Jazz Guitar Lessons
What To Know About Quartal Harmony and the Tritone Substitution
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In this lesson, JGT contributor Ivan Gygi discusses quartal harmony – with video and examples.
Sometimes the music we play calls for the colorful, outside sound of altered dominant harmony. The idea of using the tritones substitution to achieve this sound is often taught in the context of single line improvisations and comping with tertian harmony. In this lesson I will discuss how I apply this same concept with quartal harmony.
The first portion of this article is aimed for those who are not yet confident in their basic knowledge of quartal harmony. It is meant to be a brief study on its meaning and application that will prepare you for the following material. The second portion dives into the previously mentioned altered dominant application and the tritone substitution. If you are already comfortable with your quartal harmony fundamentals you can jump to this part.
What Is Quartal Harmony?
In contrast to traditional, tertian harmony which is built by stacking the notes of a scale in 3rds, quartal harmony is built by stacking 4ths.
Below is a fretboard diagram with the quartal harmony shapes derived from the C major scale. Practice playing these shapes in both 3 note and 4 note groupings.
While tertian harmony chords have a very specific sound and function, quartal harmony is a bit more ambiguous in nature. This ambiguity allows the quartal shapes to be applied in a modal context. What this means is that any of the shapes generated from the C major scale can be played over any harmony from the key of C.
Application
Quartal shapes are often used to create movement over modal/static harmony. Below is an example of shapes from the D dorian mode that could be used when comping on tunes like “Impressions,” or “So What.”
The same shapes can also be applied over a ii7 – V7 – I progression. When we do this we are harmonically generalizing the whole progression as being in the key of C major. Harmonic clarity comes when these shapes are combined with the root movement in the bass.
Inversions
Once you get a hang of the regular quartal shapes, a good way of getting new sounds is by using their inversions. These new structures help add variety and interest. A great example of these used in action is John Scofield’s comping on the record So Near So Far. Specifically, check out the track “Joshua”. Below I have included fretboard diagrams with these new shapes.
1st Inversion Shapes In C major
2nd Inversion Shapes in C major
There is a lot of educational material available on this topic of quartal harmony fundamentals. For a more comprehensive lesson on these introductory concepts, I recommend checking out Corey Christiansen’s Mel Bay video from the “In the Pocket Series”.
Continue with Quartal Harmony lesson >>>>
Quartal Harmony and the Altered Dominant Sound
Although playing the C major shapes over a ii7 – V7 – I progression sounds great, it only produces the unaltered notes in relation to the V7 chord. In jazz, the sound of the altered 7 is often desired for more colorful harmonic movement. I have two main methods that I like to use to achieve this sound. The first is by applying the quartal harmony shapes of the 7th mode of the melodic minor scale. This strategy is covered extensively in this JGT article by Zakk Jones:
Because I am more familiar with the major modes and their quartal shapes, I find I can usually be more creative when I use the tritone substitution to create the altered sound. With the rest of this article I will be discussing this second method, its uses, and applications.
Using the Tritone Substitution
If you are not familiar with the concept of the tritone sub, you can check out a great explanation from Chuck Anderson HERE.
Often when students learn about the tritone sub they are taught how to apply it within a single line or tertian harmony framework. When applied to quartal harmony, this concept creates some incredibly useful, altered voicings. Instead of using our C major / G mixolydian quartal shapes to outline a G7 chord, we will now use out Gb major / Db mixolydian quartal shapes. That gives us these notes in relation to the G bass note.
Our only problem note is the F#. Even though the major 7 shouldn’t theoretically sound good over a dominant chord, the strength of the quartal shapes and the tension created by the other notes allow it to work great!
When we encounter a ii7 – V7 – I progression, we can now approach it like this:
Rhythm Changes Etude
Below is a rhythm changes comping etude to help demonstrate the concept. Because the ii7 and V7 are interchangeable, when I encounter short ii7 – V7 progressions I often think of the whole measure as the V7 chord as shown in measures 16-20. I also like to occasionally treat the entire first four measures of the A sections as an altered dominant like in measures 41-43.
In these examples, I almost exclusively use quartal voicings. They are meant to show you how they can be employed over functional harmony to open things up sonically. When I am in actual performance situations, I tend to mix up the type of voicings I use a bit more. In many cases I even surround them with tertian harmony to disguise the intervallic sound. As you work out your own ways to blend your voicing types, you will develop your own unique style.