The A blues scale on guitar
Minor pentatonic plus the ♭5 passing note — what the blue note does, and why you move through it rather than sit on it.
- Notes
- A · C · D · E♭ · E · G
- Formula
- 1 · ♭3 · 4 · ♭5 · 5 · ♭7
- Notes in the scale
- 6
The blues scale is minor pentatonic with one note added: the ♭5, E♭ in the key of A. That single note is responsible for most of what people describe as grit or tension in a blues line. It is a chromatic passing tone squeezed between the 4th and the 5th, and it does its work in motion.
Hold it and the line stops sounding bluesy and starts sounding wrong. That is not a failure of taste on your part; it is a fact about the harmony, and the section below spells out why.
A useful discipline while learning it: play a phrase using only minor pentatonic, then play the same phrase again and let the ♭5 appear exactly once. That is roughly the ratio you want.
Where it sits on the neck
There is no new shape to learn. The positions are the minor pentatonic positions, and the ♭5 is a dot added to each of them.
In box 1 at the 5th fret it appears twice. The first is the 6th fret of the A string, sitting between the 4th at the 5th fret and the 5th at the 7th — three consecutive frets under three consecutive fingers, which is why that is the one to learn first. The second is the 8th fret of the G string. On that string the 5th above it is at the 9th fret, outside the four-fret window, so approach that one from below and come straight back down rather than trying to continue upward.
- Root on the A string — the open strings to the 3rd fret.
- Root on the G string — the 2nd fret to the 5th.
- Root on the low E string — the 5th fret to the 8th.
- Root on the D string — the 7th fret to the 10th.
- Root on the B string — the 10th fret to the 13th.
What to play it over
Everything a blues in A throws at you, on one condition: keep moving through the E♭.
Look at what that note is against each chord and the condition explains itself. Against the A7 it is the ♭5. Against the D7 it is the ♭9. Against the E7 it is the major 7th. Three chords, three dissonances, and no bar of the form where it has anywhere to rest. That is not a flaw in the scale, it is the job description — the ♭5 is interesting precisely because it belongs to nothing.
The other five notes are ordinary minor pentatonic and behave exactly as they do there, so nothing else about your note choice has to change when you add it.
The common mistake
Learning it as a six-note shape and then running the shape. The moment the ♭5 is just the next dot in the pattern it arrives because your fingers got there rather than because you meant it, and what a listener hears is an ascending scale with a wrong note in it. Add it to phrases you already play instead, one at a time, so it is always a decision. If you cannot leave it out on the next repeat, you have not learned the note — you have learned a fingering that happens to contain it.
Licks to add it to
None of the licks below contain the ♭5, which is deliberate. It is a note you add to vocabulary you already have rather than vocabulary of its own.