WEDNESDAY, March 4, 2020
Extensions of three note chords…
For the most part four note chords are extensions of triads or suspensions. They are built directly from Mixolydian numbering, which is used for the numbering. Major, minor, diminished and augmented are all considered triads because they all CAN be written in this manner – although diminished and augmented often are not.
Always use Mixolydian for the numbers.
These are the basic four seven chords that come directly from modes:
- Major 7
- Dominant 7
- Minor 7
- Fully diminished.
There are also suspended seven chords and six chords…
- Major 6
- Minor 6
- Major 7 with suspended 4
- Major 7 with suspended 2
- Doubly suspended major 7, which technically has 5 notes but belongs in this group.
- Dominant 7 with suspended 4
- Dominant 7 with suspended 2
- Doubly suspended dominant 7, which technically has 5 notes but belongs in this group.
Finally, there are altered chords…
- Augmented dominant 7 chord
- Dominant seven with flat 5
- Major with b5
- Minor with b6
White key 7 chords…
For the most part four note chords are extensions of triads. Four note chords can be inverted, but for the moment let’s not worry about that.
The most important 7 chords are those that can be played on all white keys in the key of C major, and there are four of them.
- X7 (G7)
- Xmaj7 (Cmaj7 and F maj7)
- Xm7 (Dm7, Em7 and Am7)
- Xm7b5 or X half-diminished (Bm7b5 or B half diminished
These four basic 7 chords can be altered by raising or lowering some note within the chord. Here are a few possibilities:
- X7 4:2 sus
- X aug7