Once upon a time, electric violin company Zeta was based in San Francisco, and very briefly had an acoustic/electric mandolin in its line—which from all appearances was just a rebranded Asian-built F-style.
     As of 2016, however, Zeta belongs to former Flatiron mandolin builder Steve Carlson and is located in Montana. After finishing his first run of 44 violins, Steve branched out into his old territory and designed the JM25, an acoustic/electric 5-string mandolin that's fully MIDI compatible.
     Then, in 2020, Zeta introduced the Stage line of mandolins: an A-style (and soon an F-style) that is the first fully acoustic mandolin to incorporate Zeta's patented Strados bridge design. It's available in both acoustic/electric and purely acoustic configurations.