Developed by Dr Michael Kasha and luthier Richard Schneider, the aim of this soundboard design is to optimise the features of the soundboard/bridge, to better respond to the vibrations produced by the strings, in order to produce instruments that have greater sound clarity and better sustain. The design theory involves a significantly greater amount of physics than the traditional fan braced design, and has a number of key design features:
Firstly, instead of having a relatively symmetrically braced soundboard, the soundboard is braced so that one area responds to treble frequencies, while another responds to bass frequencies. This is achieved by having radial coupling braces extending out to different lengths from around the area of the bridge. On the bass side of the bridge, the tone bars extend significantly longer, all the way into the soundboard upper bout, while on the treble side, the tone bars are significantly shorter. The treble side of the soundboard is further braced with treble confinement bars, which extend around the ends of the treble tone bars.
The second significant feature of the Kasha/Schneider theory is a wedge shape impedance dependant bridge. The shape of this bridge is specially designed to further optimise transfer of energy from the strings to the soundboard, by driving the bass tones into the bass side of the soundboard, and treble tones to the treble section.
The third significant feature of the Kasha/Schneider theory is to shift the soundhole from the centre of the soundboard, to the upper bout on the treble side. This increases the effective area of the soundboard that is available for vibration and sound production, and also reduces the loss of soundboard strength generated by a soundhole.
The Kasha/Schneider theory has been applied to ukuleles by luthier Michael Chock from Hana Lima ‘Ia, with a series of slight modifications to adjust the idea to be more suitable for the smaller body size. The principle of the modified Kasha/Schneider bracing system adopted for the MAKAIO TKL003 Tenor Kasha Ukulele comes from the plans produced by Hana Lima ‘Ia.