So I get how chords are made and all that jazz, the part that throws me off however is when numbers past 7 are added. Where do they come from? Thanks in advance!
By starting all over. Let's take a quick look at the C major scale. It has the following notes:


If we want to make a C9 chord, all we need to do is have the root, 3rd, 5th, b7 and 9. How do we get the 9? By starting over. Watch:

C9 = C, E, G, Bb, D

Notice that we have the D in the C9 chord. While it's the second interval of the scale, it's actually considered the 9, since we have the b7 - we're essentially going past the C at the octave and starting all over. Same with the 11 and 13 chords. We just keep adding more notes.

Does that help?
c d e f g a b c d e f g a b c
1 2 3 4 5 6 7 8 9 10...ect

the nine means the second, just above the root's octave.
Alright ... using the C major scale ...

D = 2
E = 3
F = 4
G = 5
A = 6
B = 7
C = 8 (Octave)
D = 9
E = 10
F = 11
the numbers are tensions, and they are figured out just the same as chord tones (stacking thirds). When refering to tensions, unless they are altered (b9, #9 etc) they are derived from the parallel major scale (meaning if you see a chord labeled as Dm7b513 it would be D F Ab C E G B, even though it would more likely then not be coming from a locrian type chord/scale which would use a flat nine, or be the ii chord in a harmonic minor type situation, its confusing, but thats the way it works). the ninth falls a second above the root (oftentimes but not always plus an octave), the 11th a fourth and the 13th a 6th. so if you see a chord like CMaj7#11b13, you would figure out what notes are, by figuring stacking thirds from the root, and then altering the tensions (in this case lowering the A to an Ab and raising the F to an F#) as indicated. tensions are usually refered to as sitting an octave above the root (meaning 9 instead of 2), though plenty of times they will be voiced in the same octave as the root and other chord tones.
all the best.
(insert self-aggrandizing quote here)
Last edited by tehREALcaptain at Mar 24, 2011,
Quote by joshmckinnon
c d e f g a b c d e f g a b c
1 2 3 4 5 6 7 8 9 10...ect

the nine means the second, just above the root's octave.
It doesn't matter what octave it's in, just how it functions. As tehREALcaptain was saying, the numbers past 7 are extensions, or tensions, which are derived by stacking in thirds past the seventh.
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