What is wrong with the adjustable bridge on a J50?
what's right about it? :)
a bunch of heavy steel and brass nuts and bolts and screws and bushings to support a saddle of either soft wood or heavy ceramic with a big air gap under it, all to avoid the few minutes of factory setup time to adjust a properly fit non-moving saddle to the right height.
those guitars can sound good, but they do so despite that contraption, not because of it.
what's even worse is when you have all that junk on a hollow plastic bridge, there's no support for the structural strength of the top.
at least if the bridge is wood you can replace the contraption with a wood and bone insert that fits solidly and will improve the tone.
something like this:
in this case gibson had hit upon something that might have been worse still, a tune-o-matic off an electric guitar!
it was much louder and better-sounding with the bone saddle insert and on this otherwise amazing old dove the guitar was still totally unaltered and reversible to stock.
Or, install a K&K Mini on the bridgeplate, and you won't need to touch the existing adjustable saddle.
y'know, even then i'm not so sure it would do that great.
the three elements of the mini are driven by fairly direct vibration from the bridge saddle sitting directly over them, that's why they get a surprisingly loud and focused signal from the strings for a bridgeplate pickup.
with an adjustable bridge that direct vibration is entirely missing, the saddle attaches to the bridge only on the ends, well outside the area that the K&K is expecting to get signal from.