[PD] Resonant filter using cpole~ czero~

Charles Henry czhenry at gmail.com
Thu Feb 2 15:36:41 CET 2012


On 2/2/12, Patrice Colet <colet.patrice at free.fr> wrote:
>
>> De: "Ed Kelly" <morph_2016 at yahoo.co.uk>
>
>>
>> Hi all,
>>
>> Here is my first attempt at making a resonant lowpass filter using
>> cpole~ and czero~ objects. It's the first version I've made which
>> actually sounds halfway towards what I want to achieve, which is a
>> decent diode-ladder or transistor-ladder filter emulation. I want to
>> make this using only vanilla objects, particularly rpole~, cpole~
>> etc. so that they can be ultra-portable and signal-controlled. Also,
>> http://www.timstinchcombe.co.uk/index.php?pge=poles#diode
>>
>>
>> Does anyone else have any ideas, or patches we can share?
>>
>>
>> Ed
>>
>> Gemnotes-0.1alpha: Live music notation for Pure Data
>> http://sharktracks.co.uk/
>
>
> hello,
>
>  using biquad~ gives very nice results for resonant filtering, ggee audio
> filters show how it sounds. It should be possible to use vanilla's audio
> math objects only for the biquad mathematical functions instead of an
> external.


Hi Ed, Patrice

This patch ds~ (damped sines) uses the biquad.  It works as a resonant
filter--I like to feed it impulses.  The arguments to the patch are
frequency and the number of ms to decay 10 dB ( I think).  Copied
below.
Chuck

ds~.pd
---------
#N canvas 0 0 337 561 10;
#X obj 12 384 biquad~;
#X obj 57 351 pack f f f f f;
#X obj 145 188 exp;
#X obj 156 98 * 44.1;
#X text 209 96 ms to samples;
#X obj 156 119 t b f;
#X obj 145 154 / 44100;
#X msg 91 118 -2.30259;
#X obj 145 219 t f f;
#X obj 17 148 * 6.28319;
#X obj 63 208 sin;
#X obj 26 210 cos;
#X obj 60 257 * 2;
#X obj 45 290 * 1;
#X obj 92 256 t f f;
#X obj 92 279 * 1;
#X obj 82 313 * -1;
#X msg 132 302 0;
#X obj 166 303 * 1;
#X msg 199 302 0;
#X obj 32 119 / 44100;
#X obj 34 180 t f f;
#X text 176 189 a;
#X text 13 229 cos and sin of b;
#X obj 32 78 unpack f f;
#X obj 56 460 outlet~;
#X obj 11 31 inlet~;
#X obj 73 32 inlet;
#X obj 158 8 loadbang;
#X obj 158 53 \$1;
#X obj 188 53 \$2;
#X obj 158 30 t b b;
#X obj 124 75 pack 100 10;
#X connect 0 0 25 0;
#X connect 1 0 0 0;
#X connect 2 0 8 0;
#X connect 3 0 5 0;
#X connect 5 0 7 0;
#X connect 5 1 6 1;
#X connect 6 0 2 0;
#X connect 7 0 6 0;
#X connect 8 0 12 0;
#X connect 8 1 14 0;
#X connect 8 1 17 0;
#X connect 8 1 19 0;
#X connect 8 1 18 1;
#X connect 9 0 21 0;
#X connect 10 0 18 0;
#X connect 11 0 13 0;
#X connect 12 0 13 1;
#X connect 13 0 1 0;
#X connect 14 0 15 0;
#X connect 14 1 15 1;
#X connect 15 0 16 0;
#X connect 16 0 1 1;
#X connect 17 0 1 2;
#X connect 18 0 1 3;
#X connect 19 0 1 4;
#X connect 20 0 9 0;
#X connect 21 0 11 0;
#X connect 21 1 10 0;
#X connect 24 0 20 0;
#X connect 24 1 3 0;
#X connect 26 0 0 0;
#X connect 27 0 24 0;
#X connect 28 0 31 0;
#X connect 29 0 32 0;
#X connect 30 0 32 1;
#X connect 31 0 29 0;
#X connect 31 1 30 0;
#X connect 32 0 24 0;



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