The 12-bar blues is by far the most popular form for the blues. Once you learn to play the 12-bar blues on the guitar, you can play such classic blues pieces as "Hound Dog," “Stormy Monday,” “Kansas City,” “St. Louis Blues,” “Easy Rider,” and “Corrina, Corrina.” Each of these songs follows the 12-bar blues pattern of three lines per verse, with the first line repeated.
Take a look at the figure. It consists of 12 measures and observes a particular scheme. Notice the use of Roman numerals instead of letter names, indicating that the progression is the same in every key.
For example, if you play blues in E, then E is the I chord, A is the IV chord, and B or B7 is the V chord. So with the corresponding letters substituted for the Roman numerals, the progression looks like the following figure. B7 replaces B because B7 is the easier of the two chords to play. Technically, you could play B as a barre chord on the second fret.
Because the slashes (/) leave some interpretation in what you’re playing, try this exercise with shuffle eighth notes (eighth notes that have a long-short rhythm scheme) in alternating downstrokes and upstrokes.
The quick four
The quick four is a variation on the 12-bar blues with a different second bar. Instead of staying on the I chord for four measures, you play a IV chord — for example, A in the key of E — in the second measure for one bar, and go back to the I chord for two bars. The quick four provides an opportunity for variation and interest in an otherwise unbroken stretch of four bars of the same chord.
The quick four happens just about as often as not in blues songs. Some songs that use the quick-four method include “Sweet Home Chicago” and “Hide Away.”
The quick four happens very soon after you start the song, so if you’re at a jam session, or are playing along with a song for the first time, you must be on your toes to anticipate its use.
The turnaround
The turnaround is the last two bars of the progression that point the music back to the beginning. At the end of the 12-bar blues, you can repeat the progression or end it. Most of the time you repeat the progression to play additional verses and solos. To help get the progression ready for a repeat, employ a turnaround that sets up the repeat. At the most basic level, you can create a turnaround by just substituting a V chord for the I chord in the last measure.
While the most basic application of a turnaround is just playing a V chord in the last bar, to most guitarists, a turnaround presents an opportunity to play a riff or lick. The following figure shows the last four bars of a 12-bar blues with a turnaround bar added.
You may see the V chord in the turnaround bar with parentheses around it. This method is shorthand for saying that you use the turnaround whenever you decide to repeat the progression. When you want the progression to end, ignore the parentheses and continue playing the I chord from the previous measure.
