If we add the note A to our chord, we engineer an extension to our triad, which creates what we describe as a diminished 7th. You will also see that if you add a further minor 3rd, above the note ...

There’s nothing to stop us continuing up the chord, in a similar vein, adding more minor 3rds as we go. Diminished 7th If we add the note A to our chord, we engineer an extension to our triad ...

All the chords built on other notes in the scale of C are minor, except chord VII - the notes B – D – F, which is diminished. When a seventh is added to a chord this is known as a seventh chord.