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Ab7b9 Piano Chord

    Piano Diagram of Ab7b9 in Root Position

    Ab 7b9 Chord Root Position Piano Diagram

    An Ab7b9 chord is an altered dominant seventh chord that is built upon the key of Ab. This chord consists of the root Ab, the major third C, the perfect fifth Eb, the minor seventh Gb, and the minor ninth Bbb. The Ab7b9 chord can be used as a substitute for dominant chords only in specific musical contexts. Keep reading to learn more about the music theory that underpins this chord.


    Structure of Ab7b9


    Ab, C, Eb, Gb, Bbb


    R, 3, 5, m7, m9

    How to play an Ab7b9

    To play an Ab7b9 chord, you can use the following voicing: start by playing the root note Ab with your left hand. Then, with your right hand, play the notes C (major 3rd), Gb (minor 7th), and Bbb (natural A, flat 9th).

    Ab + C, Gb, Bbb

    This approach will result in a simplified Ab7b9 chord that includes only the essential notes: the root note, major 3rd, minor 7th, and minor 9th.


    Ab7b9 Chord Equivalencies

    When you remove the root note from a 7b9 chord, it becomes a diminished 7th chord. In the case of an Ab7b9 chord, if you remove the root note Ab, you’re left with the notes C, Eb, Gb, and Bbb, which are equivalent to a Cdim7 chord.

    Ab7b9 without root = Cdim7

    C dim7 = Eb dim7 = Gb dim7 = Bbb dim7

    Diminished 7th chords have a unique quality where each inversion is another diminished 7th chord. So, Cdim7 is enharmonically equivalent to Ebdim7, Gbdim7, and Bbbdim7. Therefore, even if you remove the root note from an Ab7b9 chord, it is still enharmonically equivalent to all of these chords.

    Ab7b9 Chord Inversions


    The Ab7b9 chord has a total of 4 inversions:

    Root Position: Ab C Eb Gb Bbb
    1st Inversion: C Eb Gb Ab Bbb
    2nd Inversion: Eb Gb Ab Bbb C
    3rd Inversion: Gb Ab Bbb C Eb
    4th Inversion: Bbb C Eb Gb Ab

     Piano Keyboard Diagrams

    Ab7b9 Chord - Root Position - Piano Diagram

    Ab7b9 Chord – Root Position


    Chord Inversions on Piano

    Understanding chord inversions is crucial for music theory, as it reveals how chords are constructed. When playing chord inversions on a piano, it’s important to remember that the charts showing the order of notes may not always be playable.

    To properly voice chords on a piano, the notes must be spread across various octaves and positions on the keyboard. This often means deviating from the standard shape of the chord’s inversions, as shown in charts. It’s always a good idea to experiment with different voicings and fingerings to find the most efficient and comfortable way to play the chord, while still maintaining its intended harmonic function and sound.

    Chord inversion charts can help understand the structure and sequence of notes in a chord, but it’s important to be flexible and adaptable when playing them on the piano. With practice, you can find your own unique voicings and develop a personal style that suits your playing needs.

    Music Theory and Harmony of Ab7b9


    The Ab7b9 chord can replace or enhance the Ab7 chord, typically on the V degree, but also on the III degree, and occasionally on other degrees as a secondary dominant chord. However, it has a distinct vibe, so it should be used carefully in the appropriate musical context.

    Before delving into the most frequent uses of this chord, let’s first understand how to build it.


    Building the Ab7b9 Chord: Different Approaches


    Starting from the Ab Major Scale:

    To form a 7b9 chord, you combine the root, the major 3rd, the 5th, the minor 7th, and the flat 9th from a major scale.

    To build an Ab7b9, you can start with the Ab Major scale:


    Ab Major Diatonic Scale up to 13th

    Ab Major Scale


    Ab Major Diatonic Scale up to 13th Keyless Notation

    Ab Major Scale – Keyless Notation


    To create an Ab7b9 chord, apply the formula R, 3, 5, m7, m9 in the following manner:

    1. Begin with the Root note, which is Ab.
    2. Select the major 3rd interval, which is C, and add it to the chord.
    3. Add the 5th interval, which is Eb.
    4. Add the minor 7th interval, Gb.
    5. Finally, select the 9th Bb and subtract a half tone to get the minor 9th, Bbb.

