The blues scale on guitar: one note more than the pentatonic

The blues scale is the smallest extension in this whole cluster, one single note more than the minor pentatonic. No new shape, no new hand position, two extra dots per position. If you can play the pentatonic, this article is a practice session’s worth of work.

Which is exactly why it comes last in this cluster’s order. Without the minor pentatonic underneath, it is a six-note scale with an odd note in it. With the pentatonic underneath, it is a tool.

The one added note

To the minor pentatonic A, C, D, E, G the flat fifth is added, which in A is E flat. Six notes in total: A, C, D, E flat, E, G.

Degree	Note in A	Interval	Frets above the root
1	A	root	0
♭3	C	minor third	3
4	D	fourth	5
♭5	E flat	flat fifth	6
5	E	fifth	7
♭7	G	minor seventh	10

The new note sits between the fourth and the fifth, in the gap that was three frets wide in the pentatonic. That puts it six frets above the root, exactly halfway through the octave. The interval is also called a tritone, and it is the only one that is the same distance from the root going up as going down.

It is called the blue note, and it is the best known of several. The minor third and the minor seventh count as blue notes too, because both are lowered relative to the major scale. When a method book says the blue note, though, this is usually the one it means.

Why it only works in passing

The flat fifth is the one note of this scale you cannot stop on. It is loaded with tension and wants to move, in either of two directions: one fret up to the fifth or one fret down to the fourth. Both sound right. Staying sounds like a wrong note.

Taste has nothing to do with it; the reason is where the note sits. It is a half step from both of its neighbours, and both neighbours are stable notes of the scale. A note wedged between two stable ones is heard as a passing tone, not as a destination.

In practice: in a slow blues, one blue note per phrase is usually enough. A string of them does not sound bluesier, it sounds undecided. The effect lives on being rare.

Position 1: frets 5 to 8

Compare this with position 1 of the minor pentatonic and you find exactly two new dots: on the A string at the sixth fret and on the G string at the eighth. Everything else is unchanged.

Both sit right next to a note you are already fretting. On the A string the index finger slides up one fret from the D at the fifth. On the G string the little finger joins one fret above the ring finger. The A string therefore carries three notes in three consecutive frets, D, E flat and E, and that is where the blues feel of this position lives: up to the E flat, on to the E, and back again.

Position 2: frets 7 to 10

In position 2 the blue note occurs only once, on the G string at the eighth fret. There it stands between the D at the seventh and the E at the ninth, which is precisely the arrangement described above: three notes, three neighbouring frets, the middle one is the passing tone.

A position having only one blue note is not a shortcoming. In this region the G string is where most blues licks happen, and that is why.

Every blue note on the neck

In the first twelve frets each string carries exactly one blue note: on the low E string at the eleventh fret, on the A string at the sixth, on the D string at the first, on the G string at the eighth, on the B string at the fourth and on the high E string at the eleventh again. Six places, and once you know them you find them in any position without searching the shape.

Moving it into any key

As with the pentatonic, the root of position 1 sits on the low E string and the position starts there.

Key	Root on the low E string	Position 1 spans
E blues	fret 0 (open) or 12	0–3 or 12–15
G blues	fret 3	3–6
A blues	fret 5	5–8
C blues	fret 8	8–11
D blues	fret 10	10–13

A and E are the two blues keys most played, because on a guitar they have the low open strings as their root.

Why minor works over a major backing

Here is the point where the blues differs from everything else in this cluster, and it confuses everyone who notices it for the first time.

A blues in A is usually played over A7, D7 and E7. Those are dominant seventh chords, and each of them contains a major third. In A7 that is C sharp. The blues scale you play over it, however, contains the minor third, so C. Two notes one fret apart, sounding at the same time.

By the rules that otherwise govern major and minor, that should not work. In the blues, this friction is the sound. It is not tolerated, it is the reason the music is called what it is. Two consequences for practice:

1. You do not have to change scale when the backing changes chord. The same A blues scale works over A7, D7 and E7 throughout, which makes a blues the most forgiving form to improvise over.
2. The minor third is itself a blue note. What was said about the flat fifth applies to it in a milder form: it sounds best in motion, often as a move from C towards C sharp, which guitarists play as a half-step bend.

Three exercises

1. The blue note in passing only. Play position 1 up and down and take the two new dots with you without lingering on them. Eighths at 70 bpm are enough. The aim is for your hand to include them without you thinking about it.
2. Four notes and a rest. Build phrases of at most four notes, at most one of them a blue note, then leave a whole bar of silence. This is the exercise that turns the scale into blues, and it is harder than it sounds.
3. Over a major backing. Record twelve bars of A7, D7, E7 or find a play-along, and use position 1 only. Listen for the moment the C of the scale meets the C sharp of the chord. Once you have consciously heard that friction, you play it on purpose from then on.

Three mistakes

1. Stopping on the blue note. The most common one, and it sounds like a mistake rather than like blues straight away. Move on, in either direction.
2. Putting it in every phrase. One per phrase is plenty. The note works because it is rare.
3. Learning the blues scale before the pentatonic. It is an extension, not a scale in its own right. Without the five positions underneath, the thing being extended is missing.

What comes next

That completes the four scales of this cluster. The next step is not a fifth one but breadth: the five positions of the minor pentatonic across the whole neck, each of which gets the same two extra dots once you know it. How all four relate is in the overview.

How positions, chord shapes and scales slot into each other on the fretboard is covered in the tutorial on the fretboard module; in the module itself you can switch between pentatonic and blues over one and the same position. Everything else about the module is in the feature overview.