Green’s Dictionary of Slang

(orig. US black) a musical instrument, esp. an accordion, radio or juke box.

1920		H. Wiley Wildcat 55: See kin you find me a Memphis Blues in de groan box. I likes it. Cinnamon snatched a handful of melody from his guitar.
1935		A.J. Pollock Und. Speaks n.p.: Groan-box, a piano.
1937		H.B. Webb ‘The Sl. of Jazz’ in AS XII:3 183: groan box. Accordion.
c.1943		‘Bill O. Lading’ You Chirped a Chinful!! n.p.: Groan Box: Radio.
1944		D. Burley Orig. Hbk of Harlem Jive 139: Groan box — Bass fiddle.