[sdiy] pots with centre detent?

[Florian Anwander]

Basically it is always the same

Dave Kendall wrote:
> Got a rackmount parametric EQ that has exactly that, but looking inside,
> it uses a dual log 10K somehow to do the job.
> I haven't got a schematic for it, but would be intrigued to find out how
> it might have been done - I guess it's likely to be another old
> trick.... ;-)
usually the dual log are not for the amount, but for center fq. Normally 
the amount is achieved with a linear potentiometer, which pans between 
inverted and noninverted signal in some way.

Two examples:
http://fa.utfs.org/diy/studiomaster_16_4/channel.tif
The typical semiparametric bandpass in the "presence" section.

A bit more interesting:
http://fa.utfs.org/diy/moogparametric/moog_parametric_eq.jpg