Quartal-ish Chords from Yagapriya

Just a quick follow-up to my previous post about Yagapriya. We start with the 4-8 chord inside Yagapriya, which isn't quartal, and end up developing a little world of quartal-like harmony from it.

Recall that we're studying C Yagapriya (C-D#-E-F-G-G#-A) and the 4-8 chord it contains is E-A-D#-G#. This 4-8 chord is a subset of the E major scale (E-F#-G#-A-B-C#-D#). So these two seemingly very different scales share 4 out of 7 of their notes.

Letting the two scales play off against each other -- for example, alternating between them over a C drone -- is sour and discombobulating. Yagapriya is already dissonant and awkward with its lumpy collection of intervals and the lack of much in the way of triadic harmony we observed in the earlier post.

Even worse, E major over C offers very little respite from dissonance -- its notes relative to C are, respectively, a major third, a flat fifth, a sharp fifth, a sixth, a major seventh, a flat nine and a sharp nine. It ought to be an "altered major seventh" sound but the natural six, and of course the absence of a root note, makes it hard to wrangle into jazz language.

The notes they don't share are C-F-G in C Yagapriya vs C#-F#-B in E Major. Re-ordering them reveals that these are both "pure" quartal chords: G-C-F and C#-F#-B are both stacks of perfect fourths. I'm going to call this the "quartal triad" here. And although 4-8 itself isn't quartal, we can see it as a pair of fourths (B-E and C-F) and it really does have a quartal flavour (at least in some voicings).

If we visualise the 4-8 at the root, here's how they fit into it (Adding the red notes makes a major scale, adding the blue notes makes a mode of Yagapriya):

The first thing that struck me is that there are two more ways to add our little quartal triad to 4-8. The green one gives us modes of Kamavardani / Kanagangi and the purple one yields modes of Chalanata / Shubhapantuvarali:

All of these have a very modern bluesy-modal-jazz kind of vibe that I think is very approachable. Since there's a similarity of sound to them I'm inclined to see them as a "system" of variations on a single overall theme.

This might lead us to look at combinations of pairs of the quartal triad. With the 4-8 as in the diagrams above (i.e. 1-3-4-7) the quartal triads are:

• Red: b2-b3-b6
• Blue: 2-5-6
• Green: b3-b7-b6
• Purple: b2-b5-b6

Pairing them up produces three essentially different results:

• R + B: b2-2-b5-5-b6-6 (6-z38)
• B + P: b2-2-b5-5-b6-6 (6-z38, same as R + B)
• B + G: 2-b3-5-b6-6-b7 (6-z38, Same as R + B a semitone higher)
• R + G: b2-b3-b6-b7 (4-23)
• R + P: b2-b3-b5-b6 (4-23, same as R + G a fifth higher)
• G + P: b2-b3-b5-b6-b7 (common pentatonic)

6-z38 is a very chromatic hexatonic that might be worth exploring in connection with the Lulu chord it contains but isn't very promising on its own. 4-23 is the stack of four fourths, which isn't a very surprising thing to find. The common pentatonic might seem surprising but not really -- it's just the "black notes" to the corresponding "white notes" of the major scale we found earlier. It's also a stack of five fourths, which you can also get by combining the two copies of 4-23.

I think, excluding 6-z38, these are easy enough to think about: the sound comes from playing 4-8, a major scale subset, and mixing the notes from that major scale's complement (common pentatonic) with the three other notes that live in the major scale but aren't in 4-8. All these are rather "fourths-ful" so even when they don't yield actual quartal harmony they do have some of that going on. I think this might be an interesting new spice to cook with (I'll come back to 6-z38 in a future post).