11. FOUR NOTE CHORDS

Up to now, we have explained the construction and graphic representation of Major, minor, Augmented and diminished chords (in this last case, with 3 and 4 notes). These chords include all possible chords built by superimposing two Major o minor 3^rd intervals. And, as we have seen, all of them have a very simple geometric shape on the Harmonic Wheel.

The superimposition of three Major o minor 3^rd intervals, gives 8 possibilities. However, the case of three Major 3^rds results in an Augmented chord, which has only 3 different notes and has been studied in the last chapter. The other 7 possibilities actually correspond to 4 note chords, but the case of three minor 3^rds results in a diminished chord, which has been studied in the last chapter, too. So, we shall go on with the construction and graphic representation of the remaining 6 types of chords. They have been grouped by couples in order to show the existing symmetries. In all cases, the Root of every chord has been marked with  and the rest of the notes with .

Now, besides of the 3^rd and 5^th intervals, a 7^th will appear between the first and the last note in each chord. Relating to the symbols used to represent the chords, the most simple as well as universally accepted ones have been chosen. Particularly, the symbol “7” is used to indicate the minor 7^th and the symbol “” for the Major 7^th. From now on, we shall not repeat that the enharmonic notes not following the series of 3^rd intervals must be discarded, as it has already been mentioned several times.

A Major 7^th Chord is a 4 note chord, built by superimposing a M 3^rd, a m 3^rd and a M 3^rd intervals (in this sequence). Thus, for example, the C Major 7^th chord is composed by notes C, E, G, B. This chord is represented by “C”.

A minor 7^th Chord is a 4 note chord, built by superimposing a m 3^rd, a M 3^rd and a m 3^rd intervals (in this sequence). Thus, for example, the A minor 7^th chord is composed by notes A, C, E, G. This chord is represented by “Am7”.

Figure 15. Graphic representation of C and Am7 chords on the Harmonic Wheel.

A Dominant 7^th Chord is a 4 note chord, built by superimposing a M 3^rd, a m 3^rd and a m 3^rd intervals (in this sequence). Thus, for example, the G Dominant 7^th chord is composed by notes G, B, D, F. This chord is represented by “G7”. It is worthwhile to point out that, in this chord, a d 5^th (tritone) is formed between the 3^rd and the 7^th of the chord (in the example, between B and F).

A half-diminished Chord is a 4 note chord, built by superimposing two m 3^rd and one M 3^rd intervals (in this sequence). Thus, for example, the B half-diminished chord is composed by notes B, D, F, A. This chord is represented by “B”. It is worthwhile to point out that, in this chord, a d 5^th (tritone) is formed between the root and the 5^th of the chord (in the example, between B and F).

Figure 16. Graphic representation of G7 and B chords on the Harmonic Wheel.

An Augmented, Major 7^th Chord is a 4 note chord, built by superimposing two M 3^rd and one m 3^rd intervals (in this sequence). Thus, for example, the C Augmented, Major 7^th chord is composed by notes C, E, G, B. This chord is represented by “C+”.

A minor, Major 7^th Chord is a 4 note chord, built by superimposing one m 3^rd and two M 3^rd intervals (in this sequence). Thus, for example, the A minor, Major 7^th chord is composed by notes A, C, E, G. This chord is represented by “Am”.

Figure 17. Graphic representation of C+ and Am chords on the Harmonic Wheel.