I've been thinking about changing the pickups on my bass. The bass is a passive Corvette standard with Jazz-type pickups and three controls; Tone, balance and volume. I have no idea whatsoever about pickups and what brands are quality. So, please help me with this: What brands are the best, qualitywise? Is it possible to make my passive bass active? How? Can I do the installation myself? Are there any homepages with brands/info? thanks.