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Subject: Re: [motm] FFB slopes

From: jhaible@...
Date: 2002-12-20

> The steepness of the bandpass filter slopes on the FFB came up in a
> conversation I was having. But the answer was not known. So the question is
> what is the slope on each side of the bandpass filters in the FFB? 6dB/oct,
> 12dB/oct or other? Thanks for any info.

Simple answer: "other".

Slightly more elaborate answer: These are high Q, stagger tuned BPFs,
where the "slope" as we know it from LPFs and HPFs would be very
misleading, because we're working in the resonant peak region, not
in the slope region. Of course you can define something like a "slope"
in the resonant region, too, only that it's not approximately constant
there.

Possibly more helpful answer: It's modelled after the Moog Fixed
Filter Bank, and I think the response courves for this are published
at the Moog archives site. (I think Paul even posted a link to
this a few weeks ago.)

JH.

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