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40 Bass Accordion Chart

    The 40 bass layout has 2 columns of single bass notes (roots and counter basses), 3 columns of chords (Major, minor, Dominant 7th), and 8 rows.

    Compared to the smaller model (the 32 bass layout), it has the same number of bass keys but it can also play Dominant 7th chords and it has an extra counter basses column. The 4 missing keys are (F#/Gb), B, (Ab/G#), (Db/C#).

    It doesn’t have diminished chord buttons, but it may still be able to play diminished chords if the 7th chord buttons are omitting the Root:

    Some 40, 60 and 80 bass accordions play a different triad on the 7th chord bass buttons: instead of playing the Root, the 3rd, and the 7th omitting the 5th, they play the 3rd the 5th, and the 7th omitting the Root. This notes arrangement derives from the 3 +3 French bass system (3 columns of bass notes: minor 3rd, major 3rd, and Roots and 3 columns of chords: Major, minor, and 7th).

    This is a very clever layout that allows you to play both 7th chords and diminished chords on accordions with just three columns of chords. As a matter of fact, the 3rd, the 5th, and the 7th notes of a 7th chord also form a diminished triad that can be combined with a bass note to form a diminished chord.

    Diminished chords on the French layout

    Despite the lack of diminished chord buttons, you can play them by combining a Root with the 7th chord of its 4th interval (which is found just below the Root line). For example, F7 plays these notes: A, C, Eb
    Playing C + F7 you get a Cdim7(5th omitted) because A became the diminished 7th, C doubles the root, and Eb is the minor 3rd.

    Dominant 7th chords on the French layout

    On these models of accordion, the 7th chords are complete since you can play the Root on the bass column and the 3rd, the 5th, the 7th by pushing the 7th chord button.

    Combined chords on the French layout

    If your 7th chord buttons play the 3rd, the 5th, and the 7th, all combinations of chords presented here are still valid with the exception of 7b5 and 7b9 chords.

    The combination illustrated here for playing a 7b5 chord on a standard Stradella bass system will produce a 7b9 chord on a French system accordion.

     

    If you are totally new to the Stradella bass system, read this article.


    40 Bass Accordion Layout

    40 bass accordion chart layout
    On the left, you can see a 40 bass layout, overlaid with a 120 bass layout. The chart on the right shows you which notes are played by each button.


    All chords you can play on a 40 Bass Accordion

    There are three columns of standard chords:

    • 8 major chords
    • 8 minor chords
    • 8 dominant 7th chords

    in the keys of E, A, D, G, C, F, Bb, and Eb, however, combining chords and roots (or counter basses) you can get:

    • 6 Dominant 11th chords
    • 6 Dominant 9th sus4 chords
    • 6 Dominant 7th flat 5th chords
    • 7 Dominant 9th chords
    • 7 Major 7th/9th chords
    • 7 minor(Major 9th) chords
    • 7 minor 9th chords
    • 8 Major 6th chords
    • 8 Major 7th chords
    • 8 minor 7th chords
    • 8 Half-diminished chords


    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:
      1. by combining a chord with a bass note or
      2. by combining a chord with a counter-bass button.
    Cm7b5 chord position
    You can play the root on the bass row or on the counter bass.

    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

    8 Major chords

    Major chords are built with a Root (R), a major third (3rd), and a perfect fifth (5th).

     

    On a 40 bass accordion you can play these Major chords:

     

    • F#Maj = GbMaj
    • BMaj              
    • EMaj              
    • AMaj              
    • DMaj              
    • GMaj              
    • CMaj              
    • FMaj              
    • BbMaj = A#Maj
    • EbMaj = D#Maj
    • AbMaj = G#Maj 
    • DbMaj = C#Maj 


    8 Minor chords

    Minor chords are built with a Root (R), a minor third (m3rd), and a perfect fifth (5th).

     

    On a 40 bass accordion you can play these minor chords:

     

    • F#m = Gbm 
    • Bm            
    • Em            
    • Am            
    • Dm            
    • Gm            
    • Cm            
    • Fm           
    • Bbm = A#m 
    • Ebm = D#m
    • Abm = G#m
    • Dbm = C#m 

     


    8 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 usually play just the Root, the 3rd, and the 7th. The 5th is omitted.

    *NOTE: In case the 7th chord buttons are omitting the Root instead of the 5th (French layout), you can get full 7th chords by playing a bass Root and its 7th chord which contains the 3rd, the 5th, and the 7th.

     

    On a 40 bass accordion you can play these Dominant 7th chords:

     

    • F#7 = Gb7
    • B7         
    • E7         
    • A7         
    • D7         
    • G7         
    • C7         
    • F7         
    • Bb7 = A#7
    • Eb7 = D#7
    • Ab7 = G#7
    • Db7 = C#7 



    Combined Chords

    6 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 40 bass accordion you can play these Dominant 11th chords:

     

    • F#11 = Gb11
    • B11               
    • E11               
    • A11               
    • D11               
    • G11               
    • C11               
    • F11               
    • Bb11 = A#11 
    • Eb11 = D#11
    • Ab11 = G#11 
    • Db11 = C#11 

     


    6 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 40 bass accordion you can play these Dominant 9th sus4 chords:

     

    • F#9sus4 = Gb9sus4 
    • B9sus4                  
    • E9sus4                  
    • A9sus4                  
    • D9sus4                  
    • G9sus4                  
    • C9sus4                  
    • F9sus4                  
    • Bb9sus4 = A#9sus4 
    • Eb9sus4 = D#9sus4 
    • Ab9sus4 = G#9sus4 
    • Db9sus4 = C#9sus4 


    6 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.

