Intervals Series Part 3: Completing The Interval List

In the last two lessons we have worked our way up to this list of Interval names/numbers:

C     D     E     F     G     A     B     C     D     E     F    G    A    B    C
R     2     M3   4     5      6     M7   R     9     M3 11    5    13   M7  R

Hopefully this list looks familiar to you and you understand it. If not please see the previous lessons.

The list above works with a two octave scale showing the notes Interval relationship to the Root C.

And, you can see that we've accounted for the common Interval names/numbers that are used in building common Triads and Extended chords (the R, M3, 5 and M7 are constant across each octave).

Let's take it another step further. Let's look at the other Intervals and their octaves. By doing so we can trim the scale down to one octave and not miss any notes.

Notice in the list above how:

D = 2 and 9
F = 4 and 11
A = 6 and 13

The 2 is the same note in the scale as the 9. The 4 is the same note in the scale as the 11. The 6 is the same note in the scale as the 13.

The Intervals are commonly written out like this, trimming down what I just listed.

2/9
4/11
6/13

In the C Major scale:

D = 2/9
F = 4/11
A = 6/13

Generally you can use the term "2" interchangeably with "9", and "4" for "11", and "6" for "11". Mainly because they are the same note names, even though they are in different octaves.

When Extending chords higher than the four note "extended" chord you generally use the "higher number", i.e. 9, 11, 13. Like Cmaj13, not Cmaj6...or maybe Cmaj11, not Cmaj4.

When building what are called "Add" chords you can use either the high or the low number. Like Cadd6 is is the same notes as Cadd13, Cadd2 is the same notes as Cadd9, Cadd4 is the same notes as Cadd11.

In a future lesson we'll detail what the Chord Formulas look like for these Extended and Add Chords.

There are guidelines to how chords should be written or labeled, but in reality the guidelines can get blown out of the water as you could see them written either way in a book or on someone's chart.

You just want to remember:

2=9
4=11
6=13

Ok, now let's streamline the Intervals in the C Major scale and redraw the scale again to get this:

C    D     E       F      G      A       B      C
R   2/9   M3   4/11   5     6/13   M7     R

Now we can look at the scale in one octave and understand the Interval relationship to the Root. This is big progress.

In the next lesson we are going look at the Interval relationship of ALL the notes from the Root, a Chromatic scale. Don't worry, if you got this far the rest should be very understandable.