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Blues Theory

Basic Blues: 12-bar Blues theory 1995 by Olav Torvund

[Editor's note - Olav is sending us this lesson for Norway. Some of the musical terms he is using are spelled slightly differently from the way they are spelled in the U.S. (they are probably closer to the Latin than English allows) Wherever these spelling differences occur, I have added the U.S. English equivalent initially, but have left them in their original spelling throughout the lesson.]

I will start with a look at the basic 12-bar blues form, familiar to almost any guitarist. Every guitarist interested in blues, folk, country or rock should know the 12-bar blues by heart; Just switch on the "auto-pilot" and play.

In it's simplest form, it consist of three lines in AAB form. The first 4-measure line (motiv) [motif, motive - ed] is repeated with a slight variation, and then a new motiv is introduced in the third and concluding line. If we put chord numbers in the three lines, it will be:

1 2 3 4
| I / / / | I / / / | I / / / | I / / / |
5 6 7 8 | IV / / / | IV / / / | I / / / | I / / / |
9 10 11 12 | V7 / / / | V7 / / / | I / / / | / / / / |

I = tonika [tonic - ed], or the basic chord/note of the key you are playing.
IV = subdominant dominant 7th
If we apply the chord group to some key signatures, you will have the following chords:
E-major: I = E, IV = A, V7 = B7 (B7=H7 as the notation some European countries)
A-major: I = A, IV = D, V7 = E7
D-major: I = D, IV = G, V7 = A7
G-major: I = G, IV = C, V7 = D7
C-major: I = C, IV = F, V7 = G7.

Those of you who have a basic knowledge of music theory, will notice that I started in the key of E-major, and moved leftwards in the circle of fifths. All of you should notice that the subdominant (IV) chord in one key is the tonika in the key below, and that the dominant is the tonika in the key above.

Listen carefully to the dominant7 - tonika relationship. Listen how the dominant7 leads back to tonika. Those of you who are interested in music theory should notice that to some extent the dissonant minor fifth interval between the 7th note and the 4th note in a scale will be resolved by going to the tonika (1st note). (The 7th and 4th notes of the scale are the 5th and the 7th notes in the dominant 7th chord).

Let us again put it to the five keys (the dominant 7 in parenthesis):
Key 7th note 4th note Tonika E-major (B7): D# A E A-major (E7): G# D A D-major (A7): C# G D G-major (D7): F# C G C-major (G7): B F C.
Play the two related chords (V7 - I), and play the interval up (notes 7-4-1), down (notes 1-4-7) and as a block, each time resolving to the tonika.
Try also to substitute the IV of the scale with the II in the interval, and listen to the effect (E: A-> F#, A: D -> E, D: G -> E, G: C-> A, C: F->D). The II note is also part of the dominant7 chord, but you will then have a minor third interval instead of a minor fifth, and it does not call that much for an immediate resolution.

The dominant - tonika relationship is very important to any kind of western music, not only to blues. So listen carefully, and train your ear to identify it when you listen to music.

Now, let us go back to the 12-bar blues, and take a second look at the last line, bar 9 - 12. As it was written, the dominant7 is resolved to tonika from bar 10 to 11. If we substitute the tonika in the last bar with the dominant7, we will get a chord that leads back to the beginning. The dominant7 will be resolved when you start the next verse on the tonika chord. Then the last line will be like this:
9 10 11 12 | V7 / / / | V7 / / / | I / / / | V7 / / / |
The V7 chord functions as a TURNAROUND chord. It will sound even better if you hold the tonika chord for the first beat in bar 12, and change to V7 on the second beat.
You cannot end a song on that chord, so you have to play another verse. Be sure to end on the tonika when you do not want to play any more verses.

The last line is often played with a subdominant instead of a dominant7 in the 10th bar:
9 10 11 12 | V7 / / / | IV / / / | I / / / | I V7 / / |

In my ears the last line sounds better if you are using a turnaround V7 chord. There will be a bit too much of V7 if you play it both in the 10th and 12th bar, but that is a matter of taste. If you do not use a turnaround, both variations may sound well.

If we then go back to the first line, you can substitute the I chord on the last three beats in bar 4 with a I7 chord (i.e. from E to E7 in the key of E, etc). Then the line will be like this:

1 2 3 4
| I / / / | I / / / | I / / / | I I7 / / |
Listen to the effect: You put some tension to the last three beats of the line, and that tension is not resolved before you change to the IV chord in the second line. And if you go back an look at the relationship between the keys, you will realize that the 7-chord on the tonika is the dominant-7 to the IV chord. So what you do is to introduce some kind of a V7 - I relationship when you go to the second line. I do not know enough about music theory to decide if that is just a change of chords, or if you are actually changing key from I to IV, and then back to the I key (for instance from E-major to A-major, and then back to E-major in bar 7). But I do not think that it matters.
The IV chord in a blues is often substituted with the IV7 chord: In the key of E-major you will often play A7 instead of A. If you put all this in the 12-bar blues with a turnaround, it will be like this:
1 2 3 4
| I / / / | I / / / | I / / / | I I7 / / |
5 6 7 8
| IV7 / / / | IV7 / / / | I / / / | I / / / |
9 10 11 12
| V7 / / / | IV7 / / / | I / / / | / V7 / / |
In E-major, that will be:
1 2 3 4
| E / / / | E / / / | E / / / | E7 / / / | 5 6 7 8
| A7 / / / | A7 / / / | E / / / | E / / / | 9 10 11 12
| B7 / / / | A7 / / / | E / / / | / B7 / / |

Often you will hear a IV7 chord in the second bar instead of a I chord. The first line will then be like this:
1 2 3 4
| E / / / | A7 / / / | E / / / | E7 / / / |
Listen to the effect of the chords. Listen to other people playing, and try to identify if they are using I or IV7 chord in bar 2, if they go to the I7 or not in bar 4, if they play IV7 or V7 in bar 10 and if they use a turnaround chord.

You will soon realize that a lot of blues-like songs do not fit into a form like the one described. You should remember that the 12-bar blues form is not a rule for blues-players, it is just a label that has been attached to a common blues-form. But then you have a point of departure for ear-training: If you hear that the music played almost, but not exactly, fits into the form you know, then you know what to listen for and try out: What are the variations? What chord is being played? etc.

Remember that you should be a musician, not only a guitar player. You have to train your ears, not only your eyes and your fingers.
Olav Torvund 1995

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