12 Bar Blues

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 🎼

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 · II · III · IV · V · VI · VII

In C major the note names are:

Rhythm: a quick primer 🥁

Rhythm time signatures consist of beats per bar.

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

The most popular time signature 4/4 is also called common time. Each bar consists of 4 beats of quarter notes (♩ = 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 (♪ = 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 · IV · 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: C · F · G.

The chord progression starts out simple and progressively adds more changes, ending with a final chord called the turnaround before repeating.

12 bar blues: Rhythm

As a intro, and in terms of the number of bars per chord the 12 bar blues rhythm formula looks like

4 · 2 · 2 · 1 · 1 · 1 · 1

So that is 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

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

12 bar blues: Changes

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

I · I · I · I · IV · IV · I · I · V · IV · I · V

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

Bringing it on home 🎸

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

C C C C · F F · C C · G · F · C · G

To break that down:

  1. four bars of I (C)
  2. two bars of IV (F)
  3. two bars of I (C)
  4. one bar of V (G)
  5. one bar of IV (F)
  6. one bar of I (C)
  7. one bar of V (G) - 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 pentatonic scale (I · flat III · IV · V · 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, mixylodian)