[LAU] Mackie Onyx like channel strips?

[Fons Adriaensen]

On Sun, Nov 19, 2017 at 02:15:04PM +0100, David Kastrup wrote:
 
> Out = In*((3.47kOhm+1/(0.0033uF s)+10kOhm-b*10kOhm)|510kOhm)
>         /((3.47kOhm+1/(0.0033uF s)+10kOhm+b*10kOhm)|510kOhm)
> 
> Where x|y is (xy)/(x+y) and s is the transform domain variable (for a
> Fourier transform, it would correspond to 2 pi j f with j being sqrt(-1)
> and f being the frequency).

This looks like the 1640 HF shelf.
 
> If we convert this to a general IIR form, we'll likely get more
> polynomial coefficients than we are comfortable choosing all on our own.

What do you mean ? This is just a first order filter of the form

F(s) =  (1 + as) / (1 + bs)

Unity gain for LF, a/b for HF. 

-- 
FA

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