I'm fairly new to the accordion and have played piano in the past. I mostly play by ear and just trying things out. I have a 120 bass piano accordion.

When I play the chord buttons, I don't use the diminished chords row, because I don't know an easy reason for using them. In other words, while I can see that I can create a minor seventh chord using the major chord button with the sixth in the bass, I can't see an obvious similar fancy chord using the diminished row. It seems like it would only be useful for the occasional alternate 7th chord, as I already have a row for 7ths.

Please could someone help me understand some good bass button combinations using the diminished row, or something to practice using that row which would help me incorporate it more naturally into my playing.

  • What -- the viola was too mainstream for you? (hey, folks, this is a meta-joke , m'kay?) – Carl Witthoft Oct 14 '15 at 13:36

You can play X7b9 or X7b9b13 chords.

Let's take D7b9, for example. You take the D bass from the major third bass row and play Eb dim chord from the diminished row. As a result you get D bass + Eb-Gb-C chord. In a similar way, you play D7b9b13 when you press the same D bass + Eb minor from the minor chords row + Eb dim and you get D + Eb-Gb-Bb-C.

A good book, containing a table with more than 40 chord combinations + theory and exercises is: "Accordion Jazz Chords, Free improvising on the stradella bass accordion" by Norbert Seidel (ISBN 3-925572-09-0). I think it can give a lot of inspiration for unleashing the freedom with the left hand.


While the diminuished chord leaves out the fifth to the fundamental, the minor third and diminuished seventh also combine into a minor fifth.

So the diminuished row is mostly useful for chords already containing a diminuished fifth (like the dominant seventh between seventh and major third). So the number of chords where it comes in handy is limited.

It's a nice voicing for the seventh in an alternating bass scheme (and the reason five-row standard bass only contains the diminuished chords but in the position of the seventh). It's also obviously useful for, well, diminuished chords. And it combines straightforwardly with the corresponding minor chord to Cm6 (for example) exactly because of its missing fifth.

But that's mostly it for straightforward uses of the row. Most other combinations are either fairly esoteric or cavalier about adding additional notes into the result.


I have played accordion for (too) many years and my main use of the diminished chord buttons was to play a diminished chord. The Stradella bass arrangement drops the fifth out of both the dominant seventh and diminished seventh chords. This gives some flexibility (and balances the sound of 4-note vs 3-note chords) in playing less common chords. (The dominant 7th is actually an Italian Sixth and can also be used to make French Sixths or German Sixths which themselves are just dominant sevenths on another root.)

Often one can substitute the vii0 chord for a V7 chord. So the diminished seventh in the "D" bass line can be used in place of a G7 chord; the D diminished 7th missing the fifth is just FBD, a G7 missing the root or an B diminished. The full diminished seventh consists of 3 stacked minor thirds and any one could be the root.

Note: there are some accordions that have full dominant and diminished sevenths chords, at least so I have read.


Minor sixth chords are delicious and common in a lot of minor folk musics (and Latin music & swing).

Cm6 is C Eb G A. Since the diminished chord buttons drop the 5, you can get that by pressing the minor (C Eb G) and the diminished (A C Eb) button at the same time.


The simplest explanation for the use of the diminished row, in terms of both layout and harmonic function, is as the diatonic "ii dim" in minor keys. As such, it is placed in the "subdominant" row, relative to the tonic. You can see and hear this relationship by comparing the major-key progression I-IV-V7-I (C-F-G7-C in C major) with the minor-key progression i-iidim-V7-i (cm-ddim-G7-cm in c minor).

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