Do 9th chords always include the 7th?

by Tret Fure
(Madison, WI)

Question: Is the 9th chord always based on a dominant 7 chord?

Answer

People use the term "9th chord" in different ways. Technically it just refers to a chord which includes the 9th (2nd tone of the major scale).

A dominant 9th chord contains the flat 7th and would be labelled simply as 9 (e.g. A9 B9 C#9).

So if you see the chord letter followed by the 9, or in fact a 13, you'll know it contains the dominant 7th.

Without the dominant 7th, the 9th would be "added" so we'd get an add9 chord (e.g. Aadd9 Badd9 C#add9).

Take a look at the Extended Chords lesson in the Guitar Chord Theory series for more examples of how the 9th is used in chords.