I started out wanting to see if I could eliminate some undesirable “noise” from my Fender Jazz Basses, the story took a few turns…
I was mostly concerned about the active bass because the noise was so prevalent to my ear in the upper eq range I had completely stopped using it altogether (and it’s a really nice bass). Considering I wanted to use the bass for studio work and recording, it being as quiet and noise free as possible is a prerequisite. The bass has such a great feel and sound, and I like the compound radius neck that seems Fender only produced for a couple years, making this bass somewhat unique.
I thought the first step would be to make sure all the internal electronics were shielded from outside Radio Electro Magnetic Interference. The idea is to isolate everything within a Faraday Cage. This is accomplished with some type of carbon metallic conductive paint, or some type of metal foil. In this case I used copper foil tape with a conductive adhesive. After all the components are removed we can begin building our “force field”.
One of the important things that can be easily overlooked is assuring continuity between all the different cavities inside the Faraday cage so I soldered a ground wire from each section to eliminate any doubt that they were all electrically connected. I also lined the underside of the control plate with copper to help ground all the control knobs and made sure not to forget the underside of the pic guard. I thought overlapping the copper tape on the bass body would also be helpful in achieving maximum continuity with the control plate and pic guard.
Using the pickup cover upside-down was extremely helpful in getting the copper tape to conform tightly to the inside of the bridge pickup cavity. After shielding everything and making sure I had good continuity (using a multi-meter) to the bridge as well everywhere copper was placed and pieces joined together, I replaced the preamp and pickups.
I put the bass back together with all original components. Plugged it in, cranked it up, and was hoping my bothersome noise would vanish. Although it was diminished slightly, it did not go away. I already had an Aguilar OBP-3 bass preamp on hand I was considering installing in this bass, or my other passive Jazz Bass; and I was also in the process of shielding my other (passive) bass, so needless to say I began to brainstorm. Music Plays Me!
Active Jazz Bass (Ash/Maple) 
Passive Jazz Bass (Alder/Rosewood)