Since someone mentioned it:don’t overlook the brightness of a bolt on..
My experience is very limited compared to youse guys, but when I recently became inflamed by this topic, and changed the neck on my new F Am Pro J Bass from 1.5"/.8"/.9" to an Allparts PMO 1.625"/.92"/1.0", the unwanted brightness disappeared and the lows and richness came up (all over the neck it seemed to me), and only then did it become comparable to my GLARRY.
The mysteriously great sound of the Glarry had been one hint. Another was that a capo on the second fret (tuned to E with the capo installed) also almost fixed that J. Expensive lesson.

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