i have a morley bass switchless wah that has a filter rather like the second Q&D filter on tom's circuit snippets page:

http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html

it has 0.0068uF and 0.01uF caps in the feedback loop, and the regular morley  wah has 0.0068uF and 0.0022uF.  i put in a switch to go between these two combinations and was thinking about making it a rotary with a bunch of cap choices - does the ratio of these caps or anything like that affect the resonance or range?  can anyone recommend some values they like?  it seemed a bit odd to me that going from 0.01 to 0.0022 only took me up an octave or so.