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(詳細はbass buttons on an accordion, arranged to give the performer greater access to playing melodies on the left-hand manual of the instrument and to forming one's own chords, by providing a buttonboard of single-note buttons with a range of three octaves or more, in contrast to the standard Stradella bass system which only allows bass notes (range of a major seventh) and preset major, minor, dominant seventh, and diminished chords. The term "free-bass system" refers to various left-hand manual systems that provide this functionality:〔Dan Lindgren, "(Free-bass Systems Compared )"〕 * Two related layouts exist as mirror versions of the chromatic button accordion, these were marketed in the US by the Giulietti company as "bassetti".〔(【引用サイトリンク】url=http://www.akkordeon-maurer.de/documents/d/Quintkonverter.htm )〕 * The "quint" free-bass system invented by Bill Palmer - later patented by Titano, has extra bass rows to extend the existing bass arrangement of the stradella system.〔(【引用サイトリンク】url=http://www.titano.com/history.htm )〕 * The quint version and chromatic button versions were available in "converter" (or "transformer") models with a control to switch from standard stradella to free-bass.〔(【引用サイトリンク】url=http://nydana.se/accordion.html#convertorbass )〕 * A piano-like layout exists that mirrors the right-hand keyboard of a piano accordion, with round buttons laid out like piano keys. This system is popular in Asian piano accordions, especially in Azeri garmon. * Other less popular arrangements also exist, including the Moschino and the Kuehl. ==History== By the year 1900, the Stradella bass system had principally reached its current construction with 120 buttons over 6 rows. However, while that setup worked well for major and minor music accompanied by many chords, the performer would only have access to about a single octave of notes while playing - two with a timely shift of registers. The problem was solved in the early 1900s by adding three rows of chromatically ordered single notes next to the standard bass.〔Bjarne Glenstrup, ''Harmonikaens Historie'' (1972), The University of Copenhagen (Faculty of Music), p. 43〕 In 1900 in Moscow Russian master Bakanov made a garmon with piano keyboards for both right and left hands. From 1906 the brothers Kiselevs' factory in Tula began to produce bayans with the three-row free-bass left keyboard. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Free-bass system」の詳細全文を読む スポンサード リンク
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