Re: BiQuad frequency response for visualisation

On Jun 30, 3:16 pm, Vladimir Vassilevsky <antispam_bo...@xxxxxxxxxxx>
wrote:
Greg Berchin wrote:
On Jun 30, 1:59 pm, robert bristow-johnson <r...@xxxxxxxxxxxxxxxxxxxx>
wrote:

now, if you retain the same EE definition of Q for the peaking EQ (and
the old analog EQs do that, e.g. pultec), then you find that if you
leave Q constant, a cut of N dB is not the inverse filter of a boost
of N dB.  the cut is a lot skinnier looking than the boost.

In the last audio EQ that I designed, the customers demanded boost/cut
symmetry in EQ filters, so I (re)defined Q accordingly.

Exactly. The similar adjustment has to be applied for the shelving
filters for tone control.

i guess i don't know what you mean, Vlad. do you mean to adjust the
value of Q (when the shelf gain changes) so as to keep the steepest
possible monotonic slope of the shelf?

otherwise, what Q adjustment are you guys referring to?

r b-j
.

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