7th chords will be described more in detail.
As you already know, the 7th chords each comprise the basic triad and one 7th note.
C7 comprises:
C・E・G・B♭
Root, 3rd, P5th,♭7th
CM7 comprises:
C・E・G・B
Root, 3rd, P5th, M7th
By adding the M7th note, the sound changes from C to CM7.
Furthermore, by adding B to the C triad, you can get Em triad.
CM7 = Em/C (EmonC)
Thus, Em on C and the CM7 comprise the same notes.
When you are in an ensemble or playing duo with a bass player, the bass player plays the C note and thus, if the guitar player plays Em, CM7 harmony can be obtained.
Edim/C and the C7 comprise the same notes.
See the section ＜Triad＞
In the next chapter, “diatonic scales” will be described.
