Part 2: Adding a 6th or 7th

Adding a Minor 7

• 7 added to a triad means add the minor 7 interval to the chord.
  • C7 = C E G Bb = a major triad with a minor 7 = dominant 7
  • C-7 = C Eb G Bb = a minor triad with a minor 7 = minor 7

• 7s over augmented triads are the same but often get written out of order.
  • Ex. C+7, which follows the pattern. I have seen C7+ but it’s rare.
  • Ex. C7aug, can also be written Caug7.
  • Ex. C7#5, is how I prefer to write this chord.
    • We’ll look at this again in Part 4.
  • All of these = C E G# Bb = augmented 7

• 7s over suspended chords can be written two different ways. Both are common.
  • Ex. Csus7 and C7sus both mean C F G Bb = suspended 7

Adding a Major 7

Confusingly, our chord notation system prioritizes the minor 7 interval over the major 7. We need an additional symbol to indicate major 7^ths.

• To add a major 7, write maj7, ma7, M7, or my preferred ∆7.
  • You can add ∆7s to any triad.
    • Usually, this is over major, minor, and occasionally diminished.
  • Ex. C-∆7 = C Eb G B = a minor triad with a major 7 = minor major 7
  • Ex. Co∆7 = C Eb Gb B = a diminished triad with a major 7 = diminished major 7
• NOTE: now you see why, if we only want a triad, we don’t write C∆. As ∆ affects the 7, not the triad, many folks will assume you meant to add the major 7 also.
• Augmented and suspended major 7 chords, while possible, are rare.
  • Ex. Caug∆7 or C+∆7 are more commonly written C∆7#5 or as a slash chord.
    • We’ll see this again in Part 4: Adding Altered Notes.
  • Ex. Csus∆7 or C∆7sus are extremely rare. I can’t think of a single example.

Adding the 7 to a Diminished Triad

7^ths over diminished triads are special cases too.

• 7 written after a diminished triad adds a diminished 7 to the chord.
  • Ex. Co7 = C Eb Gb Bbb = fully diminished 7
  • NOTE: “Bbb” is correct, but folks will simplify this to “A” most of the time.

The Half-Diminished Chord (ø7)

A diminished triad with a minor 7 is called half-diminished. As writing the 7 symbol over a diminished triad indicates the fully diminished chord, when we want half-diminished, we write it differently. There are two options.

• • Cø7 = means a diminished triad with a minor 7
  • C-7b5 = means a minor 7 chord with a flatted 5^th, giving us the same notes.
  • Ex. Cø7 and C-7b5 = C Eb Gb Bb
    • As I like shorthand symbols, I prefer ø7.

Adding 6ths

The 6 is common in Trad and Swing music, but you’ll still see it in modern songs.

• 6 after any triad adds a major 6 interval, but is really only used on major and minor.
  • Ex. C6 = C E G A
  • Ex. C–6 = C Eb G A
• While there’s no rule against adding a 6 to other triads, it’s not common practice. I’d avoid it as there’s probably a better way to write what you want.
• In practice, a 6 is used instead of a 7.
• If you want a 6 and 7, you’d write 13 which we’ll discuss later.
• NOTE: when improvising, you can almost always treat a 6 chord like a major 7 chord. We typically build our melodies with the same scales and vocabulary.