Chord Theory: Part 2

Extending Triads

Now we have looked at the basic triad chords it is time to start looking at how other chords are constructed. We can add one or more notes onto the basic major, minor and diminished triad to form more interesting and harmonically rich chord voicings.

The whole process of extending chords is not complicated at all, despite the fancy names some of these chords produce. We are simply adding notes onto the basic triad chord in order to make them more interesting. Always think in terms of chords as being nothing more than a collection of notes taken from a scale. The more notes you add to the triad the more harmonically dense and jazzy it sounds. Sometimes adding more notes to a chord can really add something special to the harmony but sometimes it can make things sound cluttered. It is up to you to learn when and when not to use rich sounding chords.

The first chord type we will look at is the major 7 chord. It is a major triad with an added major 7th note. If we look back at the C major scale we can see that the seventh note of C major is a B, which is a major third above the last note in the C major triad (G)

C D E F G A B

The result of this added seventh note is shown below

If like me you like to think visually you will see that all we are doing to create these seventh chords is starting at the root and adding every other note. You can move this pattern along the scale to harmonise it. For example the next chord along would start at D and take every other note to form a Dm7 chord.

D E F G A B C

We create a minor seven chord by adding a flat seven note to the minor triad. If we start on the D note of the C major scale we can see that by going up a third from the last note of the D minor triad (A) we get to a C note. C is the b7th note of this scale.

D E F G A B C

We now have a D minor triad with an added C note. The Dm7 chord contains the notes

D F A C

Our next chord type we need to look at is an important one. The dominant seven chord is a major triad with a minor seven note added to it. The dominant seven chord in major scale harmony is important because it wants to resolve strongly to the root of the scale. In a major scale the chord built on the fifth note is always a dominant seven chord and wants to resolve to the first note of the scale. In the key of C the fifth note is G and so we have a G7 chord that wants to resolve to a C major chord. Let’s look at the notes of the G7 chord. Starting at G we move up a major third to get a B note, up a minor third to a D and finally up a minor third to get to an F. So the notes of our G7 chord are

C D E F G A B C D E F G

All we have done here is simply added a flat seventh note to a G major triad.

Our final chord type to look at is the minor 7 flat 5 chord. The minor 7b5 chord is built form a diminished triad. It contains the intervals 1, b3 b5 b7. Again using the Key of C as an example if we build a chord from the B notes in thirds we get

C D E F G A B C D E F G A B C

So the notes of our Bm7b5 chord are

B D F A

In the next lesson we will look at extending these four note chords even further

Next: Part 3