Altered Scale

Every alteration a dominant chord can take

A dominant seventh chord has two notes that fix its identity — the third and the flat seventh — and four that can be bent: the ninth, the eleventh and the thirteenth, each altered up or down. The altered scale contains the root, the third, the flat seventh, and all four alterations: ♭9, ♯9, ♯11 and ♭13.

Written that way the spelling makes more sense than the raw interval list. The ♭2 is the ♭9. The ♯2 is the ♯9. The ♯4 is the ♯11. The ♯5 is the ♭13. Nothing in the scale is unaltered except what the chord needs to stay a dominant, which is exactly why it fits over the chord symbol G7alt.

The sound follows from that. Everything in the scale is pulling somewhere, and none of the pulls resolve inside it — which is what makes it a scale for the chord before the resolution, not for the resolution itself.

Super Locrian: the same scale under another name

Both names describe one set of notes. Super Locrian counts from the interval structure: the Locrian mode already lowers everything a seven-note mode can lower, and this scale lowers the fourth as well, so it is Locrian taken one step further. Altered counts from the chord it serves.

Which name a source uses tells you where it came from. Classical and academic modal theory tends to say super Locrian; jazz method books and chord charts say altered, because that is how it appears above the staff. Neither is more correct, and mixing them in one sentence — altered super Locrian — is redundant rather than more precise.

One further name worth recognising is diminished whole tone, which describes the shape: the lower half moves in semitone-and-tone steps like a diminished scale, the upper half in whole tones. Same notes again.

The half-step-up shortcut on guitar

Nobody memorises the altered scale as its own pattern. The working method is one sentence: over a dominant chord, play melodic minor a semitone above its root. Over G7alt, play A♭ melodic minor. That is the entire trick, and it is why learning melodic minor in five positions is worth more than learning any of its modes separately.

Check it against the chord and the arithmetic holds: A♭ melodic minor is A♭ B♭ C♭ D♭ E♭ F G, which spelled from G is G, A♭, B♭, C♭, D♭, E♭, F — root, ♭9, ♯9, 3, ♯11, ♭13, ♭7. Every alteration, nothing missing, nothing extra.

The practical caution is about resolution rather than fingering. The scale is tense by construction, so it works over the dominant and stops working the moment the chord changes. Guitarists who like the sound tend to hold it a beat too long; landing on a chord tone of the target chord is what makes the tension read as intentional.

Where it is actually used

The standard home is the dominant chord in a minor two-five-one: Bm7♭5, E7alt, Am. The altered scale over the E7 gives the maximum tension available before the resolution, and because the target is minor, the ♭13 and ♭9 lead into it naturally.

It also works over dominants resolving to major, where the effect is sharper and needs more care — the ♯9 against a major target is the sound of a great deal of post-bop, and it is a choice rather than a default. Over a static dominant with no resolution coming, the scale tends to sound like an exercise, for the same reason harmonic minor does over a tonic minor chord.

Beyond jazz the scale appears wherever a dominant chord is pushed hard: fusion, some film scoring, and in metal through its overlap with the diminished sound. What it does not do is function as a general-purpose scale — every note in it is defined by the chord underneath, and without that chord the alterations have nothing to be altered against.

Frequently asked questions