Part 2: Adding a 6th or 7th
In jazz, chords typically have an added 7, or the less common though still widely used 6. This is the messiest part due to inconsistent patterns and odd rules.
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 7ths.
- 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
- You can add ∆7s to any triad.
- 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.
- Ex. Caug∆7 or C+∆7 are more commonly written C∆7#5 or as a slash chord.
Adding the 7 to a Diminished Triad
7ths 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.
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- Cø7 = means a diminished triad with a minor 7
- C-7b5 = means a minor 7 chord with a flatted 5th, 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.