Symbols:Am7(b5), Amin7(b5), A-7(b5), Aø7, Am7b5
A Half-Diminished 7th
Construction
Using the scale degree formula, we first start with the A major scale, and number each note in the scale starting from 1 - these are the scale degrees. Next, we use the scale degree formula, in this case 1-♭3-♭5-♭7, to select notes from our enumerated scale. When a chord requires notes that are not in the scale, this is indicated with a flat (♭) or a sharp (#) along with the scale degree; a ♭3, for instance, would be one half-step down from the 3rd scale degree.Alternatively, we can use the interval stack to construct our chord. With this approach, we first start with the root of the chord (A), then move our first interval (m3), which brings us to our second note in the chord (C). We repeatedly apply each of the remaining intervals in the stack to get the full list of notes for our chord.
The diagram below shows how both the scale degree formula and interval stack
methods result in the same selection of notes:
Similar Chords
The following chords are similar to this chord and may be a suitable replacement in certain scenarios.
| Chord Type | Chords |
|---|---|
| 7th Suspended Four Flat 9th | D7sus4b9 |
| 7th Suspended Fourth | D7sus |
| 7th Suspended Second | F7sus2 |
| Added 9th | Fadd9 |
| Diminished | Adim |
| Diminished 7th | F#dim7, D#dim7, Cdim7, Adim7 |
| Diminished Major 7th | AdimMaj7 |
| Dominant 7th | F7 |
| Dominant 7th Flat Fifth | D#7b5, A7b5 |
| Dominant 7th Sharp Fifth | B7#5 |
| Dominant 7th Sharp Five Flat 9th | B7#5b9 |
| Dominant 9th | F9 |
| Major 2nd | F2 |
| Major 6th | D#M6, CM6 |
| Major 7th | G#M7 |
| Major 7th Flat Fifth | D#Maj7b5 |
| Minor | Cm |
| Minor 2nd | Cm2 |
| Minor 6th | Cm6 |
| Minor 7th | Cm7, Am7 |
| Minor 9th Flat Fifth | Am9b5 |
| Minor Added 11th | Cmadd11 |
| Minor Added 9th | Cmadd9 |
| Minor Major 7th | CmM7 |
| Minor Six-Nine | Cm6/9 |
Associated Scales
This chord can be found in the following scales.
| Scale | Roots |
|---|---|
| Blues | A |
| Dorian | C |
| Dorian b5 | A |
| Harmonic Major | G |
| Harmonic Minor | G, E |
| Ionian #5 | G, Bb |
| Locrian | A |
| Locrian bb7 | F# |
| Locrian ♮6 | F#, A |
| Lydian | D# |
| Lydian #9 | D#, C |
| Lydian Augmented #2 | D# |
| Lydian b3 | C |
| Major | Bb |
| Minor | G |
| Mixolydian | F |
| Mixolydian b2 | D |
| Phrygian | D |
| Phrygian Dominant | D, B |
| Phrygian b4 | B |
| Super-Locrian bb7 | F#, D# |
| Ukrainian Dorian | C, A |
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