Frank Barknecht wrote:
that is true, but it looks like no one has made a (usual lp,hp,etc.) filter with these objects until now.
Except Miller. [1]
you are right, there are some "usual filters" made with pole/zero objects, the shelving and peaking ones, a nonresonant lp and a bp, iirr. and the examples in millers book have been very helpfull with my own attemps to make a resonant lowpass. but the "standard" filters (resonant 2,4 pole lp,hp,bp,notch,...) for sound synthesis do not exist (yet) in "vanilla-pd".
Though I agree that some more of these would be handy. I tried to make a biquad~ clone with the elementary filters, but failed so far. I assume from [2] that the transfer function of two rzero~ and two rpole~ in series should be the same as a biquad~, however I don't know how to convert the ff1, ff2, ff3, fb1 and fb2 coefficients of biquad~ into the coefficients to use at the second inlets of the elemetary filters. Can anyone help?
i had the same problem, and did not find a solution. (it might be quite complicated anyway), so i tried to build a filter by "directly" placing the pole and zero. it sounds not bad, but i still have a problem with scaling the output correctly. if i use this filter in a synth i have to adjust the volume quite often.
bis denn! martin