AKA: C diminished seventh, C°, Cdim, Cdim7, Cdim7th, Cdim/6, Cdim(add6)
Cdim7 Accordion Chord Chart
Green bass pattern: Cdim7(omit5) = Cm6(omit5)
Blue counter bass pattern: Cdim7
dim 7th Chords
A diminished 7th chords is a chord that consists of a root, a minor 3rd, a diminished 5th, and a diminished 7th. They can be formed by stacking minor 3rd intervals on top of each other. A minor 3rd interval is the distance between two notes that are three half steps apart, such as C and Eb. When you stack two minor 3rd intervals you get a diminished chord (triad), if you add another minor 3rd, you get a diminished 7th chord. It’s a chord that has regular intervals between each note.
Minor 3rd is a consonant interval but when you combine two minor 3rd intervals, you create an interval of 6 half steps from the root. This interval is known as a tritone and is a dissonant interval.
For example, if you start with the note C and stack two minor 3rd intervals on top of it (C-Eb-Gb), you will have formed a C diminished chord; adding another minor 3rd you get C-Eb-Gb-Bbb, which is C diminished 7th chord. This chord is typically represented by the abbreviation “dim7” or “o7”.
This chord has a very dissonant, unstable sound and is often used to create tension in music. It can be resolved by moving to a chord with a more stable sound, such as a major or minor chord.
A diminished seventh chord is equivalent to all four diminished seventh chords built on each of its notes. In other words, a diminished seventh chord can have any of its four notes as its root.
In this case:
Cdim7 = E♭dim7 = G♭dim7 = Adim7
(Please note that chord inversions do not work on the Stradella bass system like they do on other instruments or on the accordion keyboard itself. So although these equivalent chords have the exact same notes, they are not interchangeable and should not be intended as inversions of the same chord, at least for what concerns the left hand.)
dim 7th Chord Buttons
The diminished chord buttons on the accordion actually play diminished 7th chords without the 5th, this means that they play just the root, the minor 3rd, and the diminished 7th (which is a 6th). For this reason, diminished 7th chords on the Stradella bass system, can be seen also as minor 6th chords with no 5th.
C, E♭, G♭, B♭♭
(C, E♭, G♭, A)
Cdim button plays:
C, E♭, B♭♭ (no G♭)
R, m3°, dim5°, dim7°
Dim buttons play:
R, m3°, dim7° (no dim5°)
Green bass pattern:
Cdim7(omit5), same as Cm6(omit5)
C + Cdim
Blue counter bass pattern: Cdim7
C + G♭dim
(B# + F#dim)
4 + 2
sorry, there was a mistake, instead of B# there was a C# but as you can see, now it’s correct.
Thank you for pointing it out!
Hello! What happens if I combine C with Fdim ?
Very good site, thank you.
Fdim on the accordion is actually a Fdim7 without the 5th.
Diminished 7th chords structure is Root, minor 3rd, diminished 5th, and diminished 7th but on the accordion the 5th is omitted so we play just F(Root), Ab(minor 3rd), and D(diminished 7th, which is also the 6th).
Combining F, Ab, D (chord) + C (bass) you get a quite unusual C chord or some common chord inversions, in fact, you can see Fdim7 + C as:
– a Csus4b6(add9) aka Csus2/4(#5) because there’s the Root C, no 3rd (sus), the 4th F, the flat 6th (sharp 5th) Ab (G#) and the 9th (2nd) D
– an Fm6/C because Fdim7(5omit) is also an Fm6(5omit) which contains F, Ab, D and adding a C we complete the chord because C is the 5th of F.
– a Dm7b5/C because Dm7b5 contains D (root), F (minor 3rd), Ab (flat 5th), C (minor 7th)
Obviously, I suggest ignoring the C chord because it’s not a practical way to intend that chord.
So, reassuming Fdim7 + C = Fm6/C or Dm7b5/C
Thank you for your appreciation! 🙂
Now I understand, thank you very much for taking my doubts!
I wrote an instrumental song and did something that made me very confused LOL thanks!
You’re welcome 🙂