Contrary to what I thought when I first started, the blues are far from simple! Even though the blues uses just three chords, the reasons behind them all being dom7 chords, for example are pretty complex. Things really get interesting when people like Brian Wilson or Ornette Coleman get involved.
Still, a 12-bar blues almost always follows roughly the same chord changes. It usually moves to the IV chord in bar 4, for example, then back to the I in bar 6, and has some sort of turnaround in the last four bars.
If, like me, you want to solo and vamp freely over what other musicians are playing, you’ve got to know what chord is playing right now. You also need to anticipate what’s coming up next (and precisely when). Solos sound best when you “play the changes” and hit chord tones precisely as the chord changes. Having a fairly static, consistent progression like the 12-bar form makes this process at least a little easier.
Before you can start playing the changes, however, it’s critically important to absolutely nail the fundamental rhythm of the blues. It’s also necessary to internalize the changes, playing them over, and over, and over, and over again until you can anticipate the changes without any conscious thought.
In other words, you must nail the fundamentals before moving onto more complex things like playing the changes.
Rhythm: Swung Eighths
The first and most important fundamental for any music (not just the blues) is rhythm.
You can get away with murder (completely muffing notes and chords) as long as your rhythm is tight. The opposite is definitely not true, however. Even perfect melody/harmony/articulation sounds awful if the rhythm is off.
The fundamental rhythmic groove of the blues is based on triplets and swung eighths.
Straight eighths are more common in rock and other music. Straight eighths sound like:
One-and two-and three-and four-and
with equal spacing between each pulse (downbeat or “and”). A blues progression with a fast straight eighths groove immediately sounds rock-and-roll (tap along to Johnny B. Goode by Chuck Berry, for example).
Triplets have three pulses per beat:
One-and-a two-and-a three-and-a four-and-a
Again, equal spacing between each of the pulses, but triplets come in groups of three rather than two. The gap between each beat of three pulses is the same as the gap between each pulse within a beat (but usually the first pulse in each group of three is emphasized a bit more by strumming a little harder). An example of the triplet feel is Blueberry Hill by Fats Domino (listen to the drummer playing the hi-hat — those are triplets).
Swung eighths are kind of like triplets, but without the middle pulse:
one-…-a two-…-a three-…-a four-…-a
The spacing is unequal with swung eighths. There is a longer pause between the downbeat and the upbeat. Matt Smith describes the sound as the “clip-clop” of horses in old western movies. Some people also call it the “flat tire” rhythm because of the uneven sound of a punctured tire rolling around the rim. A classic example of the swung eighth groove is Jimi Hendrix playing Red House (again, pay particular attention to the drums to hear the rhythm — a mix of triplets and swung eighths).
Before studying anything else with the blues, it’s important to practice actually playing swung eighths with a metronome. I’d recommend spending at least a few hours if not days just practicing this rhythm until it is completely ingrained and automatic.
Modern blues tends to emphasize the backbeats. In slower tempos, the backbeats are the “ands” (or a’s) rather than the downbeats. At faster tempos, it’s beats two and four. Simply emphasizing the backbeat can dramatically improve the overall groove of the progression.
Not losing your place within 12 bars
Even though the basic 12-bar blues has a simple structure, and the chords almost always come in the same place, that doesn’t mean it isn’t easy to get lost.
Personally, I found it incredibly easy to get lost while I was playing. I was using so much mental capacity performing whatever I was doing (remembering chords, licks, tricky rhythms, whatever) that I lost place within the progression. Wait, is this bar 4 or bar 8?
When you lose your place in a band situation, it’s almost always best to just take your hands off the guitar and wait a few measures until you are certain where you are before picking up again. Silence will invariably sound better than something flat wrong.
The only way to avoid getting lost at all is to practice the progression so many times that it becomes subconscious. It’s also important to eliminate any unnecessary complexity and just focus on the progression until you hear it in your sleep.
Before studying anything else with the blues, I strongly recommend putting in some serious practice on just these two elements: the swung eighth rhythm, and starting to hear and anticipate the changes in the chord progression.