On 24 June 2014 06:37, Urs Heckmann <u...@u-he.com> wrote: > > On 23.06.2014, at 19:18, robert bristow-johnson <r...@audioimagination.com> > wrote: > >> it *is* precisely equivalent to the example you were describing with one >> more iteration than you were saying was necessary. > > Now I'm really angry I wasted so much time. An example is just that, an > example. I deliberately kept it very simple to show the ? principle. In > Germany we have a saying that roughly translates to "pass someone a finger > and he'll grab the whole hand". That's what you did. Good luck storing a one > pole filter in a 3 dimensional look up table. You think we haven't thought of > that in five years of researching that field? Even if you succeed for a > measly non-linear one pole filter, try look up tables for a two pole filter. > Or one for a six pole filter, which is the minimum if you want to sound close > to "that" transistor ladder filter and which makes, uhm, something like 18 > dimensions? THAT is a scary concept.
Please keep in mind Urs that RBJ is being a grumpy old engineer that is resistant to change just for the sake of it. He has a proven track record in taking anything you say and do his grumpy best to misinterpret what you have written just to be difficult, since stalling means he doesn't have to learn anything new. > My one most important question was never answered though: What advantage does > a DF-anything filter have over a direct implementation when modeling a > circuit in software? My vague feeling: There is no answer. > > I had to get this off my chest. I'm off for a drink. > > - Urs ATTENTION RBJ: Before you reply to this I think what Urs left out is HE IS NOT TALKING ABOUT THE LTI CASE. In the LTI case (ie static filter that never changes from now to the end of time) and with infinite precision then there are loads of equivalent methods that will produce identical results eg: is you use H(s) and the bilinear transform with an implementation structure of DF1/2/transposed/digital wave/lattice/... or you use direct trapezoidal integration. -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
