Those who want to play blues, should know the blues scale. Guitar players should know how to finger blues scales all the way up the neck in the so called "box position". But let us start with some peculiarities of blues tonality. If you start from the root note and play a scale, a major scale is like this: (A major scale is often called a diatonic scale):
I + II + III - IV + V + VI + VII - I.
In the most favored blues-guitar keys, it will be (starting in C-this time):
C: C + D + E - F + G + A + B - C
G: G + A + B - C + D + E + F# - G
D: D + E + F# - G + A + B + C# - D
A: A + B + C# - D + E + F# + G# - A
E: E + F# + G# - A + B + C# + D# - E
If there is a + between two notes, it indicates a whole step (two frets), and - means a half step (one fret). The interval between notes I and III determines if it is major or minor scale: A major third, consisting of two whole steps (four frets) between the I and III notes gives major, and a minor third with one whole and one half step (three frets) between notes I and III gives minor. The blues scale is like this:
I + - IIIb + IV + V + - VIIb + I.
In the five keys, it will be:
C: C + - Eb + F + G + - Bb + C
G: G + - Bb + C + D + - F + G
D: D + - F + G + A + - C + D
A: A + - C + D + E + - G + A
E: E + - G + A + B + - D + E
It consists of 5 notes, compared to the 7 notes in the major scale. Notice that there is no II or VI notes, and the III and VII notes are lowered one half step. If we write a major and a blues scale in parallel, they look like this:
Major: I + II + III - IV + V + VI + VII - I
Blues: I + - IIIb + IV + V + - VIIb + I
The interval I + - IIIb is a minor third, that should indicate a minor scale. But a blues melody is usually played over major chords. And a major chord consists of the notes I + III + V. So we will often play a melody based on a scale with a minor third over chords with a major third. For that reason, blues does not have a very well established tonality, and that is part of the blues-sound.
You should also note the VIIb in the blues scale, compared to the VII in the major scale. If you read my lesson about the 12-bar blues form, you will remember that I stressed the dominant-7 to tonika [tonic - ed] relationship, and I stressed the effect of the intervals built on the VII note: First of all the minor fifth interval from the VII note to the IV note, but also the minor third interval from the VII note to the II note. Now you can notice that both the VII note and the II note are omitted from the blues scale, but are still part of the blues-harmony. Let us then introduce the "box positions":
| | | | | |
+---+---+---+---+---+
| | | | | |
1 4 7b 3b 5 1
| | | | | |
+===+===+===+===+===+
| | | | | |
| | | | | |
| | | | | |
+---+---+---+---+---+
| | | | | |
| 5 1 4 | |
| | | | | |
+---+---+---+---+---+
| | | | | |
3b | | | 7b 3b
| | | | | |
+---+---+---+---+---+
| | | | | |
Box 1. The numbers refer to the numbers in the scale. I will refer to the fret marked with a double line as the position. If you play it in 5th position, you will be in the key of A, 8th position will give you C, and note that both the 12th and the 0th (open) positions give you the key of E.
| | | | | |
+---+---+---+---+---+
| | | | | |
| 5 1 4 | |
| | | | | |
+===+===+===+===+===+
| | | | | |
3b | | | 7b 3b
| | | | | |
+---+---+---+---+---+
| | | | | |
| | | 5 | |
| | | | | |
+---+---+---+---+---+
| | | | | |
4 7b 3b | 1 4
| | | | | |
+---+---+---+---+---+
| | | | | |
Box 2: 7th pos -> A, 10th pos -> C, 12th pos and open -> D, 2nd (and 14th) -> E.
| | | | | |
+---+---+---+---+---+
| | | | | |
| | | 5 | |
| | | | | |
+===+===+===+===+===+
| | | | | |
4 7b 3b | 1 4
| | | | | |
+---+---+---+---+---+
| | | | | |
| | | | | |
| | | | | |
+---+---+---+---+---+
| | | | | |
5 1 4 7b | 5
| | | | | |
+---+---+---+---+---+
| | | | | |
| | | | 3b |
| | | | | |
Box 3: 9th pos -> A, 12th pos and open -> C, 2nd ps - > D, 4th pos - > E.
| | | | | |
+---+---+---+---+---+
| | | | | |
5 1 4 7b | 5
| | | | | |
+===+===+===+===+===+
| | | | | |
| | | | 3b |
| | | | | |
+---+---+---+---+---+
| | | | | |
| | 5 1 | |
| | | | | |
+---+---+---+---+---+
| | | | | |
7b 3b | | 4 7b
| | | | | |
+---+---+---+---+---+
| | | | | |
Box 4: 12th pos and open - > A, 3rd (and 15th) pos -> C, 5th pos -> D and 7th pos -> E.
| | | | | |
+---+---+---+---+---+
| | | | | |
| | 5 1 | |
| | | | | |
+===+===+===+===+===+
| | | | | |
7b 3b | | 4 7b
| | | | | |
+---+---+---+---+---+
| | | | | |
| | | | | |
| | | | | |
+---+---+---+---+---+
| | | | | |
1 4 7b 3b 5 1
| | | | | |
+---+---+---+---+---+
| | | | | |
Box 5: 2nd pos - > A, 5th pos -> C, 9th pos -> E, 12th pos and open -> G.
Class Assignment:
Have someone play a 12-bar blues accompaniment or play along with a tape. Practice those 5 boxes in the 5 keys mentioned. Listen carefully how the scale works over different chords. After a while you will realize that it is boring to play the scale up and down. You must play melodies, and you have to utilize notes outside the blues-scale as "spices" in your playing. But we will cover that in a later lesson, where we will look at some blues-licks.
- Olav Torvund.
/ my profile 