    *NOTE: In case the 7th chord buttons are omitting the Root instead of the 5th (French layout), you can’t play 7b5 chords as shown in these charts.

     

    On a 40 bass accordion you can play these Dominant 7th flat 5th chords:

     

    On Counter Bass:

    • G#7b5 = Ab7b5
    • C#7b5 = Db7b5
    • F#7b5 = Gb7b5
    • B7b5             
    • E7b5             
    • A7b5             
    • D7b5              
    • G7b5              
    • C7b5              
    • F7b5              
    • Bb7b5 = A#7b5 
    • Eb7b5 = D#7b5 

     

    On Root:

    • F#7b5 = Gb7b5
    • B7b5             
    • E7b5             
    • A7b5             
    • D7b5             
    • G7b5             
    • C7b5             
    • F7b5             
    • Bb7b5 = A#7b5
    • Eb7b5 = D#7b5
    • Ab7b5 = G#7b5
    • Db7b5 = C#7b5 


    7 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 40 bass accordion you can play these Dominant 9th chords:

     

    • F#9 = Gb9
    • B9          
    • E9          
    • A9          
    • D9          
    • G9          
    • C9          
    • F9          
    • Bb9 = A#9 
    • Eb9 = D#9 
    • Ab9 = G#9 
    • Db9 = C#9  

     


    7 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 40 bass accordion you can play these Major 7th/9th chords:

     

    • 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   


    7 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 40 bass accordion you can play these minor(Maj9) chords:

     

    • 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) 

     


    7 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 40 bass accordion you can play these minor 9th chords:

     

    • F#m9 = Gbm9
    • Bm9             
    • Em9             
    • Am9             
    • Dm9             
    • Gm9             
    • Cm9             
    • Fm9             
    • Bbm9 = A#m9 
    • Ebm9 = D#m9 
    • Abm9 = G#m9
    • Dbm9 = C#m9 


    8 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 40 bass accordion you can play these Major 6th chords:

     

    On Counter Bass:

    • G#6 = Ab6
    • C#6 = Db6
    • F#6 = Gb6
    • B6         
    • E6         
    • A6         
    • D6         
    • G6         
    • C6         
    • F6         
    • Bb6 = A#6
    • Eb6 = D#6

     

    On Root:

    • F#6 = Gb6
    • B6          
    • E6          
    • A6          
    • D6          
    • G6          
    • C6          
    • F6          
    • Bb6 = A#6 
    • Eb6 = D#6 
    • Ab6 = G#6 
    • Db6 = C#6 


    8 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 40 bass accordion you can play these Major 7th chords:

     

    On Counter Bass:

    • G#Maj7 = AbMaj7
    • C#Maj7 = DbMaj7
    • F#Maj7 = GbMaj7
    • BMaj7                
    • EMaj7                
    • AMaj7                
    • DMaj7                
    • GMaj7                
    • CMaj7                
    • FMaj7                
    • BbMaj7 = A#Maj7
    • EbMaj7 = D#Maj7

     

    On Root:

    • EMaj7                
    • AMaj7                
    • DMaj7                
    • GMaj7                
    • CMaj7                
    • FMaj7                
    • BbMaj7 = A#Maj7
    • EbMaj7 = D#Maj7
    • AbMaj7 = G#Maj7
    • DbMaj7 = C#Maj7 
    • GbMaj7 = F#Maj7 
    • CbMaj7 = BMaj7   


    8 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 40 bass accordion you can play these minor 7th chords:

     

    On Counter Bass:

    • C#m7 = Dbm7
    • F#m7 = Gbm7
    • Bm7             
    • Em7             
    • Am7             
    • Dm7             
    • Gm7             
    • Cm7             
    • Fm7             
    • Bbm7 = A#m7 
    • Ebm7 = D#m7 
    • Abm7 = G#m7 

     

    On Root:

    • F#m7 = Gbm7
    • Bm7             
    • Em7             
    • Am7             
    • Dm7             
    • Gm7             
    • Cm7             
    • Fm7             
    • Bbm7 = A#m7
    • Ebm7 = D#m7
    • Abm7 = G#m7
    • Dbm7 = C#m7 


    8 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 40 bass accordion you can play these minor 7th flat 5th chords:

     

    On Counter Bass:

    • C#m7b5 = Dbm7b5 
    • F#m7b5 = Gbm7b5 
    • Bm7b5                  
    • Em7b5                  
    • Am7b5                  
    • Dm7b5                  
    • Gm7b5                  
    • Cm7b5                  
    • Fm7b5                  
    • Bbm7b5 = A#m7b5 
    • Ebm7b5 = D#m7b5 
    • Abm7b5 = G#m7b5 

     

    On Root:

    • F#m7b5 = Gbm7b5
    • Bm7b5                 
    • Em7b5                 
    • Am7b5                 
    • Dm7b5                 
    • Gm7b5                 
    • Cm7b5                 
    • Fm7b5                  
    • Bbm7b5 = A#m7b5  
    • Ebm7b5 = D#m7b5  
    • Abm7b5 = G#m7b5  
    • Dbm7b5 = C#m7b5   

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    Comments:

    1. With time to your satisfaction
      You have created a page with good and excellent and in-depth technical music information.
      Accept my congratulations from afar.
      You have written well about chords and their ratios. Understanding and using them requires practical creativity from these mathematical-poetry sounds.
      I wish you inner happiness.
      an elderly musician; Poor but happy from Iran

      1. I am truly grateful for your kind and thoughtful message.
        Your words of appreciation mean a lot to me, and it’s incredibly heartwarming to receive such positive feedback.
        I cannot thank you enough for taking the time to share your kind words.

        Thank you so much!

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