Blues scale

From the pentatonic pattern to the blues scale

The article The pentatonic as a first improvisation explains the route: if you begin the major pentatonic C – D – E – G – A at A, the minor pentatonic arises with the same five notes. It is the basis of almost all rock and blues solos. Add a single further note, the diminished fifth, in A minor the E♭, and you have the blues scale.

Between D, E♭ and E there are two semitone steps in a row. The article describes why this works: the pentatonic has no semitone and so no friction; the blue note is the one deliberately placed. It is therefore usually not held but passed through.

A second blue note

The page Intervals describes the minor seventh in the blues as a typical “blue note”. The seventh that is often sung or played in the blues corresponds more to the natural seventh harmonic in the ratio 7:4, which lies somewhat lower than the equal-tempered minor seventh, by about 31 cents. The blues sound therefore comes not only from the added note of the scale but also from the way notes are played.

Practising without an endless loop

On the guitar the pentatonic pattern can be played up and down for as long as you like without anything going wrong, and that is exactly what becomes the trap: movement without a statement. The remedy according to the article: self-restriction, such as three notes for a whole solo, or phrases that begin the same way twice and end differently the third time. Phrases need endings: after every two bars a rest of half a bar.