The Stromberg-Voisinet Company was one of the big Chicago stringed instrument makers who mass produced instruments, often for other companies which were marketed other brand names. It had its origins as the Groeshel Mandolin Company, founded in Chicago in 1890, but was renamed to Stromberg-Voisinet in 1921. Henry Kay Kuhrmeyer joined the company in 1923 and went on to become its president. In 1928, with the help of other investors he bought the company. A new company, Kay Musical Instruments was formed in 1931 from the assets of Stromberg-Voisinet.

In 1928 Stromberg Voisinet launched the first commercially made electric guitar. Their design used a metal rod attached to the bridge which moved within an electromagnet to convert string vibrations to electric current. While the earliest examples relied on batteries, by 1929 they were powered by mains electricity. This Stromberg Electro system was used to electrify guitars, banjos and mandolins.

Source: Donald Rickert - Stromberg-Voisinet and Kay (5 November 2017)

Source: Vintage Guitar Magazine September 2008. Stromberg electro. Lynn Wheelwright