Hey,
does anyone know if there is something like an audiosignal-controlled allpass-filter?!?
I know of these [(r)pole~] and [(r)zero~] objects, but I have to admit, I have no clue of how to get the frequency- and filter-(allpass-)characteristics "into" it.
Does somene maybe have a link or two?!?

I found/used the [ap1/2~] that uses the [filter~]-object, but those are only data-controlled... and "sampling" the audio-signal of an ADSR for example with a [bang~]/[metro] and a [snapshot~] seems to be the only but jet CPU-expensive way...
The ony audio-controlled filters I know of are [vcf~] and [svf~], at least no allpass...
Are there more???

Thx & bye
Flipp

I use [svf~] as a resonant allpass filter by summing lopass, bandpass and hipass output. Each output needs it's own level and delay though, see attached patch. And even then it is not exactly allpass, but an approximation with problems in the ultra high frequency range.

But maybe you need a maximum-phase allpass filter? [comb~] does that, and it is signal-controlled.

Katja

http://www.pdpatchrepo.info/hurleur/resonant-allpass.zip

Thanks Katja,
...but I think it doesn't work in my case..
Btw. why is this second "1" in [delay~ 1 1] there?! It seems to change something but what, and how did you find this?!
Bye
Flipp

from helpbrowser/Pure data/3.audio.examples/H.14.all.pass.pd

[rzero_rev~]
|
[rpole~]

input signal or float -0.99....0.99

mvh

@Flipp said:

why is this second "1" in [delay~ 1 1] there?!

The first argument is max delay in samples, and the second argument is the actual delay. If you don't specify the second argument the actual delay must be specified with a message in the right inlet, otherwise it will default to zero. That is what I remember from Max Msp and [delay~] is a cyclone object. In Pd it seems to work the same. So the one-sample delay would be a zero-sample delay otherwise!

Katja

ah yeah that makes sense.. Which one is better, CPU-wise, the [z~ -1] or the [delay~ 1 1] ?

@ pulsed or anyone: Do you perhaps know the "conversion-function" from frequency to the filter-coefficient(s) ?!
And is there such a filter for an 2.order allpass with q-factor!? I rather need that one!!
There must be a way to solve this. If it won't work with [rpole~],... it at least should work with [cpole~],... Does someone know a webpage with some informations or a short introduction?
Thanks anyways
Flipp

I posted abstractions for second-order filters here:

http://puredata.hurleur.com/sujet-5342-signal-controlled-filters

I got most of the math for it from here:

http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt

Great, thanks.
..but I'm missing the [complex_div.mmb]-like objects...

Oh, shit. I forgot to include those. I think I posted them on here before, but I'll add them to the post. Thanks for pointing it out.