"Graphophone" is indeed the correct spelling.  Wrong versions are
so common that the right spelling looks like an error!

Slightly off-topic:  The Columbia Graphophone Co. and the Gramophone
Company merged in 1931 to make Electrical and Musical Industries (EMI).
Apart from both companies having factories in Hayes, Middlesex, was
there ever any connection between EMI and Aeolian?

Jeffrey Borinsky