G blues scale
The blues scale is minor pentatonic with one note added: the flat five, D♭.
Six notes instead of five, and most of what sets it apart from minor pentatonic comes from that sixth one.
- How it sounds
- Darker and dirtier than minor pentatonic. The extra note sits between the 4th and the 5th, and a line that runs through it slurs and moans the way a singer would.
- Where it lives
- Blues, from Delta acoustic to Chicago electric, and everything that borrowed from it: blues-rock, hard rock, jazz and funk. Few players stay inside it for a whole solo. Most mix in notes from major pentatonic over the same chords.
Scale positions
- scale note
- blue note
- root
- High E string: F at fret 1, G at fret 3
- B string: C at fret 1, D♭ (blue note) at fret 2, D at fret 3
- G string: G at fret 0, B♭ at fret 3
- D string: D at fret 0, F at fret 3
- A string: B♭ at fret 1, C at fret 3
- Low E string: F at fret 1, G at fret 3
Notes and intervals
In order, with the frets between them: G3B♭2C1D♭1D3F2G
Home. Every other note is measured from it. F sits two frets below.
G
Perfect unison
Three frets up from G: minor third.
B♭
Minor third
Two frets up from B♭: whole step.
C
Perfect fourth
D♭: the blue note, six frets from home. Players slide through it far more often than they stop on it.
D♭
Diminished fifth
One fret up from D♭: half step.
D
Perfect fifth
Three frets up from D: minor third.
F
Minor seventh
The blue note
The added note sits exactly six frets above the root. That distance is the tritone, the interval that sounds least at rest. Pentatonic scales leave the tritone out, and the blues scale puts one back in.
The G blues scale on the low E string, from fret 3 to fret 15: G at fret 3, B♭ at fret 6, C at fret 8, D♭ at fret 9, the blue note, D at fret 10, F at fret 13, G at fret 15. The 4th, the blue note and the 5th sit a fret apart. The blue note is six frets above the root: the tritone.
It also creates the only place in the scale where three notes sit a fret apart: C, D♭, D. Everywhere else, neighbouring notes are at least two frets apart. Most of the scale’s slides and smears happen in that cluster, and the blue note usually gets slid through on the way from one neighbour to the other. Deep Purple’s “Smoke on the Water” riff is four notes of G blues: G, B♭, C, then G, B♭, D♭, C. The D♭ is the blue note, touched for a moment on the way to C.
Minor notes over major chords
Blues is played over dominant seventh chords, and those are major: G7 contains B, a major third. The scale has B♭, the minor third, one fret lower. Played together, the two rub.
G7 over the G blues scale. In both: G, D, F. Clashing, a fret apart: B♭ against B. Bent up a quarter tone, B♭ lands between the two, on no fret.
Most styles would hear that rub as a wrong note, and blues builds its sound on it. Guitarists often bend the B♭ up slightly, so it lands somewhere between B♭ and B: a pitch that isn’t on any fret. That in-between note is one of the most recognisable sounds in the style.
Notes over each chord
A blues rarely stays on one chord. The 12-bar form moves between three: G7, C7 and D7. The scale doesn’t change, but every note’s role does.
| Note | G7I7 | C7IV7 | D7V7 |
|---|---|---|---|
| G | R, fits the chord | 5, fits the chord | 11, colours it |
| B♭ | ♯9, tension | ♭7, fits the chord | ♭13, colours it |
| C | 11, colours it | R, fits the chord | ♭7, fits the chord |
| D♭ | ♯11, tension | ♭9, tension | 7, tension |
| D | 5, fits the chord | 9, colours it | R, fits the chord |
| F | ♭7, fits the chord | 11, colours it | ♯9, tension |
- fits the chord
- colours it
- tension
Step 1 of 3. Over G7, B♭ rubs against the chord’s B: the blues clash.
The home chord
G7 contains a tritone: B and F, six frets apart. Elsewhere that tritone pulls toward another chord and gets resolved. Blues treats the chord as home and leaves the tritone in place, so even the first bar sounds a little restless.
Blues progressions
Most blues follows one plan, the 12-bar blues: twelve bars, three chords. Four bars on G7, two on C7, two back on G7, then D7, C7, G7, and a final D7 that turns the form back to the start.
Three common variations:
- Quick change moves to C7 early, in bar 2.
- Minor blues builds the same plan on Gm7 and Cm7, with E♭7 and D7 in bars 9 and 10.
- 8-bar is a shorter form.
The major blues scale
Start the same six notes from B♭ and you get B♭ major blues: B♭ C D♭ D F G. Minor and major pentatonic share their notes the same way. Major blues sounds brighter, closer to country and early rock and roll.
The same six notes read from two homes. G blues: G, B♭, C, D♭, D, F. B♭ major blues: B♭, C, D♭, D, F, G.