Stacked 4ths and the “So What” chord

Our previous studies have been focused on chords built by thirds. Triads and 7th chords serve as our basic and most useful harmonic building blocks.

Here we will be using the practice of walking a chord shape though a major key, though instead of using stacked 3rds, we will experiment with intervals of stacked 4ths.

This chord voicing has a few particularities. There are three dissonant intervals embedded in the chord, the major 7th between C and B, the augmented 4th between F and B, and another major 7th between F and E. All together, these four notes create a rather opaque sounding C major chord.

Now, let’s try walking this chord shape though the key of C major.

Now, let’s try this in the keys of G and F.

The resulting chords do not posses the same harmonic clarity of the previous studies, though the cloudy effect is nonetheless beautiful. These sounds are common jazz vernacular, typically associated with 60’s modal jazz:

The same chords can also be heard in the 3rd movement of Respighi’s “The Pines of Rome”

And by stacking a major 3rd on the top of this voicing, we create the famous “So What” chord.

To do this, we will start with a stack of 4th, projecting up from E. To this, we will add a B on top. This entire chord shape will simply all move down by one step:

Now, in time, with the bass line:

The “B” section of “So What” is simply the “A” section transposed up a half step. The chords for “B” are:

And with the bass: