Hi ! I don't have the skills (and honestly the time for now) to change source code and compile it. However, I made a test patch that demonstrates the behaviour of [notch] when pd dsp is computed at 48000Hz, and the trick I use to correct it.
Cheers, Raphaël
#N canvas -841 -51 820 513 10; #X obj 106 282 biquad~; #X obj 146 245 ggee/notch 1000 10; #X msg 146 213 1000; #X obj 40 233 osc~ 1000; #X obj 106 371 nbx 10 14 -1e+037 1e+037 0 0 empty empty empty 0 -8 0 10 -262144 -1 -1 96.3188 256; #X msg 40 183 1000; #X obj 533 298 biquad~; #X obj 573 261 ggee/notch 1000 10; #X msg 573 120 1000; #X obj 467 259 osc~ 1000; #X obj 533 387 nbx 10 14 -1e+037 1e+037 0 0 empty empty empty 0 -8 0 10 -262144 -1 -1 9.76611 256; #X msg 467 171 1000; #X obj 573 165 t f b; #X obj 600 189 samplerate~; #X obj 600 209 / 44100; #X obj 573 229 /; #X obj 533 344 env~ 8192; #X obj 106 328 env~ 8192; #X text 16 53 if pd's samplerate is configured at 48000 \, the filter's center frequency isn't actually at the frequency sent to [notch] inlet. ; #X text 16 93 below you can see that \, when working at 48000 samples/sec \, the real center frequency is measured around 1088.44 Hz (where enveloppe is around -90db).; #X text 462 67 so frequency parameter for [notch] should be shifted accordingly to current samplerate \, which we get through [samplerate~] ; #X msg 80 183 1088.44; #X text 166 264 notch filter \, a 1/10th of octave bandwidth; #X connect 0 0 17 0; #X connect 1 0 0 0; #X connect 2 0 1 0; #X connect 3 0 0 0; #X connect 5 0 3 0; #X connect 6 0 16 0; #X connect 7 0 6 0; #X connect 8 0 12 0; #X connect 9 0 6 0; #X connect 11 0 9 0; #X connect 12 0 15 0; #X connect 12 1 13 0; #X connect 13 0 14 0; #X connect 14 0 15 1; #X connect 15 0 7 0; #X connect 16 0 10 0; #X connect 17 0 4 0; #X connect 21 0 3 0;
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