D Minor 6th Guitar Tuning

The add9 chord is a major chord with the ninth (second) note added. It is a four note chord with the the ninth (second) in addition to the major triad of root, major third and perfect fifth. The difference between an add9 chord and a ninth chord is that the add9 chord is a four note chord that does not have a seventh and the ninth chord is a five note chord with both the seventh and the ninth.

The minor add9 chord is also a four note chord. It adds the ninth (second) to the minor triad of the root, minor (flatted) third and perfect fifth.