[sdiy] Boards for a parametric EQ?

[Andre Majorel]

On 2008-09-11 00:36 +0200, Andre Majorel wrote:

>   http://www.ethanwiner.com/spectrum.html
> 
> One problem with equalisers is sourcing the pots. I have a
> Rocktron here that uses dual gang reverse log (!) pots for the
> frequency control. Ethan specifies dual gang linear for his but I
> suspect that is not the right law. [...]

Just saw the Moog three band parametric EQ schematics :

  http://files.muziq.be/schematics/moog_pareq.jpg

The frequency controls are dual gang 100 k pots used as variable
resistors. The schematics do not say "log" or "anti-log" which
implies they're linear. And yet the angle-frequency relationship
is exponential :

  http://www.scale.gs/MoogParaEQ00.jpg

Is this possible ?

-- 
André Majorel <URL:http://www.teaser.fr/~amajorel/>
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