Iam using puredata vanilla to develope a mobile app with libpd. I dont use any externals from PD Extended,
Playing with the [lop~] [bp~] and [hip~] filter I recognized some strange behaviour. The lowpass is working well. But the highpass filter does not work for me. Filtering a [pink~] signal with [hip~ 20000] does not filter the signal like i would expect. Look at the following images illustrating the problem. Iam using a patch with 4 serial highpass filter with the same input frequency. Until 6000Hz everything is fine, but then things do not work as anticipated. Using a [noise~] instead of [pink~] makes the filter even more impractical.
Maybe Im totally wrong and thats the normal way it should work?
The Test Patch: hip-test.pd
Thanks in advance!
Edit: I have been playing around with the [bp~] filter and noticed some strange behaviour, too. Until 13kHz everything is working as expected. However cut-off frequencies above this value are not working anymore and the cut-off will still stay at 13kHz. The [vcf~] is working fine and it does what it is meant to do.