12 Bar Blues

Created: October 2, 2019

You might have heard of the blues, made famous as a way to make a living in the US for marginalized citizens.

The story goes that the French taught the Black community music theory and unlocked a creative juice thirsting for expression.

12 bar blues is very basic music lesson and is known universally by musicians as a way to quickly join other musicians musically.

Scales: a quick primer 馃幖

The most common western scale - the major scale - has 7 notes representing pitch.

In any key or scale, they can be referred to by roman numerals: I 路 II 路 III 路 IV 路 V 路 VI 路 VII

In C major the note names are:

Rhythm: a quick primer 馃

Rhythm time signatures consist of beats per bar.

A bar is a measure of time for beat duration’s (quarter note 鈾, eighth note 鈾, etc).

The most popular time signature 4/4 is also called common time. Each bar consists of 4 beats of quarter notes (鈾 = 1/4). It can be vocalized simply as one, two, three, four.

A time signature of 5/8 would mean 5 beats of eighth notes (鈾 = 1/8). It can be vocalized as one and two and three and four and five.

12 bar blues: Chords

The chords used in the 12 bar blues are the root, fourth and fifth (I 路 IV 路 V).

Using these basic melodic notes we can create a rhythm pattern for any key.

In key of C from the example on scales, the notes used would be: CFG.

The chord progression starts out simple and progressively gets more complicated before repeating.

12 bar blues: Rhythm and Changes

As a intro, the 12 bar blues rhythm formula looks like

4 路 2 路 2 路 1 路 1 路 1 路 1

It is in terms of bars per chord progression (4 bars of a chord followed by two bars of another and so on). The total of these values is 12 hence the title 12 bar blues

If we apply the roman numerals I 路 IV 路 V from the 12 bar chords to this pattern it looks more like:

I I I I 路 IV IV 路 I I 路 V 路 IV 路 I 路 V

Which is four bars of the first, two bars of the fourth, and so on.

You might also find it interesting to see a pattern with 4 and its sums: 4 = 2 + 2 = 1 + 1 + 1 + 1

Bringing it on home 馃幐

Applying note values to the previous pattern in the key of C, the 12 bar blues now looks like:

C C C C 路 F F 路 C C 路 G 路 F 路 C 路 G

To break that down:

  1. four bars of C (I)
  2. two bars of F (IV)
  3. two bars of C (I)
  4. one bar of G (V)
  5. one bar of F (IV)
  6. one bar of C (I)
  7. one bar of G (V) - also called the ‘turnaround’ back to the beginning.

Oh, how convenient, that is also 7 key changes, just like the number of notes in a scale. Lucky 7 I guess.

Practising and Next

Get a feel for the notes, and use a metronome to count the rhythm per bar as you play them. Most people will play using the minor pentonic scale (I 路 flat III 路 IV 路 V 路 flat VII).

Jazz Blues is a variation that I will leave to another post. Not quite sure which came first, but I would wager it would be a predecessor to the 12 bar blues.

There is also a lot of other things you can do to add flavor to the blues.

  • ‘Walking’ the notes in the scale
  • lead in/lead out notes
  • ‘turnaround’ riffs
  • rhythm changes
  • pattern variations
  • solo in different modes (dorian is nice)

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