[music-dsp] Ripple specification for Chebyshev Type I Low Shelf?

Martin Eisenberg martin.eisenberg at udo.edu
Tue Jun 9 12:17:27 EDT 2009


Vinnie wrote:

> When ripple exceeds the gain I just want to set the ripple
> equal to the gain.

When gain and ripple are too similar the response can't really be
said to be "close" to the gain anymore. That's why Orfanidis
talks about reducing ripple (bringing G and Gb closer together)
if G approaches G0 in section 7.

> what do I do when both the gain and the ripple are 0 dB
> (i.e. the identity filter)?

Generate no roots at all. This should result in setting
coefficients that produce the identity exactly.


Martin



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