National resonator instruments introduced in 1927 were louder than conventional acoustic guitars of the era and where the first result of the research to amplify the sound of the guitar. They were very popular with Hawaiian and Blues musicians in the late 1920's and early 1930’s. The resonator guitar was fundamental to the evolution of bluegrass music. The design cut through all musical boundaries, however, proving equally at home in folk, rock country, blues and jazz.
The team behind the development of the resonator guitar went on to develop the electric guitar. In 1927, John Dopyera, a Slovak immigrant, and George D. Beauchamp, a vaudeville musician and promotor, formed the National String Instrument Corporation to manufacture resonator guitars under the brand name National, adding tenor guitars, resonator mandolins and resonator ukuleles to their product line within a year. Dopeyra left the company in 1929 to form with his brothers the Dobro company, producing similar instruments.
The resonator guitar was originally designed by John Dopeyra to be louder than conventional acoustic guitars.
National's produced two types of resonators: The single cone and the tricone. Those instruments use very thin aluminium speaker cones, to mechanically amplify the sound of the instrument. This style of mechanical amplification was invented in the 1920's, before the advent of electric instruments.
In a tricone, the three 6" cones are set in a triangle. Two of the cones are on the bass side, and one on the treble side. Rather than a wooden biscuit bridge, there is an aluminum "T" shaped bridge that connects to the center of each of the cones. A maple wooden saddle sits atop the T-bridge. The vibration from the strings goes through the saddle, which in turn vibrates the T-bridge, and then the three cones. The sound has farther to travel to get the cones resonating than with a single resonator guitar. Thus, that's why tricones are not as loud on the attack. However the sustain is greater, and the tone "sweeter". This is because there are three cones all vibrating together, producing more harmonics than a single resonator guitar.
Resonator guitars had either Square neck (D) or Round neck (C) depending on how the guitar was supposed to be played. The square neck was for playing the guitar as a lap steel guitar, whereas the round neck was for the paying the guitar in conventional manner.
This very early first year production guitar, with still "patent pending" marked on the guitar, was still hand made by the Dropeyra brothers and is the 79th guitar built. The guitar features a German silver body (solid nickel alloy with nickel plating), three or "tri" resonator cones with two cones on the bass side, one cone on the treble side, T-shaped bridge cover and hand rest, hand woven grid pattern sound holes on upper body, Hawaiian square neck, 12 frets clear of the body, flat fingerboard radius, metal neck with mahogany headstock, bound single layer ebony fingerboard and a slotted peg-head.