great thanks for the help! that seems to work swell.... attached is the revision.
how would one go about generating / calculating the coefficients in pd using [expr]? then instead of having each in its own message the coefficients could be calculated automatically via global/local sample rate, normalizing gain could be applied/adjusted in real-time, etc. m On Wed, Oct 15, 2014 at 7:59 AM, katja <[email protected]> wrote: > The syntax for biquad~'s arguments, according to the help patch: > > fb1 fb2 ff1 ff2 ff3 > > In the patch you swap fb2<>ff2 and ff1<>ff3. The syntax in the help file > is confusing. For better consistency it could be called: > > fb1 fb2 ff0 ff1 ff2 > > Fill the coefficients for the 44.1 reproduction filter as mentioned in the > musicdsp topic: > > -0.721892 -0.186052 1 -1.70072 0.702938 > > But this doesn't seem to produce a minimum phase filter, and it can't be > inverted. I guess the signs of feedback coefficients must be flipped to > match Pd's biquad implementation: > > 0.721892 0.186052 1 -1.70072 0.702938 > > This gives a frequency and phase response much resembling the plots on > http://jiiteepee.tripod.com/riaa.html. This filter can be inverted by > swapping the feedback and feed forward coefficients and also flipping the > signs: > > 1.70072 -0.702938 1 -0.721892 -0.186052 > > This gives the exact inverse frequency and phase response. > > Katja > > > On Wed, Oct 15, 2014 at 12:14 AM, me.grimm <[email protected]> wrote: > >> all the biquad talk had me remember trying to figure out the riaa filter >> for vinyl playback/production a couple years back which i never quite >> figured out. attached is what I had attempted. >> >> the playback filter seems to be correct but when I switch to the >> production filter. which should be the inverse of the playback filter, i >> get nothing but I think im swapping the coefficients incorrectly... >> >> anyway, here is the thread this is based off of: >> >> http://www.musicdsp.org/showone.php?id=122 >> >> and here is some help on the inverse: >> >> http://music.columbia.edu/pipermail/music-dsp/2003-February/055408.html >> >> maybe someone can make heads or tails of this and give me a help? >> >> basically I am attempting to 3d print a record cutting head so I mostly >> need the production (iRIAA) filter as I will be going straight from PD to a >> record lathe. >> >> thanks! >> m >> >> ps. this was helpful too http://jiiteepee.tripod.com/riaa.html >> >> _______________________________________________ >> [email protected] mailing list >> UNSUBSCRIBE and account-management -> >> http://lists.puredata.info/listinfo/pd-list >> >> >
snd.eq.riaa~-help.pd
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snd.eq.riaa~.pd
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