The altered scale on bass:
notes, formula and position

The altered scale has 7 notes: 1 ♭2 ♭3 ♭4 ♭5 ♭6 ♭7. In A, that gives A, B♭, C, D♭, E♭, F and G. The 7th mode of melodic minor: every altered tension of a seventh chord (♭9, ♯9, ♯11, ♭13). It is the scale of the 7alt chord, just before the resolution.

Also called: Super Locrian, mode VII of melodic minor.

Formula and notes

1 ♭2 ♭3 ♭4 ♭5 ♭6 ♭7

The steps between the notes, from the root to the octave: half step – whole step – half step – whole step – whole step – whole step – whole step. In A:

Where the altered scale comes from

It is the 7th mode of melodic minor: you play the notes of melodic minor starting from its 7th degree. The altered scale in A therefore has the same notes as B♭ melodic minor. What changes is the home note: the root A, the note your line keeps coming back to.

One position on the neck

The altered scale in A, in the 5th-fret position: one finger per fret, from the 4th to the 8th fret, on all four strings. The numbers are the degrees; the root is in gold.

The same position as bass tab (fret by fret, from the low E string to the G string):

G|-5--6--8-|
D|-5--7--8-|
A|-4--6--8-|
E|-5--6--8-|

For another key, move the whole shape: the root on the E string sets the key (3rd fret for G, 8th fret for C).

The sound of the altered scale

7th mode. All altered tensions. Altered scale. THE scale for altered 7 chords: over the chord, ♭9, ♯9, ♯11 and ♭13.

You mostly hear it in jazz and fusion.

Which chords to play it over

In A, the altered scale fits A7alt and A7♯9♭13. On bass, keep the root on the strong beats and use the other notes to connect the chords.

Neighbouring scales

These scales differ from the altered scale by a single note. Comparing them lets you hear exactly what that note brings.

• The Locrian mode: 4 instead of ♭4.
• The Ultralocrian mode: 𝄫7 instead of ♭7.
• The enigmatic scale: 7 instead of ♭3.

Practice it with UnitBasse

This diagram shows a single position, in a single key. In UnitBasse, this scale is shown across the whole neck and in all twelve keys, as note names, intervals or degrees, with one color per degree. You can listen to it, see the chords that go with it, switch keys in one click, and play it over a chord chart with BackTrack, the app’s backing band. The app has 69 scales in 12 families.

Frequently asked questions