    By following this simple formula, you can create a 7b9 chord from any major scale.


    by Combining Intervals:

    One method to create a 7b9 chord is by combining specific intervals – a major 3rd, a minor 3rd, and another minor 3rd.

    3 + m3 + m3 + m3 = 7b9 chords

    For example, to build an Ab7b9 chord:

    • we start with the root note Ab.
    • We then add a major 3rd interval, which is four half-steps up from the root, to get C.
    • Next, we add a minor 3rd interval, which is three half-steps up from C, to get Eb.
    • Then, we add another minor 3rd so we find the minor 7th Gb
    • and lastly, we add a minor 3rd  interval from Gb, to get Bbb.

    Together, these intervals form the Ab7b9 chord.


    by Combining Chords

    Another way to build a 7b9 chord is by combining a major triad with a diminished triad derived from its 5th.

    To build an Ab7b9 chord, you can blend an Ab Major triad (Ab, C, Eb) with an Eb diminished chord (Eb, Gb, Bbb). The Eb note is shared between the two chords.

    Ab Major + Eb dim = Ab7b9


    How to Use Ab7b9 in a Chord Progression


    The Ab7b9 can work as a substitute or as a passing chord to an Ab7 that can be found in major and natural minor scales. The 7b9 chord is considered a non-diatonic chord, which means that it contains notes that are not found in either the major or minor scales.


    The Most Common Uses of Ab7b9

    Ab7b9 in Db Major and Db minor

    The Ab7b9 chord is commonly used as a dominant chord. In the key of Db major, the Ab7b9 chord can be used as the V7 chord, which leads back to the I chord (Db major).

    Major Scale I ii iii IV V vi vii
    Db Db Maj7 Eb min7 F min7 Gb Maj7 Ab7 ⇒ Ab7b9 Bb min7 Cm7b5
    • Substitute or Passing Chord to the Dominant chord in Db Major


    Ab7b9 as Substitute of Abm7

    The Ab7 chord derived from the harmonic minor scale is commonly used to replace an Abm7 chord in the key of Db minor. In some cases, the Ab7b9 chord can also be used instead of the Ab7 chord, further enhancing the harmonic tension and leading to the Dbm7 chord.

    However, since Db minor is a theoretical key, we’ll refer to its enharmonic equivalent key, C# minor.

    Minor Scale i ii III iv v VI VII
    C# = Db C# min7 D#m7b5 E Maj7 F# min7 G#m7 ⇒ G#7 ⇒ G#7b9 = Ab7b9 A Maj7 B7
    • Substitute or Passing Chord to the Dominant chord in C# minor as G#7b9


    Ab7b9 in a I – III7 Progression

    The Ab7b9 chord is used as a substitution for the III degree in an I – III7 chord progression, which traditionally features an Ab minor chord. This chord progression, represented by the chords Fb Maj7 and Ab7, can accommodate the Ab7b9 chord in place of the expected Ab minor chord. The Ab7b9 chord provides a dissonant augmented triad that offers a unique flavor to the progression.

    As before, we are in a theoretical key so we’ll use the equivalent E major key.

    Major Scale I ii iii IV V vi vii
    Fb = E E Maj7 F# min7 G#m7 ⇒ G#7 ⇒ G#7b9 = Ab7b9 A Maj7 B7 C# min7 D#m7b5
    • Substitute or Passing Chord to the Mediant chord in E Major as G#7b9


    Ab7b9 in Bb minor

    While the Ab7b9 chord can be used in the key of Bb natural minor, it may not be the most common use of this chord. In fact, the resolution to Bb minor may be less strong than Db major or Db minor.

    Minor Scale i ii III iv v VI VII
    Bb Bb min7 Cm7b5 Db Maj7 Eb min7 F min7 Gb Maj7 Ab7 ⇒ Ab7b9
    • Substitute or Passing Chord to the Leading Tone chord in Bb minor (less common)


    Ab7b9 as Substitute for a Secondary Dominant 7th chord

    A secondary dominant is a chord that doesn’t belong to the main key of a musical piece but is used to create a strong pull toward another chord that does. In Western music, the fifth scale degree has a dominant function and generates tension that resolves to the first scale degree chord (I). A secondary dominant chord is utilized to create the same dominant function but towards a different chord, resulting in a brief departure from the main key.

