It's all in the wood. Body inline with the neck.
Compression-deadspots-tonewood you name it....
Jaco had a crappy bridge, so it's not the hardware.....??!!
So it is the way the neck transfers the frequencies towards the body in a way that the two parts are in resonance.
Also think about the small vintage fretwire just like the 62 RI and the CS 64 Jazz; I have a custom build 55 P with a maple neck/alder body with maple top and small fretwire: less contact=warm tone.
One thing I don't understand is why the guitar-line is relatively heavy compared to the basses which are very, very, light.
Lucky for us bassplayers Fender choose a pile of fantastic lightweight alder to make the RW basses.
This must be the reason. I just can't think of another....
Forget the pickups....
Always think woodwise....................
This makes sense doesn't it????
You just know that these Fenders are gonna sound good, when you sit down with an unamplified one and feel the vibrations running smoothly through the entire bass with every note that you play
. Wonderful feeling!

