12 Bar Blues is a pattern of chords which repeats every 12 bars. This progression is invaluable to the bass guitarist because of its use in many songs. For example, songs performed by Elvis Presley, Chuck Berry and the Beatles, such as "Hound Dog", "Johnny B. Goode" and "Roll Over Beethoven" are all based upon a 12 bar progression (see Appendix Three .)
Music Repeat Sign: This indicates that the progression is repeated from the beginning. After the repeat, the progression finishes on the opening chord (in this case, an A chord). This practice will apply throughout the book.
The following example (and Example 1) uses a root note bass for each chord. A root note is the note with the same name as the chord and will always blend well with that chord.
Finish the progression with an A note held for four counts