Chord Scales - Part 2: Modes
(09 Apr 03)
Approach No.2 - Chords 'n Tensions
Actually, this approach is a continuation of what I have talked about in Chord Scales - Part 1. Remember how we derived 7th chords by stacking up thirds that are diatonic to the key and scale. That's how it looked like:
Of course we can continue to stack up diatonic thirds. The result is that we get 5,6, and 7 note chords. Note that the notes added to our basic 7th chords are called tensions, meaning they are not part of the 7th chord anymore, but can be incorporated to create a special mood or tension.
Let's examine each individual chord:
I maj7
If we add another diatonic third to the basic Cmaj7 chord we get a major ninth on top of the chord, which in our case is the note D.
Note that when tensions that are major or perfect are indicated in a chord symbol it is common to write the plain number without the "M"or "P", as it is in use with intervals.
If we add another diatonic third to the Cmaj7(9) chord we get a perfect eleventh on top of the chord - in our case the note F.
By adding another third on top of the Cmaj7 (9 11) we get a major thirteenth on top of the chord.
Notice that we now have stacked up all seven notes of the C major scale in thirds starting on the note C. We can divide these 7 notes into 2 categories: chord tones (1, 3, 5, 7) and tensions (9, 11, 13)
The scale: If we write out all the notes of the Cmaj7(9 11 13) chord in form of a scale, meaning in ascending order we close the circle and are back at our C major scale (tensions 9,11,and 13 of the chord become M2, P4, M6 of the scale). Speaking in terms of modes this is Ionian.
The avoid notes: Avoid notes are tensions that create a dissonant interval to a basic chord sound, which, in turn, results in a loss of stability.
Example: the interval of a minor ninth is a very strong dissonance. It is strongly recommended to not use this interval (Do you remember that we have already talked about this in the article "7th Chords"?)
Now take a look at the tensions of Cmaj7 above - there is a b9 interval between the M3 and tension 11. As a result we will avoid using tension 11 with a major7 chord.
This does not mean that you are not allowed to play this note while improvising, but you should be careful that you use it as a passing note and do not play it for a long time. Furthermore, I advise you to never include the 11th within a maj7 chord symbol.
(Try this - record a Cmaj7 and then play or sing F as a single note on top of it - interesting, isn't it? Also, notice how the F has a strong tendency to resolve to the E)
Imaj7 Overview
II m7
Here are the tensions for Dm7 if we continue to stack up diatonic thirds:
The scale: It's probably not a big surprise that the notes of a Dm7(9 11 13) are equal to the D Dorian mode.
The Avoid notes: The avoid note is tension 13. Although it doesn't create a b9 interval within the chord itself there's a harmonic reason for avoiding it. I'll make it short: IIm7 - V7 - Imaj7 is one of the strongest cadences in music. If you incorporate tension 13 in the IIm7 chord you anticipate the sound and function of the V7 chord which "destroys" the cadence.
IIm7 Overview
Here's the rest of the list in a brief version:
III m7
IIIm7 Overview
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IV maj7
IVmaj7 Overview
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V 7
V7 Overview
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VI m7
VIm7 Overview
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VII m7b5
VIIm7b5 Overview
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