Dear All,

I'd like to replicate the equalizer stage of some guitar pedals/amplifiers.

I've attached the eq curves of the boss HM2 pedal and this is a snippet of what i've come up using eqfil (the frequency values are roughly taken from the image attached):

Is there a method to better approximate these curves or in general to recreate eq curves using filters?

Thank you in advance

Stefano

Dear Stefano,
Jul 30 2019, 00000008a49663bc-dmarc-request@LISTSERV.HEANET.IE has written:
...
> Is there a method to better approximate these curves or in general to recreate eq curves using filters?
...
I have no definitive answer, but I have been interested in that field
myself, sparked by "matching EQs".

Filtering your origina signal, from the Boss pedal, and then volume
analysing them might be a start. Csound has the rms opcode. I thought if
you take a really low lowpassfilter (ihp) and run audio through ti
analyse relative volumes, you could later apply these to eqfil bands.

Another basic idea I had was to use FFT analysis and again look at
certain frequency bands, looking for mean magnitude/amp values.
Depending on the exact mirroring of frequency bands you want, you could
analyse each FFT bin and calculate a kind of IR for that. I.e. render a
very short audiofile and use that with a convolution opcode. Though I
have a feeling that there would be some caveats. For this to really work
you should put white noise through your pedal.

Both methods - any kind of EQ'ing for that matter - won't model or mimic
distortion effects or any other nonlinear behaviour of your pedal.

If you yourself create a setup - or find an existing setup - in Csound
that works, I'd be very interested! I'd be willing to discuss this
further, only mind that my knowledge is sketchy and not very
scientifically founded, no real DSP experience.

Best wishes and good luck,

Jeanette

-- 
  * Website: http://juliencoder.de - for summer is a state of sound
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But now I'm Stronger <3
(Britney Spears)

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Thank you Jeanette,
the problem is that i don't have the actual pedal, only these type of eq graphs and I'd like to know if there is a good method/approach to translate these to butlp, eqfil, lowpass, etc

For the actual distortion I'm playing with excel to calculate transfer functions or polimomials, maybe I'll use ltspice to have transfer functions of circuits.

bye

> Il 30 luglio 2019 alle 14.58 "Jeanette C."  ha scritto:
> 
> 
> Dear Stefano,
> Jul 30 2019, 00000008a49663bc-dmarc-request@LISTSERV.HEANET.IE has written:
> ...
> > Is there a method to better approximate these curves or in general to recreate eq curves using filters?
> ...
> I have no definitive answer, but I have been interested in that field
> myself, sparked by "matching EQs".
> 
> Filtering your origina signal, from the Boss pedal, and then volume
> analysing them might be a start. Csound has the rms opcode. I thought if
> you take a really low lowpassfilter (ihp) and run audio through ti
> analyse relative volumes, you could later apply these to eqfil bands.
> 
> Another basic idea I had was to use FFT analysis and again look at
> certain frequency bands, looking for mean magnitude/amp values.
> Depending on the exact mirroring of frequency bands you want, you could
> analyse each FFT bin and calculate a kind of IR for that. I.e. render a
> very short audiofile and use that with a convolution opcode. Though I
> have a feeling that there would be some caveats. For this to really work
> you should put white noise through your pedal.
> 
> Both methods - any kind of EQ'ing for that matter - won't model or mimic
> distortion effects or any other nonlinear behaviour of your pedal.
> 
> If you yourself create a setup - or find an existing setup - in Csound
> that works, I'd be very interested! I'd be willing to discuss this
> further, only mind that my knowledge is sketchy and not very
> scientifically founded, no real DSP experience.
> 
> Best wishes and good luck,
> 
> Jeanette
> 
> -- 
>   * Website: http://juliencoder.de - for summer is a state of sound
>   * SoundCloud: https://soundcloud.com/jeanette_c
>   * Youtube: https://www.youtube.com/channel/UCMS4rfGrTwz8W7jhC1Jnv7g
>   * GitHub: https://github.com/jeanette-c
>   * Twitter: https://twitter.com/jeanette_c_s
> 
> You might think that I won't make it on my own,
> But now I'm Stronger <3
> (Britney Spears)
> 
> Csound mailing list
> Csound@listserv.heanet.ie
> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
> Send bugs reports to
>         https://github.com/csound/csound/issues
> Discussions of bugs and features can be posted here

Csound mailing list
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https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
Send bugs reports to
        https://github.com/csound/csound/issues
Discussions of bugs and features can be posted here