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I was looking up info on scales today and found this page on scales: http://en.wikipedia.org/wiki/List_of_musical_scales_and_modes

Scrolling through the page, I found a few interesting scales, but one caught my eye. The Prometheus scale looked like the Mixolyidan with an augmented 4th or Lydian with a minor 7th. I tried to find out more information about it, but the only thing I found was it was used to harmonically describe some of Alexander Scriabin's later work. It looks like it would make a very interesting scale for composition, but how can someone use this scale in a piece?

  • I'm not sure I understand what an answer would be to "How can someone use this scale in a piece?" – LiberalArtist Sep 1 '14 at 3:25
  • @LiberalArtist every scale/mode has it's own flavors of harmony, melody, chord progressions, and nuances. How someone would write a song in a major key is different then how it will be written in minor, mixolydian, lydian, ect. I expect this scale to also be used differently. – Dom Sep 1 '14 at 4:50
  • Note that the Prometheus scale is a hexatonic scale and is not identical to the mixo#11/lydian dominant scale because it misses the 5th scale degree. However, all notes in the Prometheus scale are also included in the more common (at least in Jazz) mixo#11/lydian dominant scale. – Matt L. Sep 1 '14 at 6:54
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Of course there are infinite ways one might explore a scale or harmony compositionally, but one aspect of the pitch collection that made it interesting to Scriabin is that it can be used to resolve in a more-or-less traditional manner to a number of different distantly related harmonic areas.

First off, a reminder about the harmonic possibilities of a standard dominant seventh chord (and let's leave out the fifth of the seventh chord for reasons that will become evident later). Say we have C, E and Bb. This could be a C7 chord, which implies a tonal resolution to F. The most important melodic driver of that resolution is the tritone between E and Bb, which wants to collapse (or expand if written as an augmented fourth) into F and A. Of course, any tritone can be enharmonically reimagined. In this case, we could also see it as E and A#. This tritone wants to expand (or collapse if written as a diminished fifth) into B and D#. Thus E and Bb/A# could either be used for a melodic resolution to F or to B which is a tritone away and as far apart as any two major keys can be.

But the C7 harmony we were discussing also has a harmonic reason to resolve to F--the movement of a fifth/fourth from C to F. We could use it to resolve to B, but it wouldn't be as convincing in tonal terms. The notes E and A# would need a root below them that could turn the harmony into a dominant seventh (with a missing fifth). That note would be F#, giving us F#7--F#, A# and E. If you look at the Prometheus scale, you'll see that it also has F#, so a composer is able to construct either C7 or F#7 just as easily. Furthermore, the entire collection played as a harmony--Scriabin's so-called "mystic chord"--has equal potential to resolve in either direction.

Notice however, that the two roots C and F# are also a tritone apart from each other, and thus could be used to melodically resolve to G or (with enharmonic respelling of F# as Gb) to Db. The first of these possibilities is further strengthened by the presence of D and A in the chord, which could be heard as the root and fifth of a D7 chord--D, F#, A and C. When used as a harmony, the chord has equally clear tonal possibilities to resolve in F, B or G, making it into a sort of asymmetric three-tonic system.

This kind of ever-shifting quality is common in a lot of Scriabin's music, which often sounds surprisingly tonal despite some very dense harmonies and unorthodox connections. Scriabin also used the collection as source material for other harmonic sets and melodic figurations. Its prime form is (013579), and a lot of interesting harmonies can be picked out of it. It's almost, but not quite, symmetric (essentially a whole tone scale with one note altered), and that means that it has many transpositions and inversions that will retain several common tones. This can be useful for creating transitions and connections between different harmonic instantiations. However, because it isn't truly symmetric, no transposition creates the same harmony exactly, there will always be at least one different pitch, which allows for greater variety. A deeply interesting pitch collection.

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The notes from the Lydian dominant, containing a b7 and a #4 (#11) work over the dominant chords, as in 7th, 9th and 13ths. As with any scale with a #4 - plain Lydian is an example - that actual note gives a dissonance to the phrase it's used in, therefore needs to be used with care. This gives a feeling of tension, sometimes almost signalling a modulation to the dominant of a key, without actually going there.

It's the fourth mode of the melodic minor, used in jazz, and blues a lot.

That #4 can have the same effect as the b5 found in blues, even if it's technically not the same note.

  • I thought that it was the fourth mode of the melodic minor as well, but the Prometheus scale doesn't have a 5th, whereas the former one does – Shevliaskovic Sep 1 '14 at 7:21
  • @Shev - you're right. Prometheus =Lydian dominant -minus the perfect fifth. The OP mentions both, so I thought I'd put my tuppence-worth in. Suppose one writes a piece in a major key. Is there a compunction to use every single note available ?... – Tim Sep 1 '14 at 7:28
  • You got a point there – Shevliaskovic Sep 1 '14 at 7:40

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