[apb2390]

Originally Posted by otherguy

That's because they are logarithmic
http://en.wikipedia.org/wiki/Potentiometer#Resistance.E2.80.93position_relation ship:_.22taper.22

Most commercially available 'log' pots, like the ones you get at radioshack and Fry's, have more of a two-stage adjustment, as it's cheaper to make two parallel sections of resistive material than to actually taper the resistive material in a logarithmic fashion.

More info here: http://sound.westhost.com/pots.htm#taper