Originally Posted by wild4oldcars
Pot values are another thing to keep mind of. 25k or 50k (darker or brighter, respectively) with active pups, 250k or 500k (darker or brighter, respectively) with passives. Most preamps I've encountered use linear taper pots (B), but I prefer logarithmic taper (A). Simply a matter of opinion on those, though.
Preamps use linear taper pots with center detents for EQ. And you wouldn't want to mess with values. Changing the values and tapers will compromise the functionality of the EQ.
For volume pots, however, you must always use 250k or 500k pots, if you intend to do active/passive switching. The use of a 25k or 50k pot would only be suitable for a master volume, placed after a preamp. And in which case, it must be bypassed for passive operation, or else the pickups will be loaded down by the relatively low resistance of the pot.