Yngwie uses a flexible approach to the minor key, similar to the way it’s used by classical composers. It’s probably better to not think of Harmonic vs. Melodic vs. Natural Minor as 3 different scales, but as 3 different hues of the same tone color. All three of these scales use 5 out of 7 identical intervals, but there’s a chromatic alteration of 1 or 2 notes: +7 for Harmonic minor, +6 & +7 for Melodic minor. This doesn’t radically alter the tonality of the key, but it creates a stronger feeling of melodic tension that resolves to the tonal center (the root or octave).
As a rule of thumb, the raised notes occur in ascending melodic moves, while natural notes occur in descending moves. However, Yngwie often combines the natural and sharp 7 in the same run, sometimes right next to each other as chromatic passing tones. The natural and altered tones are “stacked” on top of each other and used to color the expression as needed.
It’s the same kind of thing with the “Blues Scale”. It’s just a minor pentatonic with a chromatic passing tone between 4 & 5. There’s no real change in tonality, just a slightly different flavor.
The Phrygian mode is the 5th mode of Minor. In the Key of A minor, the 5th mode is E Phrygian. This mode is similar to Aeolian/Natural minor, except it has a minor/flat 2 or 9 interval.
Phrygian Dominant is the 5th mode of Harmonic Minor. The major/sharp 7 in Harmonic minor is the 3rd of the Phrygian Dominant mode, so this is a Phrygian scale with a Major 3. This is why Yngwie uses it over the Major V chord in minor, because the major 3 in the chord aligns with the major 3 in the scale.
If that seems over complicated, just know that you can play all the notes of A harmonic minor over an E major or E7 chord, and that’s the sound of the Phrygian Dominant mode. It relates to what’s happening harmonically or in the bass.
The Diminished 7 chord has a cool relationship with harmonic minor. It’s the ‘natural’ VII chord (the chord build on the 7th step of harmonic minor). Dim 7 is a symmetric chord: all the intervals are minor 3rds stacked on each other. It also has 2 tritones stacked a minor 3rd away. This means it doesn’t have a true root, any of the notes in the arpeggio can be the “root”.
This makes it really flexible, like a ‘wild card’ that fits in multiple keys. It’s typically used as an altered dominant chord, which means that anywhere there’s a dominant or V chord in the progression, you can use it as a leading or passing chord.
In A minor, the G# Dim7 chord acts as a V chord into I: A minor, or as an altered dominant over E7 - the I chord in Phrygian Dominant.
The “Stacked” Dim7 chords are just the inversions of the same chord: G#dim7 - Bdim7 - Ddim7 - Fdim7 are all the same notes and identical harmony.
- More on Chord Scale relationships
In the Natural Minor scale, the V chord is a minor triad or minor 7. Traditionally, classical composers found that substituting a major triad or dominant 7 chord created a more powerful resolution into the I chord. This is a simple chromatic alteration, raising the 3rd of the V chord up a 1/2 step from minor to major. The 3rd of the V chord is the same note as the 7 in the key - this is the same alteration we find in Harmonic Minor (+7) and Phrygian Dominant (+3).
So in a nutshell, any time there’s a progression using Major V (or Dominant V7) to Minor I - Yngwie is almost always using the Harmonic Minor/Phrygian Dominant over the V, and sometimes over the I.
Essentially, you have freedom to use natural or altered minor over the I chord, but use the altered notes on the V chord.
I’m not sure how Yngwie really thinks about this stuff, I don’t get the impression he’s super analytical about his playing or theory behind it lol. Play Loud!