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