Semi-acoustic refers to an electric guitar with a solid center block but acoustic chambers in its outer body wings. You’d think that semi-acoustic guitars would have arrived as an evolutionary step between the acoustic archtop electric of the 1930s and ’40s and the solidbody of the early ’50s, but they arrived good and proper with Gibson’s unveiling of the ES-335 model in 1958.
Gibson had released new thinline acoustic archtops (those with thinner than usual bodies) in 1955 and ’56 in the Byrdland, ES-350T, ES-125T, and ES-225T, all intended to be easier to play than the big-bodied jazz boxes. Gretsch unveiled its own somewhat reduced-bodied acoustic electrics, like the 6120 (the Chet Atkins Hollowbody).
As the solidbody electric gained in popularity, however, guitar makers wanted to capture some of the benefits of those designs in a guitar that would appeal to more traditional tastes. The ES-335 did exactly that — it was an instant hit as a result and has remained one of the most influential electric-guitar designs of the past 50-plus years.
The majority of semi-acoustic electrics, including those already mentioned, have glued-in necks and share certain sonic characteristics with set-neck solidbodies, while, unsurprisingly, taking other characteristics from archtop acoustic-electric guitars.
Similarly, some — notably Rickenbacker’s 360 and its siblings — had through-neck construction, although the pickups and other components used on them tended to take them further from what’s traditional for that template. A few semis, such as the Fender Coronado and Harmony Rocket and the ilk from the 1960s, had bolt-on necks, which often contributed to a somewhat snappier, janglier tone.
Although it’s something of a misnomer, players and manufacturers today often use semi-acoustic or just semi for short to describe both guitars that have solid center blocks and those which are fully hollow but have thinner bodies than normal full-sized acoustic archtops.
True semi-acoustic electrics constitute an extremely popular category — thanks in large part to such guitars’ often-impressive versatility, as well as the light weight that can result from many such designs — and the world of semis continues to boom in an array of creative new makes and models that fill a wide range of players’ needs.