Scroll down for new and improved or click https://forum.pdpatchrepo.info/topic/13621/20-mode-pole-mixing-and-morphing-filter-updated/10

Quick experiment that @jameslo got me thinking about, turned out well. You get 20 modes and you can morph between them. Probably has room for improvement, I do not do much audio work in pd. Enjoy.
polemix.zip

@tungee - Be mindful of the inversion pattern after the end of each filter stage. Oid and I put inverters after each. IIRC solipp put none, and thus stage 2 and 4 need inversion ( [*~ -1] ) before applying pole-mix coefficients.

And don't forget to share your filter when it's working (new thread maybe?)

@tungee If memory serves, Bernie Hutchins (originator of the filter) covers everything you need in his original article on the topic, http://electronotes.netfirms.com/EN85VCF.pdf.

@oid said:

http://electronotes.netfirms.com/EN85VCF.pdf.

Awesome find! BUT- the problem, as you have pointed out in this thread before, is that analog circuitry math does not translate well to digital, especially in the case of filters. https://archive.org/details/the-art-of-va-filter-design-rev.-2.1.2 was an eye-opener for me in terms of the limitations of our standard digital 1 pole algorithm.

The TPT filter suggested (which solipp employs in his ladder filter) solves a LOT of the problems we have been struggling with. However, there is no way to implement it cpu-cheap unless someone sits down and makes an external [tpt_lop~] object (with signal rate cutoff) for PD. I wonder if it could be hacked with [rpole~]...?

Hey OID i have read the article a year ago... You had posted this in the Karlsen thread. Should read it again a very nice article.

Bythe way in one hour the battle of the Filters begin
stay tuned!

@bocanegra Yeah, I know little of digital techniques, this is one of the few times I successfully moved something from the analog world to the digital, but the calculating of the ratios should be covered and will work.

@tungee I did not see that I posted it there, I had completely forgotten about that thread until it was posted in the [bob~] thread. But you can get all the mix ratio from my filter, the version in the first post is the simplest, no morph and much simpler, you should have no issues figuring that one out, all those message boxes are just the mix ratios for the 20 modes. I will probably have the resonance morph fixed by weeks end, just have not had the time to finish it up. As I said earlier, I do not do much audio work in pd, I just posted this so people would have it and the technique, so low priority for me.

The Battle of the Pure Data Filters has begun:

@tungee Oiderheim wins on name alone. That made me chuckle.

OId i wanted it name Matrixoid first

Just wanted to say this thread is tight and made me smile