.. a Swedish cabinet maker, went to Boston Mass. in 1887.  He secured work in the Thompson & Odell works and for eighteen years was their foreman in the banjo, mandolin and guitar factory.

In 1905 he started his own business at 40 Hanover St., Boston, and five years later took his son Elmer into the business with him. Between them the two craftsmen produced hundreds of banjos, including other musical instruments in which they specialised.

The banjos they produced and sold under the name of Stromberg had what they called a “Cupperphone Tone Chamber” which consisted of a metal ring placed on a series of upright metal tubes or cups fitted on a built in wooded shelf inside the banjo hoop and directly under the vellum.

The firm appears to have gone out of business soon after 1929  

Photos courtesy of Intermountain Guitar & Banjo