Violectra is the trade name of an electric violin produced by Barcus-Berry with the pitch equivalent of an acoustic tenor violin, sometimes called baritone violin. It is tuned an octave below normal violin; i.e. between viola and cello. It was developed in USA by Barcus-Berry in the early 1960s but maybe not perfected (so to speak) till a bit later. Jean-Luc Ponty was one of the first famous jazz violinists to play it, Michał Urbaniak and Elek Bacsik too. Fiddler Vassar Clements has brought the instrument into the progressive bluegrass scene. Urban Blitz introduced the instrument into the rock music context.
The first recording known of with it is by the maker himself John Berry on a 1963 demonstration album. It was probably used by some LA studio musicians before the jazzers got hold of it.