Eighty-five years ago, the gentleman shown here spinning the records put his entrepreneurial skills as well as his tech savvy to work with this portable sound system he designed. He is one Fred Dingman, who authored two construction articles about how to build the sound system in the November and December 1939 issues of Popular Mechanics.

He reported that the investment was only about $25, as all parts are inexpensive, and he built the enclosures himself. The finished circuit put out 10 watts of undistorted sound to two 12-inch speakers, meaning that he could provide adequate volume for small halls or outdoors. It was designed as an inexpensive substitute for small dance orchestras, and he had no difficulty obtaining engagements for fraternity and sorority parties, dancing clubs, or lawn gatherings in a middle west university town.

At a reasonable rate, he provided the equipment, operator, and records. For those wishing to follow in his footsteps, the magazine could provide a complete set of blueprints.  The system could also accommodate a microphone.