Paul Barth (of Rickenbacker and Magnatone) founded the Bartell company (alongside Ted Peckels) in the mid 1960s following his time at Magnatone. Bartell instruments were made from 1964 to 1969, with about 2000 made in total. The Bartell company were also an OEM maker for Hohner, St. George, and Lancer. Some Hohner Black Widow basses have "Hohner" on the headstock but a label in the f-hole states "Mfg. by Bartell of California". Bartell also made some St. George brand guitars.

Source: Bartell fan site