The blues: 12-bar form and blues scale

The blues is the root of rock 'n' roll, hard rock and heavy metal. Learning its form and its sound will make you a better player in any style.

The 12-bar blues

Most blues songs follow a 12-bar chord pattern using the I, IV and V chords of the key. In blues, all three are usually dominant 7th chords. In A: A7, D7 and E7.

That last E7 is called the turnaround: it pulls you back to the beginning.

The shuffle

Blues usually has a shuffle (or swing) feel: each beat is split "long–short", like a triplet with the middle note missing — daa-da daa-da.

The classic rock 'n' roll shuffle riff alternates between the power chord (1–5) and the 1–6, with a long–short rhythm:

e|-------------------------|
B|-------------------------|
G|-------------------------|
D|-2---2-4---4-2---2-4---4-|
A|-0---0-0---0-0---0-0---0-|
E|-------------------------|

Move the same shape one string higher for the IV chord (D) and one string lower for the V chord (E):

e|-------------------------------------------------|
B|-------------------------------------------------|
G|-2---2-4---4-2---2-4---4-------------------------|
D|-0---0-0---0-0---0-0---0-------------------------|
A|-------------------------2---2-4---4-2---2-4---4-|
E|-------------------------0---0-0---0-0---0-0---0-|

The blues scale

Add one note to the minor pentatonic — the ♭5 — and you get the blues scale: 1 – ♭3 – 4 – ♭5 – 5 – ♭7. That extra note is the famous blue note. Use it as a passing note between 4 and 5; don't stay on it too long.

e|---------------------------|
B|---------------------------|
G|-------------5-7-5---------|
D|---------7---------7-5-----|
A|-5-6-7-------------------7-|
E|---------------------------|

Major and minor together

Here's a secret of the blues: over dominant 7th chords, the minor pentatonic sounds great even though the chords are major. That clash between the major 3rd in the chord and the ♭3 in the melody is the blues sound. Bend the ♭3 slightly up toward the major 3rd for extra flavor.