You're welcome.

Looks like they patented their cone materials and process;

IXHJD SPEAKER - Google Patent Search

Had to look up "buckram". A stiff, formable woven, starched cotton or linen, long used to make hats, now mostly as textbook covers. G-G's cone patent used aluminum & graphite powder in laquer to coat the buckram for added mass.

Must have been good stuff, that cone looks pretty nice for 80 years old.

Added
Just noticed- by the time their patent was granted (8/33) G-G was already bankrupt.