In my previous post, I began to talk about chords with extended harmony. Extended harmony could be defined as intervals greater than an octave. Last post we talked about ninth chords. With this post we will discuss eleventh and thirteenth chords.
As we did with ninth chords, lets extend the major scale into the next octave:
Scale Step : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
C major scale : C D E F G A B C D E F G A B C
The interval of the eleventh is enharmonically the same as a fourth but when considering the eleventh interval played with a chord based on the major triad, we encounter a little problem. The eleventh (or fourth) “rubs” against the major third of the triad. It’s akin to playing a major triad and a suspended triad at the same time. That is why the eleventh interval is usually altered to a #11 (such as a C major 7 #11 or a C7 #11) when played against the major triad. By making the eleventh sharp, you eliminate that half step “rub” with the major third. I will discuss #11 chords in my next post when I talk about altered chords. Playing the eleventh with a minor chord is another story. Because the minor triad has a flatted third, there is no half step rub and as a result, minor eleventh chords are not as rare a sighting as a major or dominant eleventh chord.
Since the eleventh as synonymous with the fourth, I usually visualize the eleventh as two frets lower than the fifth. Taking a A minor 7th chord with the root on the sixth string as an example (diagram 1A), we can make it a A minor 11 chord by lowering one of the fifths (in this case, the one located on the fifth string) by two frets (diagram 1B).
For the sake of playable fingering, it’s sometimes necessary to replace the chord’s fifth with a different chord color, in this case the 11th. As I stated in a previous post, if the chord does not have an altered fifth interval (#5 of b5), then the chord’s fifth can usually be replaced
A thirteenth interval is enharmonically synonymous (how’s that for a tongue twister) with the interval of a sixth. A 13th chord can be differentiated from a sixth chord however by the presence of the 7th. If the chord has either a natural or a flatted 7th, the addition of the sixth would make it a 13th chord. Otherwise it would be considered a sixth chord.
As I do with the other intervals, I visualize the 13th interval in relation to the notes in the base triad. I look at the 13th (or 6th) as two frets higher than the chord’s perfect fifth. In diagram 2A, we have a A7th chord with the root on the sixth string. To make it a 13th chord, I replace the fifth on the second string with the 13th two frets higher (see diagram 2B).
Once again, your assignment (or whatever you want to call it) is to experiment with the other chord shapes. Identify where the chord’s elevenths and thirteenths (or fourths and sixths) are and come up with your own “grips” for 11th and 13th chords, major, minor and dominant.