The most common accordion in the United States is a piano accordion. Click on the link to access a diagram.
The treble (piano) keys are played by the right hand. The standard accordion has 41 keys, 24 white keys and 17 black keys, ranging from a low F to a high A. Each key controls two reeds. Sound is produced as the bellows push or pull air through steel reeds. In a piano (chromatic) accordion, the push and pull produces the same note. By contrast, in a diatonic accordion, typically button accordions such as cajun or Tex-Mex, the push and pull produce different notes (like a harmonica.)
By the 1880's, accordions began to have sets of reeds in reed blocks. By the press of a button or switch near the treble keyboard, a different set of reeds, can be activated. Reeds generally can produce a low, middle or high sound. A musette (vibrato) sound requires two middle reeds tuned slightly apart. By 1955, the accordion manufacturers agreed upon a standardized name and symbol for each set of reeds, as show on the chart below.
By the late 1800's, the left hand buttons were commonly arranged according to the circle of fifths with six rows of buttons: The second row (from the bellows) is the "fundamental bass," i.e. C, G, D, A, E etc. according to the Circle of Fifths. The C button is usually marked by a depression or ridge. Often the Ab and E buttons in the fundamental bass row are also marked with a ridge. The row above the fundamental bass (next the to bellows) is the counter-bass row, a major third above the corresponding fundamental bass button. The next four rows are the major, minor, dominant seventh and diminished chords. This was known as the stradella system. By the way, bass is pronounced "BASE" as in baseball, not bass as in the fish. The bass chords do not accomodate a 5th Thus, a C7 chord is usually C-E-G-Bb. The accordion generally omits the G (which is the weakest sound). Click on the like to access a chart of the 120 button stradella bass system:
Like the treble key reed blocks, differnt bass reed blocks can be activated by pressing a switch or tab on the bass side of the accordion. A diagram of bass reed switches follows:
More under construction
Guido Deiro is credited with introducing the piano accordion to the United States.
More Under Construction