Random Cliff Burton fun fact #54
(this is mainly about his Rickenbacker)
Cliff's Rickenbacker was very modified
Apparently, his original stock pickups couldn't handle the aggressive style and effects setup Cliff used, he had to swap them out. The neck pickup was also replaced with a Gibson EB-0 "Mudbucker"
The bridge was a Seymour Duncan "Classic Stack Jazz Bass". Also, Cliff had a third Seymour Duncan Stratocaster pickup installed in the place of the Rickenbacker's foam mute. This third one was wired to a push-pull switch on one of his bass's tone knobs (he didn't really use it for standard rhythm playing though, mainly used for his solo boost)
Since that pickup was a guitar pickup positioned right up against the bridge, it captured a very bright high-end frequency that extra treble edge helped the bass cut through the mix with a piercing scream which sounded more like a rhythm guitar instead of a bass
Information from basshabitspdb on Instagram!