What kind of switch could I use for this?

[Connoisseur of Distortion]

why not use a SPDT on-off-on and something to strengthen, weaken, or ignore the path to ground? You could place a pot changing resistance to ground on one throw, place another pot on the other throw, and have it left alone unaffected when it's not connected to either. kind of a reeeeally simple LPF system...


                       ground
                           |
                      I---P
signal in -------O--------------| |--- signal out
                      I---P           (cap)
                           |
                        ground

to best improve performance, make sure i don't have this filter totally fubar, and you might put some series resistance from pot to ground, so you don't end up killing volume at one rotation of the knob... for cap value, just use your general formula to set the corner where you want it...

[spudulike]

Do you use this with other alpha pots? If so do you cut down the shaft?

The threaded shaft is almost the same dimension as a standard alpha pot (24 or 16mm), and the height is the same. The shaft is easy to cut as it is plastic.