(Some of) The Many Applications of Forte 4-3

This little cluster of four notes can expand your vocabulary and open the door to exotic scales and chords, including both conventional jazz stuff and more far-out weirdness. I find this especially useful for finding things on piano (which I'm not very good at) but it applies to anything really.

The four notes I mean are Forte 4-3, which could be written C-C#-D#-E. In other words, it's a semitone, a tone and a semitone. I think of this as a little cell that I can play in various positions to get a variety of sounds.

Since the gap between its end (E) and its next beginning (C an octave up) is large, there's room to fill it with various interesting things. Over any given root note we can start Forte 4-3 in any of 12 places, and fill in the remaining gap with any of the 35 ways to choose 3 notes from the 7 in the gap. Some of these will turn out the same, of course, and we might also want to remove the combinations that don't give us a root note, but that still leaves a lot of possibilities. Even more are possible if we want more or less than seven notes, but that will be enough to keep us busy.

Filling the Gap with Whole Tones

The simplest thing to fill that gap with is whole tones, giving us the scale C-C#-D#-E-F#-G#-A#. This is the famous Altered Scale, which you probably know is a mode of Melodic Minor.

We get all the modes of this scale from 4-3 as follows:

  • 4-3 starting at the root: Altered Scale, works over altered dominant chords
  • 4-3 starting at the 2: Half-Diminished Scale (a.k.a. Locrian Natural 9), works over m7b5 chords
  • 4-3 starting at the major third: Mixolydian b13 Scale, works over "plain" dominant chords
  • 4-3 starting at the #4: Lydian Dominant Scale, works over 7#11 chords
  • 4-3 starting at the #5: Lydian Augmented Scale, works over major 7 chords (with caution!)
  • 4-3 starting at the 6: Dorian b9 Scale, works over minor 7 chords (with caution!)
  • 4-3 at the major 7: Melodic Minor Scale, works over m6 or tonic minor chords

If you don't already know these scales, practice them by playing the chord and finding the appropriate 4-3 to go with it. Notice that each mode works with a different type of chord, so simply by associating the "correct" 4-3 with it, you'll pretty much learn all the Melodic Minor modes at once. Of course this isn't a "hack" that removes the need for practice, but it's a quick way to get off the page and start internalizing these sounds.

Filling the Gap with a Diminished Triad

The only triad that fits into the gap is the diminished triad F-Ab-B, giving the scale C-C#-D#-E-F-Ab-B. This is a mode of Yagapriya and is rather exotic.

You'll notice, if you play it, that it's really a sort of "super-4-3" in the sense that you get an extra note a semitone above and below the 4-3, making for quite a collision of semitones with the comparatively airy diminished triad spacing it out. The diminished triad expends to a m7b5 thanks to borrowing a note from the 4-3; I tend to think in terms of seventh chords more than triads so this is helpful for me.

If you can "see" the relationship between the m7b5 and the 4-3, you only need to "find" one of them, but I'm undecided which works best for me -- I suspect it's the 4-3 on piano but the m7b5 on guitar, so I'll mention both. Many of these are lovely sounds that should be better-known:

  • 4-3 at the 5, m7b5 at the root: Susdim Dominant -- a mysterious, dark minor sound.
  • 4-3 at the 3, m7b5 at the 6: Yagapriya -- bluesy sound on a m6 chord.
  • 4-3 at the b2, m7b5 at the b5: 2maj + 4maj -- a tough one to love, although Cmaj7 / Dmaj7 / Fmaj 7 has a nice neo-soul kind of vibe to it so there might be something there.
  • 4-3 at the root, m7b5 at the 4: b2maj + 3maj -- nice and crunchy on a major 7 chord.
  • 4-3 at the 7, m7b5 at the 3: Varunapriya b4 -- a cool "Lydian dominant" type of sound.
  • 4-3 at the 6, m7b5 at the 2: Vanaspati #5 -- more of an "altered dominant" sound, but it has a natural 9 so it hits that Whole Tone sweet spot of being sort-of altered and sort-of not. Will cause you to fail Jazz 201.
  • 4-3 at the #5, m7b5 at the b2: Phrygian Semiaugmented -- a sour major 7 sound.

Filling the Gap with a "Minor Trichord"

What I mean by a "minor trichord" (MT here) is a whole tone followed by a semitone, which is the first three notes of the commonest minor scales (Natural Minor, Melodic Minor and Harmonic Minor). There are four ways to place it inside the gap left by 4-3; one is common and useful, two are very exotic and one is uncommon but turns out not to be useful.

The only one I think is worth your time is the one that yields modes of Harmonic Minor -- it's a fresh way to approach these, or maybe even a way to learn them if you don't already know them:

  • 4-3 at the 7, MT at the 4: Harmonic Minor
  • 4-3 at the 6, MT at the b3: Locrian Nat 6
  • 4-3 at the #5, MT at the 2: Augmented
  • 4-3 at the #4, MT at the root: Dorian #4
  • 4-3 at the 3, MT at the b7: Phrygian Dominant
  • 4-3 at the b3, MT at the 6: Lydian #9
  • 4-3 at the 1, MT at the b5: Super Locrian bb7

Of these I think Dorian #4 and Lydian #9 are lovely scales, but Phrygian Dominant and Harmonic Minor itself are the ones you hear most often.

The very exotic ones come from 4-3 at the root and the MT at either the 4 (i.e. F-G-Ab) or #5 (i.e. G#-A#-B), the lowest and highest of the four possibilities. The first of these is just called "5maj + b6maj" in the scale book; the second is the Eurean scale, part of a set I whimsically named after the eight winds of Greek mythology. They are far-out and interesting to explore but perhaps not things you want to memorize.

Meanwhile, 4-3 at the root and MT at the fifth gives a mode of the scale I call Marva Dominant. This is an unusual scale that sounds good but it's just seven of the eight notes of the Half-Whole Diminished scale, so it's probably not worth learning as a thing in itself.

Filling the Gap with a "Phrygian Trichord"

By this I mean, of course, the first three notes of the Phrygian scale, i.e. a semitone followed by a tone or C-Db-Eb. I'll write it as PT. The story here is very similar -- two highly exotic scales, one that's just a diminished scale with a note missing, and another that's actually useful.

The useful one gives us the modes of harmonic Major. It's worth giving some time to this one if you don't already know it; the modes are full of pretty and unusual sounds:

  • 4-3 at the 7, PT at the #4: Dharmavati (aka Lydian Minor)
  • 4-3 at the 6, PT at the 3: Chakravakam (aka Mixolydian b9)
  • 4-3 at the #5, PT at the b3: Kosalam #5
  • 4-3 at the 4, PT at the 1: Locrian bb7
  • 4-3 at the 3, PT at the 7: Harmonic Major (aka Sarasangi)
  • 4-3 at the 2, PT at the 6: Dorian b5
  • 4-3 at the 1, PT at the 5: Phrygian b4

Well, these are interesting ways to learn some seven-note scales in modal groups. But the technique also points towards a "post-scalar" approach to material like this, in which we put together melodic lines and phrases from small fragments. This has a long historical pedigree but I don't think modern improvisers often think about it consciously -- I might be wrong about that, of course.