Free-bass system

A free-bass system is a system of left-hand bass buttons on an accordion, arranged to give the performer greater ability to play melodies with the left-hand and form one's own chords. The left-hand buttonboard consists of single-note buttons with a range of three octaves or more, in contrast to the standard Stradella bass system, which offers a shorter range of single bass notes, plus preset major, minor, dominant seventh, and diminished chord buttons. (Pressing a single preset chord button sounds a three-note chord.) The term "free-bass system" refers to various left-hand manual systems that provide this functionality: The Stradella system does not have buttons for different octaves of the bass notes, which limits the types of melodies and basslines that can be performed with the left hand. Two related layouts exist as mirror versions of the chromatic button accordion, these were marketed in the US by the Giulietti Accordion Company as "Bassetti".