Hi!
I'm trying to use [pp.fft-split~] abstraction from audiolab lib as a phase-accurate anti-aliasing / downsampling-filter:
But the cutoff-frequency is changing with the upsampling factor. And it doesn't sound clean.

Do you know why?

here is the patch:
up_fft_filt_1a.pd

@solipp

found it:
after a change in samplerate, the frequency needs to recalculate
by adding this: