Twelve Bar Blues

8 minute read

As I mentioned before, scales and chords can be regarded as the ribs and spine of harmonica playing, or any form of music for that matter. However, like any skeleton, the individual bones are not much use unless their put together in the right order and in the right place. The same is true for the musical skeleton.

Chord Structures

Just as certain notes sound good together when they are played as chords, certain chords can be combined to form a chord structure. A chord structure is basically a series of chords played in a certain order, with each chord played for a certain period of time; and that is basically it. Just as scales can be considered the musical alphabet, so to can chords be considered the words and chord structure the phases or sentences. Putting this all together we can see how different words can convey different meanings, just like major or minor chords create different sounds. When put together into sentences these can deliver complete messages designed to provoke thoughts or feelings.

For example, consider the phrase:

Fair is foul, and foul is fair. Hover through the fog and filthy air.

Now, you may not know where that phrase came from, who said it, and to whom, but you can hazard a guess that it is not particularly pleasant. The words “foul” “fog” and “filthy” are not exactly going to inspire you to wrap Christmas presents. Even the word “fair” slotted in occasionally does not seem to improve the idea behind it. Now, if the same words were thrown together in a totally random order (for example, “Hover foul, and the foul air fog is and filthy fair through is fair.”) the effect would not be nearly as powerful. You might get a rough idea of what was going on in the background, but you it would hardly sound as scary. The same is true for music: by combining all the elements together in a way that is understandable and makes sense you can tell stories, throw tantrums, or confess love by making noises on a small, tinny instrument. Incidentally, it was the witches in Shakespeare’s Macbeth casting a curse at the beginning of the play. Charming.

There are many different types of chord structure. Some styles of music, such as Blues, have just a single, main chord structure, whereas others like Rock, Pop, and Jazz can have any number of different chord structures ranging from several to several hundred.

Twelve-Bar Blues Chord Structure

The Twelve-bar Blues is the bedrock of Blues music. It is the foundation that one builds on, the basic script that begins “Once upon a time…” and finishes with “… happily ever after.” From the chord structure you can work out how it starts and ends, and all you need to do is jazz up the story-line with a few interesting notes and chords. Just like several hundred swear words, a couple of car chases, and the odd debate about birth control can turn an otherwise boring Tarantino script into something just about bearable.

Now, the twelve-bar Blues is by no means the only chord structure used in Blues, but it is the most popular and (thankfully) probably the easiest to learn. It also appears frequently in a lot of Rock, Jazz and Country music. If you want to learn how to play the Blues anywhere with anyone, then you will need to learn the twelve-bar Blues. No question.

Before we continue, I should clear up one or two things you may not be so familiar with: The word bar refers to a set number of beats within a piece of music; usually three or four beats of time. If you have ever seen a piece of written music, you will have noticed the vertical lines dividing the horizontal strips where the musical notes are written. These lines represent the end of a previous bar and the beginning of the next. They are often used as guides to split music up into smaller pieces; much in the same way that a written paragraph is divided into sentences and phrases. They help musicians keep their rhythm (the regular pacing beat to which music is played), which makes music easier and more pleasurable to hear. This is important because (going back to the analogy with written language) if you can imagine how an orator, actor or politician sounds when they give a stirring monologue (the good ones at least), they often try to keep their speach patterns fluid and regular; this makes their words easier to follow and understand. Try imagining how effective such speeches would be if the speaker decided to speed up and slow down at random; not only would they be less effective, they would sound completely ridiculous.

Usually, a single bar is divided into four beats; so a twelve-bar Blues would be 12 x 4 = 48 beats. This twelve-bar structure is usually repeated three or four times, and each repeat is called a verse. You can think of verses as being like chapters in a book: each part of the same story, but different plots, characters and situations. The twelve-bar Blues usually has just three chords, and these chords always have the same relationship to each other: they are chords formed on degrees I, IV, and V of a major scale. They are also refered to as the tonic chord, subdominant chord and dominant chord. These three chords can be either major, minor or 7th chords, depending on the type of character you want your music to have.

Twelve-Bar Blues in G

It may seem surprising when I tell you that, when using a C harmonica, the easiest twelve-bar Blues to play is in the key of G. I will explain why this is later on when we discuss harmonica positions, but for the moment suffice it to say that the reason is because the three chords needed for a twelve-bar Blues in G (namely G, C and D) are all conveniently located on the C harmonica.

C Harmonica

Looking at the layout of the C harmonica once again, you may recall from the section on harmonica history that blowing into any three holes in a row will produce the C major chord (C-E-G); drawing on holes 1, 2 and 3 will produce the G major chord second inversion (D-G-B); drawing on holes 2, 3 and 4 will produce the G major chord root position (G-B-D); and drawing on holes 4, 5 and 6 will produce the D minor chord (D-F-A). If you delve a little deeper you will notice that drawing on holes 2, 3, 4 and 5 will produce a dominant 7th chord in G (G-B-D-F). This is really good news because pretty much any 7th chord is guaranteed to sound Bluesy. Remember that the dominant 7th chord is formed on the dominant degree (V) of a major, harmonic or melodic minor scale. In the case of C major/minor, the dominant note is G. If we look at the notes within each major and minor scale in C, we can see how the dominant 7th chord in G is formed by notes G, B, D and F.

Notes of the Major and Minor C Scales

Degree I II III IV V VI VII I
Major C D E F G A B C
Natural Minor C D Eb F G Ab Bb C
Harmonic Minor C D Eb F G Ab B C
Melodic Minor C D Eb F G A B C

It becomes clear that all the scales contain the notes G, B, D and F, except the natural minor in C which has a flattened B (and so can form a dominant 7th chord). Incidently, drawing on hole 2, 3, 4, 5 and 6 together produces a major dominant 9th chord, but that is beyond the scope of this tutorial.

It seems amazing that so much versatility is contained within one small, tinny sounding instrument. But there you have it: a multitude of chords available for adding colour, style and character to music, all perfectly located for playing the Blues.

Chord Structure

So finally we are going to get down to the actual chord structure. Sorry it took so long, but hopefully you will be wiser for the longer route.

Twelve Bar Blues in G

Chord Total Beats Number of Bars Degree Names
G 16 4 I (Tonic)
C 8 2 IV (Subdominant)
G 8 2 I (Tonic)
D 4 1 V (Dominant)
C 4 1 IV (Subdominant)
G 8 (inc. Turnaround) 2 (inc. Turnaround) I (Tonic) (inc. Turnaround)

If you practise with passion then very soon you will find yourself following this structure without even thinking about it. Listen to a few well-played Blues tunes and see if you can follow the beat and spot the places where the chords changes occur. After a while it will seem like second nature.

Turnaround and Introduction

Many twelve-bar Blues tunes end each verse with a turnaround: this is basically a few beats worth (usually two to four) of the dominant chord (V) at the very end of a verse intended to build tension and give a clear warning that the next twelve-bar is about to start. Have a listen to some classic tunes and you will likely hear turnarounds in each of them.

Less common (but still reasonably popular) is the introduction: this is usually a short chord structure (usually two or four bars long) designed to launch the musicians into the main twelve-bar Blues part of the tune. There are two main types of Introduction: the first is two bars long and is identical to the last two bars of the twelve-bar Blues (i.e. two bars of the tonic chord including a turnaround); the second is four bars long and is identical to the last four bars of the twelve-bar Blues (i.e. one bar of the dominant chord, one bar of the subdominant chord, and two bars of the tonic chord including a turnaround). Introductions are usually less of a worry to a harmonica player, because they are generally not expected to provide the lead-in to a tune. Plus, it is much easier to join in a tune once you have the rhythm in your head.