Abstract: A stringed musical instrument with fixed frets is provided with the capability of employing more than one tonal scale. At least two fretted fingerboards are provided with frets located at different relative positions on the respective fingerboards. A transversely opening groove is formed on the instrument beneath and parallel to the strings. On the underside of each fingerboard, a corresponding groove is provided which opens transversely with respect to the fingerboard. Each of the fingerboards can be mounted to the instrument when desired by engaging the groove on the selected fingerboard with the corresponding groove on the instrument. A mechanism is provided for forcing the grooves together so that the fingerboard is secured to the instrument in a releasable fashion.

Abstract: A fretted stringed musical instrument with a readily removable fingerboard to enable performance of musical compositions written in different tonal scales by removing a fingerboard having fret placement in accordance with one tonal scale, e.g. equal tempered scale, and installing another fingerboard having fret placement in accordance with a different tonal scale, e.g. just intonation scale.Several alternate arrangements permit a given fingerboard to be quickly installed or removed without removing or slackening the strings so that fingerboards may be exchanged in the course of a concert to permit performance of musical pieces from several tonal systems on a single basic instrument.