Martin is one of the oldest guitar makers around, established in 1833 in New York (C.F. Martin's father was a guitar maker as well, in Europe). Known primarily for its flattop guitars and especially as the designer of the ever-popular dreadnought shape, Martin first listed tenor guitars in 1927. The O-18T tenor was popularized in the late 1950s by Kingston Trio member Nick Reynolds.
Martin Tenor Guitars
Martin made tenor and plectrum models (with a T or P after the model name), the first of which was a 5-17 in 1927 (which did not have the T after the model name). The first digit in Martin model No.s refers to the body size, and the 2-digit No. is the "style" No. (style 18, etc.). The O-size tenor actually as a smaller body than the O-size 6-string. Martin now only offers the O-18T as a custom shop model. Styles 15 and 17 have mahogany tops and sides; All other styles have a spruce top.
O-18T (1929-present), spruce top, now available only by special order from the custom shop. 31 were made in 1930 under the Carl Fisher brand. This instrument is commonly associated with Nick Reynolds of the Kingston Trio, who also played an O-17T (later converted to an 8-string, something he had done to an O-18T as well) and occasionally a 2-18T.
(1997), part of the Kingston Trio Limited Edition, consisting of 40 sets of three instruments (the others being the D-28KT six-string, and a Deering Vega long neck banjo).
O-18T8 eight-string version of O-18T (five made, 1969-70)
O-18TE electric version of O-18T (two made, 1959 and 1962)
O-18TD (one made, 1976)
O-17T (1932-1960) all mahogany, rosewood fingerboard and bridge.
O-28T herringbone (1930-31; one each made, 1941, 1961, 1964) spruce top, some have banjo style tuners
O-21T (three made, 1929; two made, 1930 and 1935; one made, 1961) spruce top
O-15T (1960-63) all mahogany, rosewood fingerboard and bridge.