In my previous post, I discussed how one can use five interlocking chord shapes to play a given major chord along the entire guitar neck. While currently being referred to as the CAGED system (because the shapes correspond to the basic “cowboy chord” shapes of C major, A major, G major, etc.), I prefer to organize the shapes by the string where the chord root is located. Also, by becoming familiar with the function (root, major third, fifth) of each note in the shape, one can begin to expand the basic major triad into any number of advanced chord voicings.
I ended the last post talking about how to get a minor triad chord shape from a major chord. This takes us to the land of chord formulas. I prefer to derive my chords from your basic major scale. A major triad chord is made up of the root, third and fifth of a major scale. The minor triad chord is made up of the root, flatted third and fifth of the major scale. How do you flat a third? In music theory terms, you lower the note by a half step (on a piano, the next lowest key). In guitar terms, just lower the note by one fret. As a example, compare the diagrams below:
Diagram 1 – A Major chord with root on fifth string
Diagram 2 – A Minor chord with root on fifth string
By lowering the note on the second string by one fret (from 14th fret to the 13th), you changed the note that was the major third of the chord to the minor third, making it now a A minor triad. below is another example:
Diagram 3 – A Major chord with root on sixth string
Diagram 4 – A Minor chord with root on sixth string
By lower the note on the third string by one fret, you flatted the chord’s major third making it a minor triad. I recommend going through the exercise of deriving minor triad chord shapes from the other major chord shapes. It will only help you master fretboard harmony that much faster.
The quality of a chord’s third is essential to determining if a chord is a major or a minor triad. It’s important to note that a defining element of what we hear as the blues is the friction one hears between playing the minor third of a chord melodically against the harmony of a major chord.
Next post, we’ll move from triads to our first group of extended chords: the major seventh, the minor seventh and the dominant seventh chords.