What Scale to Play Over 7b9 Chord

Dominant 7b9 Chord Construction

First, you need to know how 7b9 chords are built :

• 1 (root)
• 3 (major third)
• 5 (perfect fifth)
• b7 (minor seventh)
• b9 (minor ninth)

They can be seen as dominant 7 chords with a b9. You will find below some basic guitar posistions. For more complex 7b9 chord shapes please follow this link.

The Phrygian Dominant Scale

As mentioned before the first scale choice for playing over 7b9 is surely the Phrygian dominant scale, which is actually the fifth mode of the harmonic minor scale. It can be seen as the Mixolydian scale with a lowered 9 (2) and lowered 13th (6) or the Phrygian mode with a major third instead of a minor third (b3). The formula for the Phrygian dominant scale is 1 - b2 (b9) - 3 - 4 (11) - 5 - b6 (b13) - b7.

Other Names for the Phrygian Dominant Scale

• Phrygian major
• Altered Phrygian
• Dominant flat 2 flat 6
• Spanish Gitan
• Jewish
• Spanish Gipsy 

Phrygian Dominant Guitar Shapes

The Mixolydian b2 scale

The Mixolydian b2 scale is the mode V of the harmonic major scale. The interval pattern is 1 - b2 (b9) - 3 - 4 (11)- 5 - 6 (13) - b7. In comparison with the  Phrygian dominant scale, the Mixolydian b2 scale as a natural 13, it should be used with caution, depending on the chord function.
 

Other Names for the Phrygian Dominant Scale

• Dominant b2
• Mixolydian b9 

Mixolydian b2 Chord Shapes

The Half-whole Diminished Scale

The half-whole diminished scale or dominant diminished scale is a symmetric scale built by alternating half-steps and whole-steps. It is important not to confuse it with the whole-half diminished scale which is the opposite. The formula is 1 - b9 -#9 -3 - #11 (or b5) - 5 - 13 (6) - b7
 

The half-whole diminished scale is widely used for soloing over dominant 7th chords, and especially on 7b9 chords. It can bring interesting tensions to your lines by highlighting the #9 and #11 in addition to the b9.
 

Half-whole Diminished Chord Shapes

The Dorian b2 Pentatonic Scale

The next two options for playing over 7b9 chords are pentatonic scales. The formula is root (1) - minor second (b2) - fourth (4) - fifth (5)  and minor seventh (b7). It works perfectly over 7b9 chords.

The Altered Pentatonic Scale

The altered scale is also known as 7b9 pentatonic scale. It is spelled : root (1), minor second (b2) or flat 9 (b9), major third (3), fifth (5) and minor seventh (b7). This is the Phrygian dominant scale without the fourth (4) and the minor sixth (b6).
 

Altered Pentatonic Scale Guitar Shapes

Diminished 7 Arpeggio

Playing a diminished 7 arpeggio (1 - b3 - b5 - bb7) starting on the third of a dominant 7 chord is common trick used by many jazz musicians to highlight the b9. Example with G7b9 (G - B - D - F - Ab) just play  B - D - F - Ab.