My old Jazz 4 bass weighed 12.5 lbs.
My Pedulla 5 (bolt on) weighs 9 lbs,
much bigger sounding.
^But that's not even comparing similar basses at all.
For someone like Timmy C to say something like that since he has a fleet of all the same bass, is probably what he's getting at.
I have always owned multiples of the same bass. And to me the heavy beasts seem to have a harder attack and tad better sustain. But to me the lighter ones of the same model of bass have warmer mids, and I've tended to use better for recording.
