Re: BiQuad frequency response for visualisation



robert bristow-johnson wrote:

On Jun 30, 3:16 pm, Vladimir Vassilevsky <antispam_bo...@xxxxxxxxxxx>
wrote:

Greg Berchin wrote:

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?

As noted by Greg, they want the boost and cut responses to be symmetrical. I.e. the cut response should look like a mirror image or the boost response. This applies to the EQ sections as well as to the tone control sections. With EQ sections, we have to adjust Q by gain, and with the shelving sections, we have to adjust the corner frequencies.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
.

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