The 120 bass layout has 2 columns of single bass notes (roots and counter basses) and 4 columns of chords (Major, minor, Dominant 7th, and diminished 7th) in all keys. Compared to the smaller model (the 96 bass layout), it has 4 extra rows, for a total of 20 rows. Full size 120 bass accordions are the most flexible offering features not found on smaller instruments, this is why they are the most used accordions by professional accordionists.
If you are totally new to the Stradella bass system, read this article.
120 Bass Accordion Layout
(Click to enlarge)
All chords you can play on a 120 Bass Accordion
There are four columns of standard chords:
- 20 Major chords
- 20 Minor chords
- 20 Dominant 7th chords
- 20 Diminished 7th chords
in all keys. Combining chords and roots (or counter basses) you can get:
- 18 Dominant 7th flat 5th chords
- 18 Dominant 7th flat 9th chords
- 18 Dominant 11th chords
- 18 Dominant 9th sus4 chords
- 19 Dominant 9th chords
- 19 Major 7th/9th chords
- 19 minor(Major 9th) chords
- 19 minor 9th chords
- 20 minor 7th chords
- 20 Half-diminished chords
- 20 Diminished triad chords
- 24 Major 6th chords
- 24 Major 7th chords
When a chord family has more than 12 chords it means that the extra ones are duplicates found in different positions on the button board.
How to read the lists of chords
Here are some guidelines to help you read the following lists of chords and charts:
- Flats and sharps are paired with their enharmonic equivalent chord, for example, C#Maj7 = DbMaj7
- Chords that can be played are clickable and are colored in dark red, for example, DMaj
- Chords that can’t be played are colored in gray and are crossed out by a horizontal line, for example,
Bdim7. - Duplicated chords are colored in light blue, for example, E#m7 = Fm7
- Some chords can be played in two different ways:
-
- by combining a chord with a bass note or
- by combining a chord with a counter-bass button.
The charts of those extended chords that can be built combining a chord with a counter bass or with a bass note, show both positions: counter basses are circled in blue, and basses are circled in green.
Usually, the green pattern is the most common and convenient. However, in some cases, it could be easier to play the root on the counter bass column.
For this reason, you’ll find two lists for the same group of chords, one for those that can be played combining a counter bass with a chord (“On Counter Bass” list) and one for those chords that can be played combining a bass note (“On Root” list).
Standard chords
20 Major chords
Major chords are built with a Root (R), a major third (3rd), and a perfect fifth (5th).
On a 120 bass accordion you can play these Major chords:
- A#Maj = BbMaj
- D#Maj = EbMaj
- G#Maj = AbMaj
- C#Maj = DbMaj
- F#Maj = GbMaj
- BMaj
- EMaj
- AMaj
- DMaj
- GMaj
- CMaj
- FMaj
- BbMaj = A#Maj
- EbMaj = D#Maj
- AbMaj = G#Maj
- DbMaj = C#Maj
- GbMaj = F#Maj
- CbMaj = BMaj
- FbMaj = EMaj
- BbbMaj = AMaj
20 Minor chords
Minor chords are built with a Root (R), a minor third (m3rd), and a perfect fifth (5th).
On a 120 bass accordion you can play these minor chords:
- A#m = Bbm
- D#m = Ebm
- G#m = Abm
- C#m = Dbm
- F#m = Gbm
- Bm
- Em
- Am
- Dm
- Gm
- Cm
- Fm
- Bbm = A#m
- Ebm = D#m
- Abm = G#m
- Dbm = C#m
- Gbm = F#m
- Cbm = Bm
- Fbm = Em
- Bbbm = Am
20 Dominant 7th (5th omitted) chords
Dominant 7th chords are Major chords with a minor 7th added.
Dominant 7th chords are built with a Root (R), a major third (3rd), a perfect fifth (5th) and a minor seventh (m7th).
The 7th chord buttons on the Stradella bass system play just the root, the 3rd, and the 7th. The 5th is omitted.
On a 120 bass accordion you can play these Dominant 7th chords:
- A#7 = Bb7
- D#7 = Eb7
- G#7 = Ab7
- C#7 = Db7
- F#7 = Gb7
- B7
- E7
- A7
- D7
- G7
- C7
- F7
- Bb7 = A#7
- Eb7 = D#7
- Ab7 = G#7
- Db7 = C#7
- Gb7 = F#7
- Cb7 = B7
- Fb7 = E7
- Bbb7 = A7
20 Diminished 7th (5th omitted) chords
Diminished 7th chords are minor chords with a diminished 5th and a diminished 7th added.
