[sdiy] Fixed filter bank questions
David G Dixon
dixon at mail.ubc.ca
Thu May 9 01:16:40 CEST 2019
Concerning changing the centre frequency from 1000 Hz to 640 Hz...
I've done a bit of analysis, and my assessment is that it really doesn't
If you use 1000 Hz as the centre, then you have 6 BP filters below that
going down to 125 Hz, with the LP at 88 Hz, and 5 BP filter above that going
up to 5657 Hz, with the HP at 8000 Hz.
If you use 640 Hz as the centre, then you have 5 BP filters below that going
down to 113 Hz, with the LP at 80 Hz, and 6 BP filters above that going to
5120 Hz, with the HP at 7241 Hz.
The result is that all of the BP filters have shifted a little less than two
semitones downward. Nobody is going to notice this difference. I'm going
to stick with the more Moogy frequencies out of a sense of tradition. Plus,
I like putting the rounder numbers on the front panel.
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