[sdiy] Boards for a parametric EQ?

[ChristianH]

On Fri, 12 Sep 2008 10:54:26 +0200 Andre Majorel <aym-htnys at teaser.fr> wrote:

> 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 ?

Well, in the Mini schematics, all the mixer level pots don't have a
specific log marking either. May be they implied log where it's kind of
obvious? I mean, audio level pots are usually the prime example for
using log pots.

Christian