The National Reso-Phonic company re-issued the steel body models in 2009, in both 12 and 14 fret designs.
![national duolian guitar case national duolian guitar case](https://guitars.azureedge.net/aza/user/gear/1936-national-duolian-gray-duco-6-0B9Ve77.jpg)
The ‘Duolian’ was a very similar instrument, but with less decoration, and an unbound mahogany neck.
![national duolian guitar case national duolian guitar case](https://guitarpickersaz.com/wp-content/uploads/2021/10/front-1.jpg)
This proved too complex, and so the design, but not the name, was changed to the single cone we see now. The ‘Triolian’ name is a holdover from the name given the original prototypes, which had a trio of small resonators under one round coverplate. Some players find that the larger body on the 12-fret model provides a slightly deeper tone and the 14-fret a little more ‘bark’. This 14-fret body evokes an ‘OM’ (Orchestra Model) shape, while the original 12-fret model resembles a slope-shoulder dreadnought. In late 1934, the neck was changed to a 14-fret design, and to accomodate this, the body was ‘shortened’ – the scale length is the same at 25 inches, so there is no difference in string tension. For much of the first year, a Bakelite neck was used but this miracle material turned out to be unstable and was replaced with maple. Originally a wood-body guitar with a single resonator cone, in 1929 the Triolian was given a steel body. The National Triolian was originally introduced in late 1928 and built until 1938. In 1928, the single-cone design was introduced as a way to cut production costs, but this met great controversy within the company. The first instruments used three small cones – the classic Tricone design.
![national duolian guitar case national duolian guitar case](https://thumbs.static-thomann.de/thumb/thumb600x600/pics/bdb/276776/6427240_800.jpg)
The National String Instrument Corporation patented and produced the first resonator instruments in 1927, responding to the constant need for more volume. Available in original style 12 fret or 14 fret necks, these guitars produce a full, rich and lush vintage tone. The National Resophonic company presents the National Resophonic Triolian, featuring a steel body with walnut burst finish and a single cone.