They are built with a Root (R), a minor third (3rd), a diminished fifth (d5th), and a diminished 7th (d7th).
On the Stradella system, Diminished chord buttons play a diminished 7th instead of a diminished 5th, which is omitted.
On a 120 bass accordion you can play these Diminished 7th (5th omitted) chords:
- A#dim7 = Bbdim7
- D#dim7 = Ebdim7
- G#dim7 = Abdim7
- C#dim7 = Dbdim7
- F#dim7 = Gbdim7
- Bdim7
- Edim7
- Adim7
- Ddim7
- Gdim7
- Cdim7
- Fdim7
- Bbdim7
- Ebdim7
- Abdim7 = G#dim7
- Dbdim7 = C#dim7
- Gbdim7 = F#dim7
- Cbdim7 = Bdim7
- Fbdim7 = Edim7
- Bbbdim7 = Adim7
same as
20 minor 6th (5th omitted) chords
Minor 6th chords are minor chords with a major 6th added.
They are built with a Root (R), a minor third (3rd), a perfect fifth (5th), and a major sixth (6th).
On the Stradella bass system, diminished 7th chords are also minor 6th chords because there’s no diminished 5th and a 6th interval is equal to a diminished 7th interval. Minor 6th chords and diminished 7th chords can be thought of as equivalent in the Stradella bass system.
On a 120 bass accordion you can play these minor 6th chords:
- A#m6 = Bbm6
- D#m6 = Ebm6
- G#m6 = Abm6
- C#m6 = Dbm6
- F#m6 = Gbm
- Bm6
- Em6
- Am6
- Dm6
- Gm6
- Cm6
- Fm6
- Bbm6
- Ebm6
- Abm6 = G#m6
- Dbm6 = C#m6
- Gbm6 = F#m6
- Cbm6 = Bm6
- Fbm6 = Em6
- Bbbm6 = Am6
Combined Chords
18 Dominant 7th flat 5th chords
The Dominant 7th flat 5th chord (7b5) is a Dominant 7th chord with a flat 5th added.
It is built with a Root (R), a major third (3rd), a diminished fifth (d5th), and a minor seventh (m7th).
On the accordion, you can play a 7b5 chord by combining a Root with the Dominant 7th chord built on its flat 5th interval, for example, C + Gb7 = C7b5. C is the Root and Gb is the flat 5th of C.
On a 120 bass accordion you can play these Dominant 7th flat 5th chords:
On Counter Bass:
- Cx7b5 = D7b5
- Fx7b5 = G7b5
- B#7b5 = C7b5
- E#7b5 = F7b5
- A#7b5 = Bb7b5
- D#7b5 = Eb7b5
- G#7b5 = Ab7b5
- C#7b5 = Db7b5
- F#7b5 = Gb7b5
- B7b5
- E7b5
- A7b5
- D7b5
- G7b5
- C7b5
- F7b5
- Bb7b5 = A#7b5
- Eb7b5 = D#7b5
On Root:
- A#7b5 = Bb7b5
- D#7b5 = Eb7b5
- G#7b5 = Ab7b5
- C#7b5 = Db7b5
- F#7b5 = Gb7b5
- B7b5
- E7b5
- A7b5
- D7b5
- G7b5
- C7b5
- F7b5
- Bb7b5 = A#7b5
- Eb7b5 = D#7b5
18 Dominant 7th flat 9th chords
The Dominant 7th flat 9th chord (7b9) is a dominant 7th chord with a minor 9th (same as a minor 2nd) added.
It is built with a Root (R), a major third (3rd), a perfect fifth (5th), a minor 7th ( m7th), and a minor ninth (m9th).
On the accordion, you can play a 7b9 chord by combining a Root and its major chord with the diminished chord built on its minor 7th interval, for example, C + CMaj + Bbdim = C7b9.
On a 120 bass accordion you can play these Dominant 7th flat 9th chords:
- A#7b9 = Bb7b9
- D#7b9 = Eb7b9
- G#7b9 = Ab7b9
- C#7b9 = Db7b9
- F#7b9 = Gb7b9
- B7b9
- E7b9
- A7b9
- D7b9
- G7b9
- C7b9
- F7b9
- Bb7b9 = A#7b9
- Eb7b9 = D#7b9
- Ab7b9 = G#7b9
- Db7b9 = C#7b9
- Gb7b9 = F#7b9
- Cb7b9 = B7b9
18 Dominant 11th chords
The Dominant 11th chord is a dominant 7th chord with a major 9th (same as a 2nd) and an 11th (same as a 4th) added.
