Ab7

Ab7, or A-flat dominant seventh, is a four-note chord built on the root A-flat. Its common spelling is Ab–C–Eb–Gb, where Ab–C–Eb forms a major triad and Gb provides the minor seventh above the root. The chord is enharmonically equivalent to G#7, but Ab7 is the standard spelling in the key of Ab or Db-related harmony.

Function and harmony: Ab7 serves as a dominant seventh chord (V7) and typically resolves to a tonic chord on Db, making it the dominant in keys where Db is the tonic (for example in Db major or Db minor). It can also appear as a secondary dominant (V7/IV) in the key of Ab major, where it functions to lead to the IV chord, Db. In jazz and popular music, Ab7 is used to create tension before the return to the tonic or to pivot to related keys.

Voicing and usage: Ab7 can be played in root position or in any inversion (C–Eb–Gb–Ab; Eb–Gb–Ab–C; Gb–Ab–C–Eb). Jazz players often voice Ab7 with added tensions such as 9, 11, or 13 to enrich color, though the basic form remains Ab–C–Eb–Gb. The chord appears in many genres, including blues, funk, and pop, and is a common component of II–V–I progressions in Db major.

Summary: Ab7 is the dominant seventh built on A-flat, essential for establishing a pull toward Db harmony. It has straightforward equal-temperament spellings and a flexible role across classical-inspired harmony and modern jazz and pop contexts.