[PD] parametric equalizer

Raphaël Ilias phae.ilias at gmail.com
Fri Apr 20 17:15:42 CEST 2018


Thanks Alex and Dan,
I am very busy now but I'll look into your solutions ASAP.

I am aware of ggee objects for biquad~ coefficient calculations.
Tough I understand the idea to "split the spectra" of a signal with
low-pass, band-pass and high-pass filters...  what is still unclear to me
is : since the outputs of the filters are then mixed together, how to make
sure that overlap correctly so that if the 3 (low, band and high) filters
have 0db gain ([*~1]) the sum of the 3 together will be similar to the
input (flat response), like it does when your mixer's EQ knobs are all
centered...
and what does it really mean when you turn it counter-clockwise, for
example "MID knob" to -6 dB ?
I suppose it isn't a rejection/notch filter ? So it's just a bandpass
filter with amplitude 0.5 / -6 dB and then mixed with the outputs of the
lowpass and highpass filters ?
Probably there is no perfect design, but I wonder what details I should be
aware of.

But I will study the abstractions/objects you mentioned.

++

2018-04-19 20:11 GMT+02:00 Dan Wilcox <danomatika at gmail.com>:

> Check out [e_3bandeq] in rc-patches: https://github.
> com/danomatika/rc-patches
>
> On Apr 19, 2018, at 11:55 AM, pd-list-request at lists.iem.at wrote:
>
> From: Raphaël Ilias <phae.ilias at gmail.com>
> To: pd-list <pd-list at lists.iem.at>
> Subject: [PD] parametric equalizer
> Message-ID:
> <CADYAdN8jH+dSyr54KPbM5P94+ZOBHKfdgYyOkuW5uS4w3O6gGg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hello dear pd lovers,
>
> I wonder if someone as implemented a parametric equalizer similar to the
> ones you find on mixer : like three band LOW MID HIGH, with -/+ X dB so
> that when everything is +0 dB, the output is flat and similar to input.
> And eventually with Q/curve/spectral transistion parameters ?
>
> I know this is a very large question and that there might be a lot of
> different implementations, but I wondered if there are "standard"
> solutions.
> Vanilla preferred or stable libraries...
>
> Thanks !
>
> --
> Raphaël Ilias
>
>
> --------
> Dan Wilcox
> @danomatika <http://twitter.com/danomatika>
> danomatika.com
> robotcowboy.com
>
>
>
>


-- 
Raphaël Ilias
  ___________________________________
*     phae.fr <http://phae.fr>*
     17 places des Halles - Ingrandes
     49123 Ingrandes Le Fresne s/ Loire
     phae.ilias at gmail.com / +33 (0) 6 04 45 79 78
  ___________
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