It is built with a Root (R), a major third (3rd), a perfect fifth (5th), a minor 7th (m7th), a major ninth (9th), and an eleventh (11th).
On the accordion, you can play a Dominant 11th chord by combining a Root and its major chord with the major chord built on its minor 7th interval, for example, C + CMaj + BbMaj = C11.
The 11th interval is dissonant in major and dominant chords because the 11th and the major 3rd are adjacent tones.
For example, C11 = C, E, G, Bb, D, F.
On a 120 bass accordion you can play these Dominant 11th chords:
- A#11 = Bb11
- D#11 = Eb11
- G#11 = Ab11
- C#11 = Db11
- F#11 = Gb11
- B11
- E11
- A11
- D11
- G11
- C11
- F11
- Bb11 = A#11
- Eb11 = D#11
- Ab11 = G#11
- Db11 = C#11
- Gb11 = F#11
- Cb11 = B11
18 Dominant 9th sus4 chords
Dominant seventh ninth suspended chords (9sus4) consist of a Root (R), no third, a perfect fourth (4th), no fifth, a minor seventh (m7th), and a ninth (9th) note of the major scale built on the root.
Stradella bass system allows you to play 9sus4 chords on the accordion combining the root bass with the major chord of its minor 7th degree, for example, C + BbMaj = C9sus4
On a 120 bass accordion you can play these Dominant 9th sus4 chords:
- A#9sus4 = Bb9sus4
- D#9sus4 = Eb9sus4
- G#9sus4 = Ab9sus4
- C#9sus4 = Db9sus4
- F#9sus4 = Gb9sus4
- B9sus4
- E9sus4
- A9sus4
- D9sus4
- G9sus4
- C9sus4
- F9sus4
- Bb9sus4 = A#9sus4
- Eb9sus4 = D#9sus4
- Ab9sus4 = G#9sus4
- Db9sus4 = C#9sus4
- Gb9sus4 = F#9sus4
- Cb9sus4 = B9sus4
19 Dominant 9th chords
A Dominant 9th chord is a Dominant 7th chord with a Major 9th added.
It is built with a Root (R), a major third (3rd), a perfect fifth (5th), a minor seventh (m7th), and a major ninth (9th).
On the Stradella bass system, you can play a Dominant 9th chord by combining a Root and its major chord with the minor chord built on its 5th interval, for example, C + CMaj + Gm = C9.
On a 120 bass accordion you can play these Dominant 9th chords:
- D#9 = Eb9
- G#9 = Ab9
- C#9 = Db9
- F#9 = Gb9
- B9
- E9
- A9
- D9
- G9
- C9
- F9
- Bb9 = A#9
- Eb9 = D#9
- Ab9 = G#9
- Db9 = C#9
- Gb9 = F#9
- Cb9 = B9
- Fb9 = E9
- Bbb9 = A9
19 Major 7th/9th chords
The Major 7th/9th chord (Maj7/9) is a Major 7th chord with a major 9th added.
It is built with a Root (R), a major third (3rd), a perfect fifth (5th), a major seventh (7th), and a major ninth (9th).
On the accordion, you can play a Major 7th/9th chord by combining a Root and its Major chord with the Major chord built on the 5th interval from the Root, for example, C + CMaj + GMaj = CMaj7/9.
On a 120 bass accordion you can play these Major 7th/9th chords:
- D#Maj7/9 = EbMaj7/9
- G#Maj7/9 = AbMaj7/9
- C#Maj7/9 = DbMaj7/9
- F#Maj7/9 = GbMaj7/9
- BMaj7/9
- EMaj7/9
- AMaj7/9
- DMaj7/9
- GMaj7/9
- CMaj7/9
- FMaj7/9
- BbMaj7/9 = A#Maj7/9
- EbMaj7/9 = D#Maj7/9
- AbMaj7/9 = G#Maj7/9
- DbMaj7/9 = C#Maj7/9
- GbMaj7/9 = F#Maj7/9
- CbMaj7/9 = BMaj7/9
- FbMaj7/9 = EMaj7/9
- BbbMaj7/9 = AMaj7/9
19 minor(Major 9th) chords
The minor(Major 9th) chord is a minor 7th chord with a major 9th added.
