@ddw_music you were right, problem solved :

@ddw_music very nice! With your downward edge detection I can now divide a phasor~ by an arbitrary number. There's a thing I cannot wrap my head around though: how to reset the counter to zero every divided downward edge. So it can safely be run indefinitely.

I don't understand why feeding the rpole~ argument with ((1-(divided downward edge detection)) delayed by one sample) only resets it once in a while and not every cycle.

@RT-Chris you should have a look at how it's done in Automatonism
@jameslo absolutely brilliant!

so I totally gave up on solving my maths problems in pd. I used FAUST instead and run my tonestack~.dsp in [faustgen~].
you can access the 3 parameters with [low/med/top $1( from 0 to 1.
first time with FAUST, looks awesome.

Wew lads! What a complicated topic. Finding real roots for the denominator, finding either 3 real or 1 real and 2 conjugated complex roots for the numerator... The current filter is 100% highly unstable, I hope I'll get it working eventually.

so far my best guess would be https://en.wikipedia.org/wiki/Cubic_equation#Trigonometric_solution_for_three_real_roots

Hi,
I'd like to implement in pure data the tone stack model I found in the DAFX book. It's a linear third order transfer function. In the book they use mathlab which seems to have a routine to solve it so the code they give is of no use to me.
In pd, should I find the roots of both third order polynomials and use poles and zeros objects like in Maelstorm tutorial? Does his method transpose? Should I use fexpr~ instead? Is there another method?

@manuels said:

Subtracting the result of a halfwave readout of [cos~] from the regular full wave readout doesn't give zero output for the second half of the cycle.

This reminds me of https://forum.pdpatchrepo.info/topic/13709/bug-osc-cos-circle-asymmetry-drifting-out-of-phase/1

@raynovich in the worst case you'll be learning things, you're in good hands with @whale-av

@bocanegra said:

See also this video on reverb design which goes through the history of reverb

Rarely did I spend an hour or so on YT so well. Thanks a lot. Do you have other interesting lectures like that to share?