    For instance, in the key of Gb major, Db7 is the V chord and resolves to the I chord (Gb Maj7). To create a secondary dominant, another chord is added between Gb Maj7 and Db7, which creates a powerful pull towards Db7. In this scenario, incorporating an Ab7 generates a pull towards Db7 since Ab7 is the V chord in the key of Db.

    | Gb Maj7 | Db7 |

    | Gb Maj7 | Ab7 | Db7 |


    Instead of using a regular Ab7 chord, you can also use the Ab7b9 chord in place of or together with it. This substitution or addition can add more tension and complexity to the progression, leading to a more interesting and dynamic musical result.

    | Gb Maj7 | Db7 |

    | Gb Maj7 | Ab7/Ab7b9 | Db7 |


    Ab7b9 as Dominant Chord in Db Major

    In the key of Db major, the dominant chord is Ab7. However, this chord can be substituted or paired with an Ab7b9 chord for a more complex and interesting sound. Let’s explore how this can be done.

    I ii iii IV V vi vii
    Db Maj7 Eb min7 F min7 Gb Maj7 Ab7 Bb min7 Cm7b5


    Ab7b9 Chord Progressions as V degree

    Try playing these chord progressions to get an idea of how Ab7b9 functions near the dominant chord. Most of the time, I like to use it followed by an Ab7 or preceded by an Ab7#9 but feel free to experiment.

    ii V I
    ii V I
    Eb min7 Ab7b9 | Ab7

    Ab (C, Gb, A) | Ab (C, Gb, Ab)

    Db Maj7


    I IV vi V
    I IV vi V
    Db Maj7 Gb Maj7 Bb min 7 Ab7b9 | Ab7


     I IV ii V iii vi ii V
    I IV ii V iii vi ii V
    Db Maj7 Gb Maj7 Eb min7 Ab7b9 | Ab7 F min7 Bb min7 Eb min7 Ab7b9 | Ab7


    Ab7b9 as Dominant Chord in Db minor

    Check G#7b9 in C# minor


    Ab7b9 as III7 Degree in Fb Major

    Check G#7b9 in E Major


    Ab7b9 as Leading Tone Chord in Bb minor

    In the key of Bb minor, the Ab7 chord is built on the leading tone, which is the seventh note of the scale. This chord can be replaced or modulated by an Ab7b9, although it may not be the most ideal position for this chord. Nonetheless, it can still be a valid option in certain musical contexts.

    i ii III iv v VI VII
    Bb min7 Cm7b5 Db Maj7 Eb min7 F min7 Gb Maj7 Ab7


    Ab7b9 as VII degree – Chord Progressions


    i iv VII i
    i iv VII i
    Bb min7 Eb min7 Ab7b9 | Ab7 Bb min7


    i iv VII III
    i iv VII III
    Bb min7 Eb min7 Ab7b9 | Ab7 Db Maj7


    Circle Progression
    i iv VII III VI ii V7 i
    Bb min7 Eb min7 Ab7b9 | Ab7 Db Maj7 Gb Maj7 Cm7b5 F7 Bb min7


    Alternative Ab7b9 Nomenclature

    • Ab 7b9
    • Ab 7/b9
    • Ab 7(b9)
    • Lab 7/b9
    • Ab dom7b9
    • Ab 7th b9th
    • Ab 7th flat 9th
    • Ab Dominant 7th b9
    • Ab Dominant Seventh Flat Ninth



    The chord progressions and examples presented in this post provide a comprehensive overview of the most common uses of the Ab7b9 chord. It’s important to note, however, that there are many advanced harmony-related topics that could not be included due to space constraints. These topics include chord progressions built on harmonic and melodic scales, modal scales, hidden tonality, secondary dominants and other chord substitutions, non-functional harmony and atonal music, modal interchange and borrowed chords, voice leading and counterpoint, chromatisms, jazz harmony…I mean, music theory is a huge topic!

    Although I couldn’t cover all of these topics in my post, I encourage readers to continue exploring these areas in their own study and research. By expanding your knowledge in these advanced areas of music theory, you can gain a deeper understanding of the harmonic possibilities that exist beyond the basics presented here.


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