I. Intro to Chords

II. Triads and Inversions

III. Sus Chords

IV. Sixth Chords

V. Seventh Chords

VI. Extensions

VII. Add chords and Alterations

VIII. Bass and Polychords

IX. Modern and Chromatic Chords



Part VI: Seventh Chord Extensions (9ths, 11ths, and 13ths)


So we stacked 3 thirds/intervals and got a 4 tone chord...letís take a step further: into the second octave.


Now that the chords are starting to get quite large, we run into a little problem. The number of types of chords for 9ths, 11ths, and 13th chords are smaller that 7ths because there are a lot more tones involved and the chances of a tone clashing with another and causing dissonance increases. Dissonance can be good but a chord made up of 6 minor seconds is considered pleasing by very few.


Letís examine 9th chords first. As usual, there are your typical types, you would expect. First and foremost, let us look at the major 9th chord. Much like the major 7th, you just you all the odd numbers of the major scale up to 9. Maj9 = 1, 3, 5, 7, 9.


[Picture of Maj9]


Also, letís make sure to note its intervals: M3, m3, M3, m3.


Something you should note at this point. You know what the 1, 3, 5, and 7 tones of a scale are, but what about the 8? Well thatís just the octave right? Set of eight notes. The 9? Yes, itís just the 2 of the scale and octave higher. This distinction becomes important in the next section.


The next 9th chord we will look at is the minor 9th. Essentially itís a minor 7th chord with the added 9th of the major scale. Nothing more. Since we know what the minor 7th looks like this should be easy. min9 = 1, b3, 5, b7, 9.


[Picture of min9]


Intervals: m3, M3, m3, M3


Now for the Dominant 9th. Well this is a surprise...itís the dominant seventh with a ninth added. Dom9 = 1, 3, 5, b7, 9


[Picture of Dom9]


Intervals: M3, m3, m3, M3


Those are the most common ones, but there are some more irregular ones as well.  A lot of them cannot be described without knowledge of the following section.


Next is the chord. This is a fairly simple idea as well. Remember 6th chords? This is no more than a 6th chord with an added 9th tone.


This page will be updates soon to include more information on further extensions.