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.
Each bass note, and each pitch in a chord, is usually sounded simultaneously in multiple octaves. Larger accordions offer some control over the voicing with register switches.
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.
When naming chord buttons, major chords are often suffixed with "M", for example "CM", to distinguish them from bass notes.
In staff notation, notes below the center of the bass-clef staff are bass notes, and notes above the center of the staff usually indicate chord buttons, labeled as necessary with "M", "m", "7", or "d" or "dim".
Within this convention, the written octave for bass notes is arbitrary, as the Stradella system does not have buttons for higher and lower octaves.
As sounded, with one possible octave voicing:
Bass notes to be played on the major-third (counterbass) row are indicated by repurposed "tenuto" lines below the notes (as in the E bass note in the example above), or underlined note names or numbers.
Single-note bass lines are often labeled "B.S." (bass solo or bassi soli), especially when they extend above the middle of the staff.
As with the piano, fingers are numbered 2 to 5, starting with the index finger, mirroring right-hand fingering. As a rule, the thumb, numbered 1, is not used.
Patterns can be played identically in any desired key, changing only the starting position; this is because unlike a piano keyboard, the Stradella layout does not distinguish between "naturals" and "sharps".
Bass and chords
4-3 is a recommended fingering for a bass note and its corresponding major chord (e.g. C-CM-C-CM). For alternate bass with the root and fifth, 4-3-2-3 can be used for major chords (e.g. C-CM-G-CM), 4-2-3-2 for minor and other types of chords (e.g. C-C7-G-C7).
Scales, runs, and other bass lines are played on the two rows closest to the bellows (root row and thirds row).
The major scale can be fingered without stretching the hand, playing "do re mi fa sol la ti do" in any key as r4 r2 t4 r5 / r3 t5 t3 r4 (r = root row, t = thirds row) or, with minimal movement of the index finger, r3 r2 t3 r4 / r2 t4 t2 r3.
A recommended fingering for harmonic minor:
Melodic minor (different ascending and descending):
Larger and more expensive accordions may have as many as seven register switches on the Stradella bass side, controlling the octaves and voicing of the bass notes and chords, similar in concept to the treble register switches. Smaller or simpler accordions may have no bass switches, or a single switch that toggles between two settings.
|Register Switch||Reed Sets|
|(chords and bass notes)||(bass notes only)|
or Bass Forte
or Bass Piano
With the Soprano or Alto register selected, bass buttons exactly duplicate individual notes from the chords, without the usual added lower octaves.
An accordion with two register switches on the bass side might provide Tenor and Master registers, while accordions with additional switches might have larger subsets taken more-or-less from the middle of the table above.
|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.
- Balestrieri, Donald (1979). "Registers of the Standard Stradella Keyboard". Accordions Worldwide. Retrieved 24 August 2014.
- Zucco, Frank (1985). Mel Bay's Deluxe Accordion Method. Pacific, Mo.: Mel Bay Publications. ISBN 978-0871667823.
- Dahl, Gary (2004). Mel Bay's Master Accordion Scale Book With Jazz Scale Studies. Pacific, Mo.: Mel Bay Publications. ISBN 978-078666708-6.
- "Accordion Anatomy". Western New York Accordion Club. See diagram "Bass Reed Switches". Retrieved 30 May 2015.