Lesson 16 - Diminished Seventh Chords
A dimished seventh chord is a dimished triad with a seventh added to it. The most common one is the fully diminished seventh chord (highlighted in gold). It is created by adding a dimished seventh to the triad, or by adding a minor third interval above the dimished fifth. This chord contains three minor third intervals. This makes the tonal focus undefined.
Root-third interval: minor 3rd
Root-seventh interval: dimished 7th
There are a couple of other types of dimished triads. One contains a dimished triad with a minor seventh. This is called a half-dimished seventh chord. The order contains a major third, dimished fifth and minor seventh above the root, and though it can be written as a dimished seventh chord, it is generally considered an augmented sixth chord.
©2004 Keith Prater