>> poles/zeros objects for that matter. >>>>>> >>>>>> Well, one way or another, it's also unclear to me how to do it with >>>>>> delay lines. >>>>>> >>>>>> seems that it is related to a comb filter, right? >>>>>> >>>>>> cheers >>>>>> >>>>>> >>>>>> 2013/10/2 Chris Clepper <[email protected]> >>>>>> >>>>>>> Allpass for reverb is easy to do with delwrite~ and vd~. I used 32 >>>>>>> of them today to recreate a famous 'deep space' reverb. >>>>>>> >>>>>>> >>>>>>> On Wed, Oct 2, 2013 at 1:53 AM, Alexandre Torres Porres < >>>>>>> [email protected]> wrote: >>>>>>> >>>>>>>> hi there, i see the biquad's coefficients can be set as an allpass >>>>>>>> filter, generated by frequency and "Q" parameters. But can it do the >>>>>>>> same >>>>>>>> as cyclone's [allpass~] filer? If yes, them how since the parameters >>>>>>>> for >>>>>>>> [allpass~] are different (delaytime and such). >>>>>>>> >>>>>>>> One way or another, I guess that my real question is: how to >>>>>>>> implement [allpass~] from vanilla objects? >>>>>>>> >>>>>>>> thanks >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> [email protected] mailing list >>>>>>>> UNSUBSCRIBE and account-management -> >>>>>>>> http://lists.puredata.info/listinfo/pd-list >>>>>>>> >>>>>>>> >>>>>>> >>>>>> >>>>> >>>> >>> >> > > _______________________________________________ > [email protected] mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list > >
_______________________________________________ [email protected] mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
