Older instruments sound better, ate this true and why

[Scott Pope]

The conventional wisdom for all acoustic instruments is that as the wood vibrates it loses its "tightness" and resonates better, and that as the sap dries out further over time this also contributes to the resonance improving. I've not had the pleasure of owning a double bass long enough for this to happen, but it definitely has occurred on my two acoustic guitars I've owned for years, one fairly inexpensive, and one fairly expensive, the common denominator being that both have good quartersawn spruce tops to begin with.

As far as solid body instruments, hindsight is everything. I'm sure there are some good basses out there which, again, due to the wood continuing to cure over time, sound better as they age. But -- I'm not so sure about the electronics. Parts corrode, coil wire insulation can break down, the dielectric of capacitors can break down, and magnets (rarely) can lose their gauss. It's my opinion that when it comes to solid body electric basses, that the old good ones are good because they were good to begin with, with well seasoned wood and good quality electronics properly executed into an instrument at the beginning, not through the aging process.