The name 12 Bar Blues comes from the number of measures or bars in most blues songs – twelve. Here’s the basic 12 bar blues (Chicago blues) in the key of A.
Further On Up the Road – basic 12 bar blues
/ A7 /A7 /A7 /A7 / D7 / D7 /A7 / A7 / E7 / D7 / A7 / E7 /
A quick change is just that, changing chords in the 2nd measure and then back the the first chord.
/ A7 / D7 /A7 /A7 / D7 / D7 /A7 / A7 / E7 / D7 / A7 / E7 /
Blues musicians often refer to chord changes by Roman numerals after the steps of the scale. Below are the scale steps in the key of A and the chords associated with them.
I A (the key of the song)
II Bmi
III C#mi
IV D
V E
VI F#mi
VII G#dim
Many blues songs have just three chords, the I, IV and V chords. In the key of A, that’s A, D and E. Here’s Further On Up the Road by chord name and Roman numerals.
/ A7 / A7 /A7 /A7 / D7 / D7 /A7 / A7 / E7 / D7 / A7 / E7 /
/ I / I / I / I / IV / IV / I / I / V / IV / I / V /
And the quick change in Sweet Home Chicago? It’s to the …. IV chord …. Right!
/ A7 / D7 /A7 /A7 / D7 / D7 /A7 / A7 / E7 / D7 / A7 / E7 /
/ I / IV / I / I / IV / IV / I / I / V / IV / I / V /
1) The last 2 bars of the song are called the turnaround. The basic turnaround is
… / A7 / E7 /
2) There are many varations of the turn around. Here’s a common one
… / A7 D7 / A7 E7 /
Key to the Highway – uses the turnaround variation (#2 above)
/ A7 / E7 / D7 / D7 / A7 / E7 / A7 D7 / A7 E7 /
/ I / V / IV / IV / I / V / I IV / I V /
/ Am / Am / Am / Am / Dm / Dm / Am / Am / Em / Dm / Am / – /
/ I / I / I / I / IV / IV / I / I / V / IV / I / – /
A minor 12 bar blues usually has a repeated rhythm pattern and no chord in the 12 measure.
The chord number system comes in handy on a gig. If the band leader says “take it down from the fifth”, that means start the song from V chord in the 9th measure.
… / E7 / D7 / A7 / E7 /
… / V / IV / I / V /
And if someone points at you and holds up 4 fingers, it means play the IV chord now!
Bridge (B part of song)
Some blues songs have a “B” part or bridge. You’ll find this one in many songs.
/ D7 / A7 / D7 / A7 / D7 / A7 / B7 / E7 /
/ IV / I / IV / I / IV / I / II / V /
The ‘unexpected’ “IV” chord (instead of the I chord) creates tension and interest. Usual format – AABA.
Allman Bros. style layed back triplets
G9 / C9 / G9 G#9 / G9 /
C9 / C9 / G9 Ami7 / Bmi7 A#mi7 /
Ami7 / Cmi7 / G9 C9 / G9 D+ /
The Blues had a baby and they called it Rock N Roll. A comparison of the two styles that may open up your ears and improve your playing.
#1 Tempo / 8th Notes
Blues is usually slower – medium shuffle – played with dotted eight notes
Rock is usually uptempo – played with even eight notes.
#2 Changing Chords / Beat
Blues chords ususally change on the 1st beat of a measure
Rock chords change on the ‘&’ of the 4th beat in the previous measure – gives rock incredible drive.
#1 Rhythm Guitar / 1 Note or 2?
Blues- the rhythm guitar usually plays two notes together.
Rock- the rhythm guitar alternates between playing two notes together and a single ‘bass’ note