Maybe Alexandre Torres Porres is right, since the numbers at which the filters stop responding seem to be "designer numbers".
Indeed they are suspicious numbers, so this seems to be true.
But there are still some things left to be explained. When I did a test using 4 high pass filters in a serial manner, things didn't go as expected
What exactly was the problem?
Anyway, we can accept their limitations
Yes, but I find this a bit annoying since [hip~], [lop~] and [bd~] are the first filters a beginner in Pd learns to use (virtually all tutorials use them). It's like having better tools that are also a bit hidden, or even worse, nobody knows that they are better. In the lower part of the spectrum, [vcf~] and [bd~] are virtually indistinguishable.
And one more thing: someone in the list also recommended [iemlib/hp1~], which is a much better high pass filter that works with any frequency. If I would have any saying in this all, I would just replace [hip~] for it and call it "problem solved"...