Learn › A Flat Half-Diminished Chord on Piano (Abm7b5)
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A Flat Half-Diminished Chord on Piano (Abm7b5)
The A flat half-diminished 7th chord (Abm7b5) on the piano has four notes: Ab, Cb, Ebb, Gb. It is an Abdim triad with a minor seventh, Gb, on top. Formula 1 b3 b5 b7. Learn the shape and the inversions, then practise Abm7b5 by playing.
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- MIDI keyboard
- Digital or acoustic piano
- Guitar
- Computer, phone or tablet
What Abm7b5 does in music
- Abm7b5 is the iiø7 of F# minor (as G#m7b5) and the viiø7 of A major (as G#m7b5).
- In a minor ii-V-i it opens the cadence: Abm7b5 (G#m7b5) → C#7 → F#m.
- Abm7b5 has the same notes as Cbm6 (Cb Ebb Gb Ab): with Ab in the bass it is Abm7b5, with Cb in the bass it is Cbm6.
Four ways to play Abm7b5
In the 3rd inversion Gb is the lowest note: the seventh in the bass.
Root position: Ab Cb Ebb Gb
1st inversion: Cb Ebb Gb Ab
2nd inversion: Ebb Gb Ab Cb
3rd inversion: Gb Ab Cb Ebb
A 5-minute Abm7b5 routine
- Play Ab, Cb, Ebb, Gb slowly in root position and say "Abm7b5" each time.
- Walk up through the inversions (Cb Ebb Gb Ab, Ebb Gb Ab Cb, Gb Ab Cb Ebb) without lifting the whole hand.
- Loop Abm7b5 (G#m7b5) → C#7 → F#m until the change into and out of Abm7b5 is clean.
- Finally meet it in random order between other chords, with a check on every note.
A few minutes every day on Abm7b5 beat one long session a week.
Abm7b5 compared with the other 7th chords on Ab
Same root, same fifth: watch the third and the seventh.
Playing Abm7b5 with each hand
| Hand | Ab | Cb | Ebb | Gb |
|---|---|---|---|---|
| Right hand | 1 (thumb) | 2 | 3 | 5 (little) |
| Left hand | 5 (little) | 3 | 2 | 1 (thumb) |
Too much stretch? Play Ab alone in the left hand and Cb Ebb Gb in the right.
Abm7b5 without the third
Here keep the flat fifth: Ab Ebb Gb, root, b5 and seventh. The b5 is what separates Abm7b5 from Abm7, so the third is the note to leave out.
Practise Abm7b5 by playing
Knowing Abm7b5 on paper is step one. ChordRunner makes you find it fast, mixed with other chords. MIDI keyboard or microphone, both work.
Play the demoCommon questions
What is the difference between Abm7b5 and Abdim?
Abm7b5 adds one note to the Abdim triad: Gb, the minor seventh. That fourth note is what makes it a seventh chord.
What are the inversions of Abm7b5?
Root position Ab Cb Ebb Gb, 1st inversion Cb Ebb Gb Ab, 2nd inversion Ebb Gb Ab Cb and 3rd inversion Gb Ab Cb Ebb. Every position is still Abm7b5.
Where does Abm7b5 go?
Abm7b5 is the iiø7 of F# minor (as G#m7b5) and the viiø7 of A major (as G#m7b5). In a minor ii-V-i it opens the cadence: Abm7b5 (G#m7b5) → C#7 → F#m.
Can I practise Abm7b5 with a MIDI keyboard?
Yes. In ChordRunner a USB MIDI keyboard is detected automatically, and an acoustic piano works through the microphone. Abm7b5 counts in any inversion, as long as Ab, Cb, Ebb, Gb sound together.
Your instrument is the controller.
ChordRunner is a browser game that teaches piano and guitar chords: a chord appears on screen, you play it on a real instrument, and your runner jumps. MIDI keyboard or microphone, both work.
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