Hello all,

An user reported a bug in the forum about some problematic behaviours of certain filters in pd-extended 0.43.4, particularly [hip~] and [bp~]. I found this bug to be also present in pd vanilla 0.46.5. Basically, these filters do not respond to frequencies higher than approximately 12 kHz, in contrast to [vcf~] which responds to any frequency. This can be very clearly observed in the case of [bp~] using a narrow band frequency sweep.

Here is a video showing the problem: http://youtu.be/A7mPhiHcmhc
Here is the topic in our forum where this discussion started: http://forum.pdpatchrepo.info/topic/8967/highpass-hip-not-working-as-expected/18
Here is that user's bug report concerning pd-extended: https://sourceforge.net/p/pure-data/bugs/1187/
Finally, here is the patch I am using to test this (I am using [spectrogram~] (which in its turn needs [metrum] and [multiplex~], all of which are included in this compacted file): https://www.dropbox.com/s/fcwciwe8klwh5xz/filter-test.zip?dl=0

NOTE: the user that reported the bug argues that pd vanilla 0.45.4 does not produce any problems, but I firmly believe this to be a mistake of him. I tested these filters in both 0.45.4 and 0.46.5 and both produce the same behaviour. I tried to contact him to ask for further tests (he was not using my patch above for his own tests), but so far I got no reply. Also, other users confirmed this bug to be present in both vanilla and extended.

Please let me know if I can be of any help with this.

Best,
Gilberto Agostinho

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