Fellow Tone Chasers,
The reference guitar used to build most of our profiles is a 1954 Gibson Les Paul Goldtop (serial number 4 4991) which was modified with original 1950's Gibson PAF pickups and a Tune-O-Matic bridge. I guess that makes is a "1957 Conversion", since it's basically been modified to '57 Goldtop specs. I know -- you shouldn't go hacking up an expensive vintage '50s Gibson, but my conscience is clean (I didn't do the conversion) and I get to reap all the benefits.
This particular guitar was purchased at Carter Vintage Guitars in Nashville by none other than Robben Ford around August 2017. Conversions are popular because you get the look, sound and feel of a late 50's LP without needing to take out another mortgage. They're still not cheap by any means, but roughly an order of magnitude cheaper than an original.
Here's Robben playing a '52 Goldtop that he traded in for the '54 on the left, which is played by Jeff Mcerlain. The '54 had some kind of non-original bridge installed and removed during its lifetime, leaving some scars and making it more suitable to a conversion than a pristine example would have been.
The guitar first went to Tom Murphy to have the finish stripped off in preparation for the conversion work. According to Tom, the original finish on the guitar was extremely thick. At the Gibson factory, if, while removing the finish from the binding, the finish got nicked, the whole top of the Goldtop was completely re-painted. Tom estimated the finish had been applied 3 times to this guitar and that it was about 1/8" thick. Carter Guitars was concerned that the finish might not have been original, but Tom says it was.
The guitar was then brought to Glaser Instruments in Nashville for the conversion work. The body was routed for PAFs and a Tune-O-Matic installed. The original bridge was reused as the stopbar tailpiece for the new bridge. I must say, the work was impeccably done. It would be hard to tell it didn't originally come this way. It was also re-fretted and Plek'd at the shop. It plays like butter.
The guitar then went back to Tom Murphy for finishing. He completely refinished the top including an amazingly realistic relic treatment. The guitar retains the original factory gold finish on the back of the body and neck. This was done if the wood had a visual defect they wanted to hide. The finish on the back of the neck on all-gold Goldtops tends to chip over time and become rough to the touch. Tom smoothed out the finish on the back of the neck at the request of Robben.
After about a week of playing the guitar, Robben asked Tom if he could replace the inlays on the fretboard, as his fingernail was occasionally sticking between the inlay and the rosewood. Tom instead applied some epoxy (or similar) around the inlay to eliminate the problem (and save the original inlays!). The guitar still has its original inlays.
Here's Robben using the guitar after the conversion.
Tom said Robben really liked this guitar, but had his eye on a burst so it had to go.
When I received the guitar, it had a rounder tone with less high-end sparkle than I expected. Great for jazz, but not for much else. After purchasing this expensive (to me, at least) guitar with the intent of using it as a gold-standard (pun intended) tone reference, I was freaking out a bit. The old-growth Honduran mahogany and original PAFs should have been tonal nirvana. It also had 1950's tone caps, which go for good money as well.
I investigated the volume and tone pots, and found the issue. Potentiometers can have resistance value tolerances of up to +/- 20%. So, a pot marked 500K can range in value from 400K to 600K. The pots all measured right around 400K, which means they squeaked by quality control and made their way into my Les Paul in 1954. Low valued pots effectively reduce the high frequencies coming out of the guitar. Unfortunately, the guitar was basically unusable to me with the original pots, so I had to swap them out for pots much closer to 500K. The sparkle is now there, and the tone is now all that I had hoped for. I have no evidence, but I'm guessing the original 400K pots and dull tone might be why Robben decided to sell the guitar.
Anyway, that's what I know about the "Gold Standard", 4 4991. It's amazing to own an instrument like this. I haven't been guitar shopping since.