There is no real consistency on triple-pickup basses. Every player has a preference for control schemes, whether there are two pickups, or three. IMO, a switching-based scheme would be best, given the dissimilar output impedances of the pickups. Having multiple volumes is just going to cause weird interactions and volume drops.
Also, you can't have three tones on a passive bass, unless you isolate the signal paths with resistors, because they will all behave as masters, since they run parallel to the signal path. The trouble with the resistors is that they will decrease the output of each pickup. OTOH, you may be fine with the interactions between tone controls in a switch-based scheme, since the pickup selector switch will bypass some controls, depending on the setting.
Last edited by line6man : 12-10-2013 at 12:24 AM.