A seven chordA7

Built from

• Aroot
• C♯major 3rd
• E5th
• Gflat 7th

The flat 7th rubs against the major 3rd, and that tension wants to resolve.

Hear it in a progression

• ii–V–I

  The backbone of jazz. In D major.

  Capo and transpose

  1. Em7ii7
  2. A7V7
  3. Dmaj7Imaj7
  4. Dmaj7Imaj7

• Blues opening

  The first four bars of a twelve-bar blues. In A major.

  Capo and transpose

  1. A7I7
  2. D7IV7
  3. A7I7
  4. A7I7

Where it goes next

Thinking in D major, where it is the V7 chord.

• Dmaj7

  Imaj7. The strongest pull in music: tension resolving home.

• Bm7

  vi7. The fake-out: you expect home, you get the relative minor.

Sounds close

• C♯dim7

  It is this chord without its root: a darker stand-in. Both have C♯, E and G.

• F♯m7

  Shares 3 of its notes. Both have A, C♯ and E.

• E♭7

  Tritone substitute: swaps in for it in jazz. Both have C♯ and G.

• C

  Shares 2 of its notes. Both have E and G.

Scales that fit

Notes you can play over this chord, simplest first.

• A major pentatonic
• A minor pentatonic
• A blues
• A mixolydian

Keys it lives in

• D majoras V7
• B minoras VII7