The most common blues chord progression is the 12-bar blues.
This fundamental chord progression is featured prominently in blues music and forms the basis for many rock, jazz, country and R&B songs.
This post will cover the basic elements of a 12-bar blues chord progression and provide instruction on how to play the progression on a guitar in any key.
Chords
The 12-bar blues chord progression is based on the I, IV and V chords in any given key and all three chords are usually dominant seventh in quality.
For example, a basic 12-bar blues in the key of E would typically include the chords E7, A7 and B7.
The Roman numerals representing the dominant seventh chords would be I7, IV7 and V7.
Format
Slow Change Blues
The 12-bar blues progression’s most common format is often called a slow change blues and is shown in fig.1 (in the key of E).
Fig.1
Quick Change Blues
A quick change blues incorporates a minor variation into the standard blues format shown above.
In a quick change blues progression, the IV7 chord is played in the second measure before returning to the I7 in the third measure.
The rest of the progression follows the same format as a standard, slow change blues.
A basic 12-bar blues in the quick change format is shown in fig.2.
Fig.2
Rock Blues
While a 12-bar blues chord progression is typically played with dominant seventh chords, it is common for a rock version of the progression to be played with power chords, alternating in patterns with other diads (two notes played together).
For example, a basic rock blues in the key of E would typically include the chords E5, A5 and B5.
The Roman numerals representing the power chords would be I5, IV5 and V5.
A basic rock blues in the key of E is shown in fig.3.
Fig.3
Transposition
To transpose a song, chord progression or melody means to play it in a different key.
To play a 12-bar blues in any given key, first we need to identify the I7, IV7 and V7 chords in that key.
Identifying the Chords
Write Out the Scale
One way to identify the I7, IV7 and V7 chords in any given key is to write out the major scale that corresponds to the key we want to play in and then play the dominant seventh chords (or power chords) built on the first, fourth and fifth degrees of the scale.
For example, if we wanted to play a 12-bar blues progression in the key of A, we would write out an A major scale and play the dominant seventh chords built on the first, fourth and fifth notes in the scale (fig.5).
Fig.5
The first, fourth and fifth notes in an A major scale are A, D and E. So the chords to play are A7, D7 and E7.
A basic 12-bar blues in the key of A is shown in fig.6.
Fig.6
Look at a Guitar
A faster and easier way to identify the I7, IV7 and V7 chords in any given key is to look at a guitar.
The root notes of the chords are always on the same frets in relation to one another.
If we use a note on the sixth string to represent the I chord:
- The root note of the IV chord is located on the fifth string, on the same fret.
- The root note of the V chord is located on the fifth string, two frets higher than the root note of the IV chord.
Example #1
If we wanted to play a 12-bar blues in the key of A, the A on the sixth string, fifth fret would represent the I7 chord (fig.7, highlighted in red).
- The root note of the IV7 chord is located on the fifth string, fifth fret — D (highlighted in blue).
- The root note of the V7 chord is located on the fifth string, seventh fret — E (highlighted in green).
So the I7, IV7 and V7 chords in the key of A are A7, D7 and E7.
Fig.7
Example #2
If we wanted to play a 12-bar blues in the key of G, the G on the sixth string, third fret would represent the I7 chord (fig.8, highlighted in red).
- The root note of the IV7 chord is located on the fifth string, third fret — C (highlighted in blue).
- The root note of the V7 chord is located on the fifth string, fifth fret — D (highlighted in green).
So the I7, IV7 and V7 chords in the key of G are G7, C7 and D7.
Fig.8
A basic 12-bar blues in the key of G is shown in fig.9.
Fig.9
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