[sdiy] 'State-Variable' vs. 'Multi-Mode' filters - differences?

Neil Johnson neil.johnson97 at ntlworld.com
Thu Jul 5 01:01:00 CEST 2012


Hi Don,

> The Linkwitz-Riley is just two cascaded filters with some interesting mathematical results.

Yes, the standard approach is two 2nd order Butterworth's in series.
But Rane came up with a solution based on a 4th order SVF:

http://www.rane.com/pdf/linriley.pdf

That _is_ a fourth-order state variable filter.

[lots of other stuff skipped over...]

> Hmm, when you have analog switches flipping around the topology all bets are off, right?  I mean, I could have analog switch changing a filter into a ring modulator.

You could, but then it wouldn't be called a 'multimode filter' would
it?  It'd be called a 'multimode filter and ring modulator' :)

Cheers,
Neil
-- 
Modules and more: http://www.cesyg.com
Homepage: http://www.njohnson.co.uk



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