It is built with a Root (R), a minor third (m3rd), a perfect fifth (5th), a major seventh (7th), and a major ninth (9th).
On the accordion, you can play a minor(Major 9th) chord by combining a Root and its minor chord with the Major chord built on its 5th interval, for example, C + Cmin + GMaj = Cm(Maj9)
On a 120 bass accordion you can play these minor(Maj9) chords:
- D#m(Maj9) = Ebm(Maj9)
- G#m(Maj9) = Abm(Maj9)
- C#m(Maj9) = Dbm(Maj9)
- F#m(Maj9) = Gbm(Maj9)
- Bm(Maj9)
- Em(Maj9)
- Am(Maj9)
- Dm(Maj9)
- Gm(Maj9)
- Cm(Maj9)
- Fm(Maj9)
- Bbm(Maj9) = A#m(Maj9)
- Ebm(Maj9) = D#m(Maj9)
- Abm(Maj9) = G#m(Maj9)
- Dbm(Maj9) = C#m(Maj9)
- Gbm(Maj9) = F#m(Maj9)
- Cbm(Maj9) = Bm(Maj9)
- Fbm(Maj9) = Em(Maj9)
- Bbbm(Maj9) = Am(Maj9)
19 minor 9th chords
A minor 9th chord is a minor chord with a minor 7th and a major 9th added.
It is built with a Root (R), a minor third (m3rd), a perfect fifth (5th), a minor seventh (m7th), and a major ninth (9th).
On the Stradella bass system, you can play a minor 9th chord by combining a Root and its minor chord with the minor chord built on the 5th interval, for example, C + Cm + Gm = Cm9.
On a 120 bass accordion you can play these minor 9th chords:
- D#m9 = Ebm9
- G#m9 = Abm9
- C#m9 = Dbm9
- F#m9 = Gbm9
- Bm9
- Em9
- Am9
- Dm9
- Gm9
- Cm9
- Fm9
- Bbm9 = A#m9
- Ebm9 = D#m9
- Abm9 = G#m9
- Dbm9 = C#m9
- Gbm9 = F#m9
- Cbm9 = Bm9
- Fbm9 = Em9
- Bbbm9 = Am9
20 minor 7th chords
A minor 7th chord is a minor chord with a minor 7th added.
It is built with a Root (R), a minor third (m3rd), a perfect fifth (5th), and a minor seventh (m7th).
On the Stradella bass system, you can play a minor 7th chord by combining a Root with the Major chord built on its minor 3rd interval, for example, C + EbMaj = Cm7.
On a 120 bass accordion you can play these minor 7th chords:
On Counter Bass:
- Fxm7 = Gm7
- B#m7 = Cm7
- E#m7 = Fm7
- A#m7 = Bbm7
- D#m7 = Ebm7
- G#m7 = Abm7
- C#m7 = Dbm7
- F#m7 = Gbm7
- Bm7
- Em7
- Am7
- Dm7
- Gm7
- Cm7
- Fm7
- Bbm7 = A#m7
- Ebm7 = D#m7
- Abm7 = G#m7
- Dbm7 = C#m7
On Root:
- A#m7 = Bbm7
- D#m7 = Ebm7
- G#m7 = Abm7
- C#m7 = Dbm7
- F#m7 = Gbm7
- Bm7
- Em7
- Am7
- Dm7
- Gm7
- Cm7
- Fm7
- Bbm7 = A#m7
- Ebm7 = D#m7
- Abm7 = G#m7
- Dbm7 = C#m7
- Cbm7 = Bm7
20 Half-diminished chords
The minor 7th flat 5th chord (half-diminished) is a minor chord with a flat 5th and a minor 7th added.
It is built with a Root (R), a minor third (m3rd), a diminished fifth (d5th), and a minor seventh (m7th).
On the accordion, you can play a Half-diminished chord by combining a Root with the minor chord built on its minor 3rd interval, for example, C + Ebm = Cm7b5.
