Hello ! Thanks a lot everyone. Thanks for the book info Vadim. I was not notified that this thread was going on, so I forgot it. I managed to make something work, but sonically speaking, it was far from a moog filter :-)
The appearance/disappearnce of the resonance effect was pretty brutal, and with a kind of veil on the higher frequencies. I should have taken a screen shot of the "circuit" (the interconnected modules, mix, feedback, and may be gain). But I think I was too ashamed of my first attempt :) I had to do something else (much much easier = a 4*32 step sequencer with many modulators and triggers) that controls eurorack, using a scope dsp card, and a exprt sleepers converters, no sound magic involved . :-) I've also been educated to dsp cards with development kits, for pretty cheap prices (compared to when I last checked 10 years ago). but right now i will try native tools to try to translate what i've build recently. To be continued .... Mehdi (for examples of what i've been "building" or putting together) https://spacef-devices.com Le lun. 23 juil. 2018 à 11:42, Vadim Zavalishin < vadim.zavalis...@native-instruments.de> a écrit : > On 20-Jul-18 18:13, Mehdi Touzani wrote: > > So... how do you do a resonance in a lowpass circuit? :-) not the > > math, not the code, just the architecture. > > There are many different ways to create resonance in a lowpass circuit > (esp. if the order is larger than 2). The higher is the order of the > filter, the more different answers there are. > > Making a feedback loop around a lowpass chain is one way, but AFAIK it > works perfectly (or close to that) only for the 4th order filter (the so > called Moog ladder). I'm not aware of any standard generic structure (or > even a transfer function to begin with) which could be referred to as a > generic Nth order resonating filter. Recently I tried to propose one way > of generalizing the 2nd order resonance to an arbitrary order by what I > called "Butterworth filters of the 2nd kind", but this involves just the > transfer function, whereas you still have lots of freedom in the > implementation structure. You could look into the latest revision of my > book for more details (where I also explain the problems with the > lowpass feedback). > > Regards, > Vadim > > > -- > Vadim Zavalishin > Reaktor Application Architect > Native Instruments GmbH > +49-30-611035-0 > > www.native-instruments.com > > _______________________________________________ > dupswapdrop: music-dsp mailing list > music-dsp@music.columbia.edu > https://lists.columbia.edu/mailman/listinfo/music-dsp > >
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