🚀 go-pugleaf

      Steve, am I wrong to use the FFT filter as a HPF? Are we killing the rest
      of the spectrum phase-wise?




It's all a bit moot. I looked out (and modified slightly) a post I made about this six years ago about phase errors and filters on the old Synt forum archive:

      FIR filters can be constructed to be linear phase or not - usually they
      are, but it's not obligatory. IIR filters (ie using feedback techniques)
      can be made to ring, and there are also techniques for reducing the amount
      of non-linearity in them.





      Calling them phase 'errors' is a little misleading. All filters will have
      a phase shift, or delay associated with them - they wouldn't work otherwise.
      The critical part is the linearity of the shift, and that is where FIR
      filters are more likely to give a good 'musical' result.





      AFAIK, the CEP parametric EQ filters are definitely IIR - I can make them
      ring.




This would seem to indicate that using the Scientific Filters to remove rumble would be a perfectly fine idea - but ultimately, if it sounds okay - then it is! And quite frankly, we are only talking about a very low frequency effect, and even many degrees of shift are going to be subjectively less noticeable than they would be at, say, a speaker crossover frequency, and that's why I think it's a moot point.