In 1927 the National String Instrument Corporation was formed by John Dopyera, the luthier who had invented the resonator guitar, and George Beauchamp, the steel guitar player who had suggested to Dopyera the need for a louder guitar able to play a melody that would be heard among brass and other wind instruments. In 1928, Dopyera left National, and together with four of his brothers formed the Dobro Manufacturing Company to produce a competing single resonator design, with the resonator cone inverted. John Dopyera continued to hold stock in National. In 1932, the Dopyera brothers secured a controlling interest in both National and Dobro, and merged the companies to form the National Dobro Corporation. Until today National continued to build Guitars and amplifiers.