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A#9 Piano Chord

    Piano Diagram of A#9 in Root Position

    A#9 Chord - Root Position - Piano Diagram

    An A#9 chord is a dominant seventh chord built upon the key of A# with an extra 9th note. The A#9 chord can be used on the fifth degree of several scales as a variation of a dominant 7th chord. The 9th adds an extra layer of dissonance. Keep reading to understand the music theory behind this chord.


    Structure of A#9


    A#, Cx, E#, G#, B#


    R, 3, 5, m7, 9

    Playing Extended Chords on Piano

    Extended chords are commonly used in piano playing, but they can be tricky to play in their entirety due to the large number of notes involved. To make these chords more manageable, pianists often omit certain notes, such as the root or the 5th. Another technique is to split the chord between both hands, playing either full or partial chords in each hand.

    However, even when notes are omitted or split between hands, extended chords can still create complex and dense harmonies. When these chords are inverted, the resulting clusters of notes can be particularly challenging to voice effectively.


    A#9 Chord Inversions


    The A#9 chord has a total of 4 inversions:

    Root Position: A# Cx E# G# B#
    1st Inversion: Cx E# G# A# B#
    2nd Inversion: E# G# A# B# Cx
    3rd Inversion: G# A# B# Cx E#
    4th Inversion: B# Cx E# G# A#


     Piano Keyboard Diagrams

    A# 9 Chord - Root Position - Piano Diagram

    A#9 Chord – Root Position

    Chord Inversion on Piano

    Understanding chord inversions is an essential aspect of music theory as it helps to explain how chords are constructed and used in progressions. When playing chord inversions on a piano, it’s important to keep in mind that the diagrams used to illustrate the order of notes may not always be practical to play.

    To achieve the proper chord voicings on a piano, you need to distribute the notes of the chord across various octaves and positions on the keyboard. This often means that the basic shape of the chord’s inversions shown in diagrams may not be the most convenient or comfortable way to play the chord.

    While chord inversion diagrams can be useful in comprehending the structure and sequence of notes in a chord, it’s recommended to experiment with different voicings and fingerings to find the most efficient and comfortable way to play the chord while still preserving its intended harmonic function and sound.

    Music Theory and Harmony of A#9


    The A#9 chord is an extension of A#7, which means you can add the 9th note to the A#7 chord to create a unique and complex sound. You can use the A#9 chord in all the positions where the A#7 chord can be played. However, keep in mind that some positions may not work as well as others when using A#9 instead of A#7.

    You may want to try out the A#9 chord as an alternative to the A#7 chord in different positions. Check out the A#7 chord page for ideas on where to start experimenting. This will help you determine which positions work well with the A#9 chord and which ones may not be as effective.


    Building the A#9 Chord: Different Approaches


    Starting from the A# Major Scale

    To form an A#9 chord, you combine the root (A#), the major 3rd (Cx), the 5th (E#), the minor 7th (G#), and the major 9th from the A# scale (B#). To build it, you can start with the A# Major scale:


    A# Major Diatonic Scale up to 13th

    A# Major Scale


    A# Major Diatonic Scale up to 13th - Keyless Notation

    A# Major Scale – Keyless Notation


    To create an A#9 chord, apply the formula R, 3, 5, m7, 9 in the following manner:

    1. Begin with the Root note, which is A#.
    2. Select the major 3rd interval, which is Cx, and add it to the chord.
    3. Add the 5th interval, which is E#.
    4. Add the minor 7th interval, which is the 7th (Gx) less a half-step, G#.
    5. Lastly, add the 9th, which is B#.

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


    by Combining Intervals

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

    3 + m3 + m3 + 3 = Dominant 9th Chords

    For example, to create an A#9 chord:

    • we start with the root note A#.
    • We then add a major 3rd interval, which is four half-steps up from the root, to get Cx.
    • Next, we add a minor 3rd interval, which is three half-steps up from Cx, to get E#.
    • We add another minor 3rd interval to get G# and
    • finally, we build a major 3rd from G# and we end up with B#.

    When we play these five notes together – A#, Cx, E#, G#, and B# – we get the A#9 chord.


    by Combining Chords

    Another method to build dominant 9th chords is by combining a major triad with the minor chord built on its fifth note.

    To create an A#9 chord, for instance, you can combine an A# Major triad with an E# minor chord. These two chords share the note E#, and when played together, they form an A#9 chord.

    A# Major + E# minor = A#9


    How to Use A#9 in a Chord Progression


    The A#9 chord can be seen as an extension of the A#7 chord and is often used in a similar way as a dominant 7th chord. In fact, the A#7 chord contains the same notes (A#, Cx, E#, G#) except for the additional 9th note (B#) in the A#9 chord.

    Since the A#9 chord includes the dominant 7th note (G#), it has a similar function to the A#7 chord in creating tension and preparing for the resolution to the tonic chord. Therefore, in most cases, the A#9 chord can be used as a substitute for the A#7 chord, and vice versa, depending on the desired musical context and sound.

    These tables show the harmonized major and natural minor scale where you can find an A#7 that can be replaced by an A#9 but I suggest referring to the posts on dominant 7th chords to learn more fancy uses and contexts in which a dominant 9th chord can be played.

    It’s important to keep in mind that D# Major and B# minor are considered theoretical keys and not commonly used in practice. This is mainly due to their complex nature, with a high number of accidentals. It’s more convenient to refer to their enharmonic equivalent keys (Eb Major and C minor), as they involve fewer accidentals.


    on D# Major Scale

    Major Scale I ii iii IV V vi vii
    D# = Eb Eb Maj7 F min7 G min7 Ab Maj7 Bb7 ⇒ Bb9 = A#9 C min7 Dm7b5
    • Dominant chord in Eb Major as Bb9


    on B# minor Scale

    Natural Minor  i ii III iv v VI VII
    B# = C C min7 Dm7b5 Eb Maj7 F min7 G min7 Ab Maj7 Bb7 ⇒ Bb9 = A#9
    • Leading Tone chord in C minor as Bb9


    A#9 as Dominant Chord in D# Major

    A#9 as the Leading Tone chord in B# minor

    Check Bb9 in C minor


    Alternative A#9 Nomenclature

    • A# 9
    • La# 9
    • A# 9th
    • A# 7/9
    • A# dom9
    • A# Ninth
    • A# Dominant 9
    • A# dominant 9th
    • A# Dominant ninth

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