On a 120 bass accordion you can play these minor 7th flat 5th chords:
On Counter Bass:
- Fxm7b5 = Gm7b5
- B#m7b5 = Cm7b5
- E#m7b5 = Fm7b5
- A#m7b5 = Bbm7b5
- D#m7b5 = Ebm7b5
- G#m7b5 = Abm7b5
- C#m7b5 = Dbm7b5
- F#m7b5 = Gbm7b5
- Bm7b5
- Em7b5
- Am7b5
- Dm7b5
- Gm7b5
- Cm7b5
- Fm7b5
- Bbm7b5 = A#m7b5
- Ebm7b5 = D#m7b5
- Abm7b5 = G#m7b5
- Dbm7b5 = C#m7b5
On Root:
- A#m7b5 = Bbm7b5
- D#m7b5 = Ebm7b5
- G#m7b5 = Abm7b5
- C#m7b5 = Dbm7b5
- F#m7b5 = Gbm7b5
- Bm7b5
- Em7b5
- Am7b5
- Dm7b5
- Gm7b5
- Cm7b5
- Fm7b5
- Bbm7b5 = A#m7b5
- Ebm7b5 = D#m7b5
- Abm7b5 = G#m7b5
- Dbm7b5 = C#m7b5
- Gbm7b5 = F#m7b5
20 Diminished triad chords
Diminished triad chords are a type of musical chord consisting of three notes: the root note, a minor 3rd above the root, and a diminished 5th above the root.
On a standard bass accordion you have to combine a root and the dim7 chord built on its minor 3rd to get a diminished triad. In most of the cases it’s more practical and easy to play a dim7 chord in place of a diminished triad.
On a 120 bass accordion you can play these diminished triad chords:
On Counter Bass:
- Fxdim = Gdim
- B#dim = Cdim
- E#dim = Fdim
- A#dim = Bbdim
- D#dim = Ebdim
- G#dim = Abdim
- C#dim = Dbdim
- F#dim = Gbdim
- Bdim
- Edim
- Adim
- Ddim
- Gdim
- Cdim
- Fdim
- Bbdim = A#dim
- Ebdim = D#dim
- Abdim = G#dim
- Dbdim = C#dim
On Root:
- A#dim = Bbdim
- D#dim = Ebdim
- G#dim = Abdim
- C#dim = Dbdim
- F#dim = Gbdim
- Bdim
- Edim
- Adim
- Ddim
- Gdim
- Cdim
- Fdim
- Bbdim = A#dim
- Ebdim = D#dim
- Abdim = G#dim
- Dbdim = C#dim
- Gbdim = F#dim
24 Major 6th chords
The Major 6th chord is a Major chord with a major 6th added.
It is built with a Root (R), a major third (3rd), a perfect fifth (5th), and a major sixth (6th).
On the accordion, you can play a Major 6th chord by combining a Root with the minor chord built on its 6th interval, for example, C + Am = C6.
On a 120 bass accordion you can play these Major 6th chords:
On Counter Bass:
- Cx6 = D6
- Fx6 = G6
- B#6 = C6
- E#6 = F6
- A#6 = Bb6
- D#6 = Eb6
- G#6 = Ab6
- C#6 = Db6
- F#6 = Gb6
- B6
- E6
- A6
- D6
- G6
- C6
On Root:
- C#6 = Db6
- F#6 = Gb6
- B6
- E6
- A6
- D6
- G6
- C6
- F6
- Bb6 = A#6
- Eb6 = D#6
- Ab6 = G#6
- Db6 = C#6
- Gb6 = F#6
- Cb6 = B6
- Fb6 = E6
- Bbb6 = A6
24 Major 7th chords
The Major 7th chord is a Major chord with a major 7th added.
It is built with a Root (R), a major third (3rd), a perfect fifth (5th), and a major seventh (7th).
On the accordion, you can play a Major 7th chord by combining a Root with the minor chord built on its 3rd interval, for example, C + Em = CMaj7.
On a 120 bass accordion you can play these Major 7th chords:
On Counter Bass:
- CxMaj7 = DMaj7
- FxMaj7 = GMaj7
- B#Maj7 = CMaj7
- E#Maj7 = FMaj7
- A#Maj7 = BbMaj7
- D#Maj7 = EbMaj7
- G#Maj7 = AbMaj7
- C#Maj7 = DbMaj7
- F#Maj7 = GbMaj7
- BMaj7
- EMaj7
- AMaj7
- DMaj7
- GMaj7
- CMaj7
- FMaj7
On Root:
- F#Maj7 = GbMaj7
- BMaj7
- EMaj7
- AMaj7
- DMaj7
- GMaj7
- CMaj7
- FMaj7
- BbMaj7 = A#Maj7
- EbMaj7 = D#Maj7
- AbMaj7 = G#Maj7
- DbMaj7 = C#Maj7
- GbMaj7 = F#Maj7
- CbMaj7 = BMaj7
- FbMaj7 = EMaj7
- BbbMaj7 = AMaj7