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• Understand basic variations of both major and minor 12-bar blues forms.
• Learn how to emphasize the IV chord by using ii-V progressions.
• Create movement and interest with tritone substitutions.
To successfully participate in a jam session, whether it’s a formal session or just some friends getting together to pick in the living room, you’ve got to know tunes—or at least the chord progressions to those tunes. This is true of any style of music, including the blues. The focus of this lesson will be on the essential chord progressions you’re expected to know as a blues rhythm guitarist. We’ll survey chord patterns that every aspiring blues guitarist needs to know, so if you’re just getting started with the blues, this lesson should serve you well.
Let’s start off with the most common blues progression: the 12-bar form. Countless songs—in many styles—are based on this structure. Fig. 1 shows its basic form. Roman numerals indicate the quality of the chord (i.e., major or minor), as well as the position the chord occupies in the key. For example, if we’re in the key of A, the I chord is A, the IV chord is D, and the V chord is E. Uppercase Roman numerals indicate a major chord and lowercase Roman numerals indicate a minor chord. The benefit of learning a progression this way is it’s not locked to a specific key. This makes it easier to transpose the progression to a new key—you simply need to know the key you’ll be playing in and that becomes your I chord.
It’s common to move to the IV chord in the second measure and then back to the I chord in measure three. This is referred to as a “quick change.” If you’re jamming on a blues tune you’re unfamiliar with, keep your ears open because not all tunes employ the quick change.
A turnaround usually occurs in the 11th and 12th measures of the progression. These two measures set things up to bring you back to the top of the form. The turnaround ends with the V chord, and this creates tension. The ear wants to hear the resolution to the I chord, which it gets when the form starts over.
Now that we’ve laid the foundation for a basic 12-bar progression, let’s explore ways to embellish it. By the time we work through these variations, you’ll be able to negotiate everything from a simple blues to its jazzier adaptations. Fig. 2 shows a basic 12-bar blues with the quick change in the key of A. Both these examples serve as a starting point for the variations we’ll discuss from this point on.
For a moment, let’s focus on a few variations in the turnaround. The first one, shown in Fig. 3, is a I–IV–I–V turnaround in the key of A.
The next variation (Fig. 4) will prepare you for those situations when the bandleader calls for a 12-bar blues with a ii-V (pronounced “two-five”). The ii chord is a minor chord—indicated by the lowercase Roman numeral—built off the second note in the key. These last four measures of the form can be plugged into either of the first two examples we discussed. When this variation is used, the turnaround typically changes to include the ii-V as well. It has a strong pull to I, therefore it works well in a turnaround.
To vary the progression further, we’ll add the VI chord in the eighth measure (Fig. 5). This chord creates a pull to the ii chord we introduced in the previous example.
We can also incorporate the VI chord into the turnaround as shown in Fig. 6. This creates the common I–VI–ii–V progression.
In Fig. 4, we inserted the ii-V progression into measures nine and ten, as well as in the turnaround. Remember the ii-V has a strong pull toward the I chord. Because of this, we can place a ii-V in front of a particular chord we want to emphasize.
One of the characteristics that separates the 12-bar blues progression from others, and delivers what we’ve become accustom to hearing as “blues,” is the movement to the IV chord in the fifth measure. By viewing the IV chord as a temporary I chord and placing the corresponding ii-V before it, we harmonically emphasize the “new” I chord (which in the overall progression is really the IV chord). Play through Fig. 7 and listen to how the chord in the fifth measure (D7) is reinforced by the Em7–A7 that precedes it.