Stradella bass system
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The Stradella Bass System (sometimes called standard bass) is a buttonboard layout equipped on the bass side of many accordions, which uses columns of buttons arranged in a circle of fifths; this places the principal major chords of a key (I, IV and V) in three adjacent columns. Each column contains, in order:
- The major third above (or minor sixth below) the root ("counter-bass")
- The root note
- The major chord
- The minor chord
- The dominant seventh chord
- The Diminished seventh chord
The following chart shows a common 120-button Stradella layout.
In modern accordions, each chord button sounds three individual pitches. Early accordions sounded four pitches for the seventh and diminished chords. Modern Stradella systems omit the 5th from these two chords, allowing for more versatility. For example, an augmented seventh chord can be created by using the dominant seventh chord button and adding an augmented 5th from the right-hand manual or from one of the bass or counterbass buttons.
In most Russian layouts the diminished seventh chord row is moved by one button, so that the C diminished seventh chord is where the F diminished seventh chord would be in a standard Stradella layout; this is done in order to achieve a better reachability with the forefinger.
The larger and more expensive accordions can also have on the Stradella bass side, some Register switches, similar in concept to the treble register switches.
- Fingers are numbered 2 to 5, starting with the index-finger. The unused thumb is numbered 1, to match right-hand fingering;
- Scales are played on the first two rows (root-row r, and thirds-row t), starting with the ring finger on the root-row (r4);
- The hand does not have to move during major scales;
- r4 r2 t4 r5 / r3 t5 t3 r4.
|Name||Columns||Rows of bass-notes||Rows of chords|
|8-bass||4 - Root notes: F to D||Root note||Major|
|12-bass||6 - Root notes: B♭ to A||Root note||Major|
|24-bass||8 - Root notes: E♭ to E||Root note||Major, minor|
|32-bass||8 - Root notes: E♭ to E||Root note||Major, minor, 7th|
|40-bass||8 - Root notes: E♭ to E||Major 3rd note, root note||Major, minor, 7th|
|48-bass||8 - Root notes: E♭ to E||Major 3rd note, root note||Major, minor, 7th, diminished|
|12 - Root notes: D♭ to F♯||Major 3rd note, root note||Major, minor|
|60-bass||12 - Root notes: D♭to F♯||Major 3rd note, root note||Major, minor, 7th|
|72-bass||12 - Root notes: D♭ to F♯||Major 3rd note, root note||Major, minor, 7th, diminished|
|80-bass||16 - Root notes: C♭ to G♯||Major 3rd note, root note||Major, minor, 7th|
|96-bass||16 - Root notes: C♭ to G♯||Major 3rd note, root note||Major, minor, 7th, diminished|
|120-bass||20 - Root notes: Low A to A♯||Major 3rd note, root note||Major, minor, 7th, diminished|
|120-bass||20 - Root notes: Low A to A♯||Minor 3rd, Major 3rd, root note||Major, minor, 7th|
|140-bass||20 - Root notes: Low A to A♯||Major 3rd note,[notes 1] root note||Major, minor, 7th, diminished, augmented[notes 1]|
|160-bass||20 - Root notes: Low A to A♯||Three major 3rd rows, root note||Major, minor, 7th, diminished|
- 140-bass accordions may come with either an extra minor 3rd note row, located above the regular major 3rd row and the root note, or an augmented 7th chord row.
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