Who released 7" microgrooved records in the 1950s?
One of the first attempts at this was in the 1950s, when inventor Ewing Dunbar Nunn founded the label Audiophile Records, which released, in addition to standard 33 1/3 rpm LPs, 78 rpm-mastered albums that were microgroove and pressed on vinyl (as opposed to traditional 78s, with their shellac composition and wider 3-mil sized grooves).