I'm building my own bass and have finally gotten to the electronics part. It is a 6 string fretless but the string spacing is too large for normal pickups and I had to go with a set of Bartolini 7-string bass pickups (http://www.bestbassgear.com/bartolini-g67-pickups.htm). I've soldered one or two other instruments before and was able to tell which wire was which but with these I'm not able to distinguish like before. There are two wires coming out of the pickup: one with a clear shell and the other is just a bundle of wires (picture of what I'm talking about in the link above). This is the first time I've seen something like this. Which wire is the ground wire? I've only had experience with the usual black/white wires coming from the pickups.