recording disc of the Imperial surrender message
Historical term referring specifically to the phonograph record of Emperor Hirohito's 1945 surrender announcement, ending World War II.
The gyokuonban is the record on which the Imperial Rescript on the Termination of the War was recorded.
From 玉音 (gyokuon, 'the Emperor's voice') + 盤 (ban, 'disc/record'). The term is historically tied to the 1945 surrender announcement.