Altered dominant 7th chords

In an altered dominant 7th chord, you add altered tensions (b9, #9, #11 or b13) instead of the natural tensions (9, 11* or 13) to the basic chord tones.

b9←9→#9
11→#11
b13←13

*) The 11 (4th) is normally not added to a V7 chord. If you use the 4th, you omit the 3rd and the result is a sus4 chord.

Notation

  • If a dominant 7th chord is notated with the suffix alt (e.g., G7alt), you can choose which altered tensions to add to the V7 chord.
  • Sometimes the tensions are written explicitly in the chord symbol, e.g., G7(b9), G7(#9), G7(b13), G7(b9,b13), etc., either because the composer/arranger intends it or because a transcription shows exactly what was played on a specific recording.
    Especially in tunes with frequent chord changes (1-2 chords per bar at medium or up tempo), such symbols are often treated as a general V7alt. In practice you might play G7(b13) instead of G7(b9) if it sits better on the fretboard.
  • Often no tensions are written at all. Whether a G7 is played as a plain G7, as G7 with 9 or 13, or as G7alt depends on the style, melody, and the overall chord progression.

C7alt

G7alt

Where do altered V7 chords occur?

V → I

If a dominant 7th chord resolves to a chord whose root is a 5th lower (a 4th higher), you can (and sometimes should) use altered tensions.

Two-Five-One in major

In major 2-5-1, use natural or altered tensions on the V7 chord; mixed forms like G7(b9,13) also work.

Two-Five-One in minor

In a minor 2-5-1 progression, you typically use altered tensions. Since the 5th scale degree in a minor key corresponds to the 3rd degree in its relative major, b9 and b13 are diatonic to the scale context and therefore sound natural.

#11 with 9 and 13

If the V7 does not resolve from V to I by a 5th, you can add #11 and/or the natural tensions 9 and 13 to the dominant chord. The #11 has a special status and often appears even when other tensions are not altered.

IIm7 → bII7 → Imaj7

IVmaj7 → bVII7 → Imaj7