Thanks Christof. The help file for [svf~] shows a control-rate number box feeding the cutoff. But I tested with [sig~] and it works. Thanks.
However I see no mention in the help of [scf~] for how to set Q. Cutoff and Resonance only. -- William Huston: williamahus...@gmail.com Binghamton NY *Public Service Mapping / Videography / Research* Blog <http://WilliamAHuston.blogspot.com> -- Facebook <http://facebook.com/billhuston> -- Twitter <http://twitter.com/WilliamAHuston>-- Youtube <https://www.youtube.com/channel/UCGijK1amWOLglT3YeTyEBNQ?sub_congfirmation=1> Document collections: VirtualPipelines <http://TinyURL.com/VirtualPipelines> -- BHDCSDimockArchive <http://bit.ly/BHDCSDimockArchive> Please support my work: TinyURL.com/DonateToBillHuston On Wed, Apr 25, 2018 at 1:38 PM, Christof Ressi <christof.re...@gmx.at> wrote: > Hi William, > > both [vcf~] and [svf~] let you set the cutoff frequency at audio rate and > both have adjustable Q... what are you missing exactly? > > the vcf_* filters in iemlib are all suited for audio rate modulations. > > for moog style lowpass filters have a look at [bob~] and [ggee/moog~]. > > Christof > > > > Gesendet: Mittwoch, 25. April 2018 um 18:46 Uhr > Von: "William Huston" <williamahus...@gmail.com> > An: "Julian Brooks" <jbee...@gmail.com> > Cc: "pd-list@lists.iem.at" <pd-list@lists.iem.at> > Betreff: Re: [PD] [vcf~] with resonance? > > Yes, thanks for the detailed response, Ed! > > I was hoping for some guidance for a bolt-on method for adding resonance > to vcf~, > but maybe it's not so easy? or the wrong approach? > > My error was thinking resonance was implemented with feedback. > > From this video, it looks like resonance is caused by a bump in the filter > shape at the cutoff frequency: > > https://youtu.be/XA_WnyA7D6k > > This looks like a shape that naturally occurs in analogue circuits. > Someone in the FB group suggested [svf~] from Cyclone. > It's really great, as it gives you HiP, LoP, BP, and Band Reject(!!). > > I would be in Filter Heaven if that had adjustable Q... > > PS: Can someone remind me of the filters where you can set parameters like > cutoff freq at *audio rate*? > > Thanks! > BH > > > > > On Wed, Apr 25, 2018, 11:09 AM Julian Brooks <jbee...@gmail.com[mailto: > jbee...@gmail.com]> wrote: > Well, regardless of the correct number of inversions, some informative and > well linked posts there - cheers for that Ed :) > > On 24 April 2018 at 20:44, Ed Kelly via Pd-list <pd-list@lists.iem.at > [mailto:pd-list@lists.iem.at]> wrote: > > The 4-pole model in the ENS-85 paper does not have inversion at the input, > but the Thomas Henry 2-pole design does. So I guess the 4-pole is more > similar to vcf~ > > go figure. > Signing off > Ed > > > _-_-_-_-_-_-_-^-_-_-_-_-_-_-_ > > For Lone Shark releases, Pure Data software and published Research, go to > http://sharktracks.co.uk[http://sharktracks.co.uk] > > > > > On Tuesday, 24 April 2018, 14:40:20 GMT+1, Ed Kelly via Pd-list < > pd-list@lists.iem.at[mailto:pd-list@lists.iem.at]> wrote: > > > > Ach! NO! inversion does not happen at the input! > I guess you can look at the topologies and discover for yourself. > > I'm having a bad week. > x > Ed > > > _-_-_-_-_-_-_-^-_-_-_-_-_-_-_ > > For Lone Shark releases, Pure Data software and published Research, go to > http://sharktracks.co.uk[http://sharktracks.co.uk] > > > > On Tuesday, 24 April 2018, 14:33:13 GMT+1, Ed Kelly < > morph_2...@yahoo.co.uk[mailto:morph_2...@yahoo.co.uk]> wrote: > > > > Correct me if I'm wrong (and I'm sure someone will) but going back to > analog electronics... > > If you examine the topology of a standard analog filter design, such as > the Thomas Henry VCF1 (http://www.birthofasynth.com/ > Thomas_Henry/pdf/VCF-1/Sheet_0002.pdf[http://www.birthofasynth.com/Thomas_ > Henry/pdf/VCF-1/Sheet_0002.pdf]) you will see that the signal path from > input to output goes through 5 inversion stages before being fed back into > the input to generate resonance. Therefore it is inverted. > > > Since most (resonant) filters consist of an even number of stages (and > therefore an even number of poles and/or zeroes) you should probably invert > the feedback. With an odd number you should probably not invert feedback. > My guess is that vcf~ implements an even-number (probably 4-pole) resonant > filter, a la Moog. You can also try mvcf~ from my library (ekext - > http://sharktracks.co.uk/puredata/ekext-0.1.8.tar.gz[ > http://sharktracks.co.uk/puredata/ekext-0.1.8.tar.gz]) which is another > attempt at emulating this topology, or there are lots of others I'm sure > you know about. > This might seem counter-intuitive, but the image below shows how this > works with regards to vcf~ - the output of vcf~ is NOT inverted, whereas > the output of an analog VCF should be. > Odd-number staged filters are very rare in the analog world, and most > (i.e. 18dB per octave) were created to implement the (mythical 3-pole > topology) filter of the Roland TB303. However, according to the schematics > of the TB303 it is a four-pole diode-ladder VCF using transistors as > diodes, with extra resonance artifacts revealed by Tim Stinchcombe on his > excellent website. Tim Stinchcombe - TB-303 Diode Ladder Filter model[ > http://www.timstinchcombe.co.uk/index.php?pge=diode2] > > > > Tim Stinchcombe - TB-303 Diode Ladder Filter model[http://www. > timstinchcombe.co.uk/index.php?pge=diode2] > > > > > > > Meanwhile, if you want to go deeper with regards to 4-pole filter > topologies (and lowpass/highpass configurations) it is worth checking out a > paper published in 1985 - http://electronotes.netfirms. > com/EN85VCF.PDF[http://electronotes.netfirms.com/EN85VCF.PDF] > > > > The easiest way to think about it, from this paper, is that you think > about each stage as an inversion, and the input itself is one of the > stages, so for a 4-pole filter there are 4+1 inversion stages. But in the > digital world I guess you'll have to test input and output at a relatively > low frequency to the cutoff to determine inversion principles for the > enhancement of resonance. > > I hope this helps. It gave me a break from mixing! > Ed_-_-_-_-_-_-_-^-_-_-_-_-_-_-_ > For Lone Shark releases, Pure Data software and published Research, go to > http://sharktracks.co.uk[http://sharktracks.co.uk] > > > > On Tuesday, 24 April 2018, 06:44:19 GMT+1, William Huston < > williamahus...@gmail.com[mailto:williamahus...@gmail.com]> wrote: > > > > What's the best or "correct" way to add resonance to a [vcf~]? > Should the feedback be delayed?Should the feedback be inverted?Should the > feedback be from the outlet I'm using? > Or should the feedback always come from the BP or HiPass side? > > Thanks! > BH > > > -- > William Huston: williamahus...@gmail.com[mailto:williamahus...@gmail.com] > Binghamton NY > > Public Service Mapping / Videography / Research > Blog[http://WilliamAHuston.blogspot.com] -- Facebook[http://facebook.com/ > billhuston] -- Twitter [http://twitter.com/WilliamAHuston] -- Youtube[ > https://www.youtube.com/channel/UCGijK1amWOLglT3YeTyEBNQ?sub_ > congfirmation=1] > Document collections: VirtualPipelines[http://TinyURL.com/VirtualPipelines] > -- BHDCSDimockArchive[http://bit.ly/BHDCSDimockArchive] > Please support my work: TinyURL.com/DonateToBillHuston[http:// > TinyURL.com/DonateToBillHuston] > _______________________________________________ > Pd-list@lists.iem.at[mailto:Pd-list@lists.iem.at] mailing list > UNSUBSCRIBE and account-management -> https://lists.puredata.info/ > listinfo/pd-list[https://lists.puredata.info/listinfo/pd-list] > _______________________________________________ > Pd-list@lists.iem.at[mailto:Pd-list@lists.iem.at] mailing list > UNSUBSCRIBE and account-management -> https://lists.puredata.info/ > listinfo/pd-list[https://lists.puredata.info/listinfo/pd-list] > _______________________________________________ > Pd-list@lists.iem.at[mailto:Pd-list@lists.iem.at] mailing list > UNSUBSCRIBE and account-management -> https://lists.puredata.info/ > listinfo/pd-list[https://lists.puredata.info/listinfo/pd-list] > _______________________________________________ Pd-list@lists.iem.at > mailing list UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list[https:// > lists.puredata.info/listinfo/pd-list] >
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