altWhen I was learning scales the altered scale was always sort of an enigma, possibly because of its ominous name or unfamiliar shape to me. I always feel slightly irked when certain scales are referred to as ‘exotic’ as the altered scale sometimes is (wrongly, in my opinion).

Common in jazz, but also pop and in some more modern classical and Romantic period music, the altered scale is a mode of the melodic minor (modes will be covered later – definitely worth getting up to speed if you’re not). Its sound is dominant, as it contains major third and flattened seventh degrees, however the rest of the degrees are all altered.

The melodic minor is really two scales with ascending and descending variations, but for simplicity I’ll nearly always be referring to the ascending version. Check out what I mean here.

Certain people apparently refer to it as the ‘Super-Locrian mode’ or some waffle but I’ve not met any of them and, seeing as the Locrian mode is painfully difficult to compose with, the altered seems more befitting to me.

Altered Beast

To understand why it’s called ‘altered’ is really quite simple, but first let’s look at a simple C major scale:

c maj

This contains the notes C, D, E, F, G, A, B and C. Each degree is of the scale is ‘natural’ when our key signature is C major (no sharps or flats). In contrast, the altered scale literally ‘alters’ each degree by flattening it:

c alt

This contains the notes C, Db, Eb, Fb, Gb, Ab, Bb and C (fig.1) however some might prefer to understand this as C, Db, D#, E, F#, G#, Bb and C (fig. 2).

Fig. 1 is how the scale reads enharmonically (read up on enharmonic equivalents here), but fig. 2 is how I tend to remember the degrees. What’s really important is what’s easier for you to understand the scale. [However, if you’re in an exam it’s more important to understand what’s technically correct, which is fig. 1!]

In the example of C, an easy way to get your fingers around the scale is just playing a B major scale, with the Bs replaced with Cs. The tones are as follows, with the alternatives in brackets:


Flat 2nd

Flat 3rd (or minor 3rd)

Flat 4th (or major 3rd)

Flat 5th (or sharp 4th, commonly referred to as sharp 11).

Flat 6th (or sharp 5th)

Flat 7th

How to Use the Scale

The altered scale is most commonly used over a V chord leading to the I. For example, using a ii, V, I chord progression in the key of C major (D-, G7, C) the G altered scale would be used over the G7 chord.

Some chords that can be extrapolated from the scale are below:

In fig. 3, the chord is could be looked at as a C7 shell (C, E, Bb) with a Db (b9) and F# (#11) on top of it. Another way to understand this would be C and E at the bottom of the chord with an F# 1st inversion chord in the top of the chord (A#, C#, F#).

In fig. 4, chord is a C+7(#9) which contains both an E and D# making it technically neither major nor minor. The Bb, Eb and G# is a series of fourths; if your hand can reach, the next fourth up would be the Db.

Finally in fig. 5, I would describe this this chord as an F#/C . Notice it contains the same notes as our first chord, how you would write it would depend on context and function; e.g as a V in F minor, I would write C7(b9, #11), however as a V in B or B minor, F#/C would make more sense.

Unless there is a specific need for a particular voicing (like an F# in the melody or a combination of notes that gives the correct chordal colour) then we often see ‘C alt.’ written, giving the accompanist the option to choose their own voicing. Often when transcribing in a rehearsal or writing environment I too will use C alt for speed but it’s entirely down to you what you write.


The altered scale can function as a great starting point for writing or soloing over dominant chords in major or minor keys. In addition, if you’re confronted by a chord with any of these extensions in, the altered scale is a handy mode to turn to and can add great sophistication and interest and when composing, the chord oozes tension and works well as a standard V chord.

I’d be interested to hear your thoughts or answer any questions.


  • lee says:


    Altered C is also the key of Gb (or F#) played to a sharp Lydian (or flat Mixolydian (5th)).

    Blues scales add a Vb, & I’d be curious to see in practice if accidental augmentations of the tonic don’t show up in altered scales….

    • alijamieson says:

      Hi Lee

      That’s absolutely correct, but I avoided mentioning the Lydian Dominant mode as I find it can confuse people. For example, when you see a C7 chord, thinking a mode of the Gb Lydian Dominant scale isn’t the most economic though process to me.

      I also have something on tritone substitutions that will be published soon, and I will cover the relationship of these in more depth there.

      I don’t follow the last thing you mentioned ‘Blues scales add a Vb…’ can you elaborate?


  • lee says:

    Maybe note significant, just the overlap with the flat fifth that’s added to the Blues pentatonic (sexatonic? ).

    Modes always to me begged the question key vs. mode. Weird key, or functional mode?

    • alijamieson says:

      For the altered scale, I wouldn’t ordinarily think of this as a modal approach, as it’s just a great scale for a V chord, where as I tend to view a modal approach as a wider way of viewing a song.

      I’m not familiar with the sexatonic, but I think whatever suits you best is the best way to approach the song.

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