We all chuckled when Marty got ready to do a riff in front of this giant speaker… I think everyone knew what was going to happen.

This one – a Diatone speaker from Mitsubishi – was even larger. Diatone was a loudspeaker division of Mitsubishi Electric. The first ones were built in Spring of 1945 for the Japanese radio station NHK; the division closed in 1999.