Audio Shelving fliters

Hi all!

I'd like to implement 1st and 2nd order shelving filters - which are
generally called 6 db/oct and 12 db/oct filters.

I had a look at the 'Audio EQ Cookbook', but it doesn't say a word
about 1st order filters, and for 2nd order filters it's not clear to me
how the slope parameter S (S <= 1) relates to the filter slope
expressed in db/oct. Matlab simulations showed that RBJ's second order
filter could be a 12dB/oct when S is set to 1 - but in order to achieve
such a rolloff, the amount of boost or cut must be significant (about
30dB) so i keep doubting (Sorry RBJ your document is just great - by
the way thanks for making it available online - it's just that i don't
know how to use it).

I would greatly appreciate if someone could point a useful document -
common analog transfer functions ready for a bilinear transformation or
- even better! - digital transfer functions (yeah i'm a lazy bum ;) )

Thanks! Gus

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