| You could just try it both ways and see what it sounds like.
Try it one way, and if the pickups sound thin and nasaly when played together, flip the leads around the other way.
FWIW, pickups don't have positive and negative wires, per se.
The signal coming from the pickup is an alternating current, which means that the positive and negative reverse themselves periodically, depending on the frequencies of the signal.
The terms positive and negative are only used in reference to the phase when two or more coils are used. |