Merci a C. E. Jackson
Gibson shipped the first Gibson Console Grande with Hyblum plates in December, 1939.
The Hyblum plates extend from the bridge, under the fret-board, and terminate at the nut.
Gibson stated that Hyblum plates are for improved tone quality and sustaining power.
Some of my favorite details are the pre-war metal plaque, the U-magnet pickups, the V-end bound rosewood fret-board, and Bakelite black and brown knobs.
Hyblum plate inserts were also used on the EH-185 and EH-275 models.
The tone quality and sustaining power are excellent.
Even with some cosmetic wear, I enjoy playing this historic instrument (and it's heavy).
I currently have the 7 string neck tuned to A6, and the 8 string neck tuned to the Don Helms E6