Cheby Cheby Cheby.

[Martin Czech]

EN means Electronotes. Publisher B. Hutchins. This is a 6 folder large
publication for electronic music devices since 72 (I think) , it's
alive up to now. This was very frequently discussed in length in the
past, because of some difficulties.  There exist several EN summarys,
like engineer handbook etc, but they do not include a Tchebycheff filter
design. This is an original Hutchins circuit, so I can not disclose this
here (people already had trouble doing this).


Let me put it this way:

-you know a state variable filter with otas.
 There a a lot of examples on the net.
-you know that it is second order lowpass (here), with any Q
-you know that any all-pole lowpass can be constructed
 by using cascaded second order sections.
 
It is not so difficult to adjust the individual Fc and Q,
so that a 4th or 6th or 8th order Tscheby lowpass comes out.

Any larger modular system can do this.

I don't think that your ears will notice that your solution is only
near to the optimal filter. Just cascade a few , turn up Q for
some hunches, and then try to distribute the hunches.

A white noise input signal, a good soundcard and e.g. cool-edit will
be helpfull to set up the transfer function.

Anyway, three individual PARALLEL resonant filters (voltage controled)
will be more usefull vor vowel sounds.

m.c.