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# Piano Fact

Lesson 31: Chords of a Higher Order

QUESTION: I often come across chords like G9, D11, B13. What exactly do those numbers mean? Can I learn to figure out the chords on my own based upon the numbering system?

ANSWER: The numbers that you see in chord symbols refer to the major scale from which the chord is derived. For example, a C6 chord has the sixth step (or degree) of the C scale, i.e. the A note.

Most of the advanced chords are based on one of two triads:

the major triad which is 1 - 3 - 5 of the scale
the minor triad which is 1 - flat 3 - 5 of the scale

A sixth chord is a major chord (1 - 3 - 5) plus the 6th note of the C scale. The C6 chord is spelled C E G A.

A minor sixth (e.g. Cm6) is a minor chord (1 - flat 3 - 5) plus the 6th note of the C scale. The Cm6 chord is spelled C Eb G A.

So what exactly is 9th? A ninth is the ninth step of the scale.

But doesn’t a scale only have eight steps? Yes, but then it repeats. The eighth step of the scale is the same as the first step. The ninth is the same as the second.

To continue the logic the 11th is the same as the 4th, and the 13th is the same as the 6th. So one way to arrive at the answer quickly is simply to subtract the number ‘seven’ from the number you see in the chord, and add that note of the appropriate major scale. Nine minus seven is two. A ninth is the same as a second. And so on.

So does that mean a sixth chord is identical to a thirteenth? Not exactly. The hidden meaning behind this logic is as follows: When you find a number higher than eight in a chord, then the chord MUST also contain a flat (dominant) seventh. Whereas a C6 chord has the notes C E G A, the C13 contains C E G A and Bb. (The thirteenth probably has a ninth in it as well, and perhaps an 11th, but we won’t get into that right now.)

Remember that a C6 chord functions as a major chord while a C13 functions as a dominant (or 7th) chord. They are not mutually interchangeable. Never.

There are two exceptions to this rule, although they occur quite rarely. When you see the designation “maj” or “add” in a chord symbol, it means you do NOT add the flat seventh; and the chord functions as a major chord. In the case of “maj” you should add the natural 7th. Note the distinctions below.

C9 = C E G Bb D

Cadd9 = C E G D

Cmaj9 = C E G B D

Of course there’s a lot more to chord analysis than that. But this is a start. When you understand how chords work (as opposed to merely memorizing them by rote), your horizons of musicianship greatly expand.

For a basic lesson on constructing chords refer to Lesson 20.

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