In the 1920s, Dopyera opened his own store in Los Angeles where he worked making and repairing fiddles, banjos, and other wooden string instruments.
In 1925, Dopyera was asked by vaudeville instrumentalist (and, later, pioneer developer of electrically amplified instruments) George Beauchamp to create a louder guitar.
Dopyera and his brothers Rudy and Emil, as well as other investors, founded the National String Instrument Corporation to manufacture the new type of "resophonic" guitar, which was sold mainly to musicians working in cinemas and jazz clubs in the USA.
As illustrated with the Bantar, John removed the "Y" from the Dopyera name, when labeling his new instruments, as he reasoned that "Dopera" was easier for the public to understand and pronounce.
[3] The Dopyera brothers later moved to Chicago, where they made millions of dollars with the Valco music company and other business interests.
The design cut through all musical boundaries, however, proving equally at home in folk, rock country, blues and jazz.