Both the music room in my house and the room where my band rehearses have a lot of electrical crud in the air, so single-coil pickups don't work well there. For a Rickenbacker 4000-series bass, these JBE pickups are the answer. They're about as easy to install as you could expect (Rickenbacker's idea of how to mount pickups is a little unusual, especially for the bridge pickup), but follow the printed instructions and you should be fine. There is no need to replace the factory pots; the pickups sound fine with them. And most importantly, they sound like Rickenbacker 4000-series pickups should, but without the hum. Strong bass, treble grind: it's all there.
JBE includes a new mounting frame for the neck pickup, but you re-use the chrome pickup covers from your standard Ric pickups. The bridge pickup's position is adjustable, which allows you to ensure that the pickup is centered across all four strings. I had found with the factory pickups that the neck pickup was not as loud as the bridge (I tried raising the neck and lowering the bridge, which helped, but not enough) and the first string sounded slightly weaker than the others. With the JBE pickups, the neck/bridge balance is better (though the bridge is still a bit louder when the high-pass filter is disabled) and all four strings are well-balanced.
The only negative thing I have to say about these is that they are a little of pricy at $300, though that's not out of line for a pair of boutique pickups.
Jbe R-4000 Style For Ric
Joe Barden humbucking pickups for Rickenbacker 4000-series basses