SEVENTH CHORDS
In our previous lesson on Basic Chords and Triads, we learnt that triads are chords formed by stacking third intervals above a root note until there are three chord tones. Can you, then, continue stacking thirds beyond the third chord tone? The answer is, or course you can! When you stack another third interval above a triad to get a fourth chord tone, that's when you get Seventh Chords. They are called Seventh Chords because the fourth chord tone is a seventh interval above the root.
As with the triads, there are a few types of Seventh Chords and in this lesson, we will be covering seven basic types of seventh chords:
1. The Major Seventh Chord
The first type of seventh chord is the Major Seventh chord. It is made up of a major triad with a major seventh interval above the root. The chord symbol for the above C major seventh chord is Cmaj7 or CM7 or C∆7.
2. The Minor Seventh Chord
The Minor Seventh chord is made up of a minor triad and minor seventh interval above the root. The chord symbol for the above C minor seventh chord is Cm7 or C–7.
3. The Dominant Seventh Chord
The Dominant Seventh chord is made up of a major triad with a minor seventh interval above the root. The chord symbol for the above C dominant seventh chord is C7.
4. The Minor Seventh Flat 5 / Half Diminished Chord
The Half Diminished chord (also called Minor Seventh Flat 5) is made up of a diminished triad with a minor seventh interval above the root. If it helps, it might be easier to think of it as a Minor Seventh Chord with a flattened 5th. The chord symbol for the above C Minor Seventh Flat 5 chord is Cm7(b5) or C–7(-5) or Cø7. Note that the chord symbol Cø7 is not to be confused with Cº7 (C diminished 7th) or Cº (C diminished triad).
5. The Diminished Seventh Chord
The Diminished Seventh chord is made up a diminished triad with a diminished seventh interval above the root note. The chord symbol of the above C diminished seventh chord is Cº7.
There a few things of interest to be noted about the diminished seventh chord: 1) each chord tone in the diminished seventh chord is a minor third (or three semitones) away from the next chord tone. 2) Any diminished seventh chord is made up of the same exact notes as the diminished seventh chords formed off its chord tones. For example, Cº7, which is made up of the notes, C, Eb, Gb and A (enharmonic equivalent of B double flat), is made up of the same exact notes as Ebº7, Gbº7, and Aº7. In other words, Cº7 is same chord as Ebº7, Gbº7, and Aº7.
6. The Major Sixth
The Major Sixth chord is made up of a major triad with a major 6th interval above the root. The chord symbol for the above C Major Sixth chord is C6.
7. The Minor Sixth
The Minor Sixth chord is made up of a minor triad with a major 6th interval above the root. The chord symbol for the above C Minor Sixth chord is Cm6 or C–6.