When soloing over a blues progression it is important to know which blues guitar scales will work and sound good. Essentially a blues progression is based on a I, IV, V chord progression and the most common is the 12 bar blues. In blues,these chords tend to be the same type of chords, ie ; major, minor or seventh chords. For example the most common 12 bar blues will be entirely seventh chords, a minor blues may contain only minor chords, and a major blues only major chords.
If we take the blues progression containing only seventh chords, we will find that one scale will not fit these chords perfectly, in a musical sense. If we try to match a scale with the chords, we could play the mixolydian mode over the I chord, in the same key of the I chord. We could take this approach to the other chords and play the mixolydian mode in the same key over the IV chord and V chord. This is one approach to solo over this type of progression.
A blues progression can also be constructed around entirely major chords in the I, IV, V pattern. In this instance, use the I major scale to solo with. It will fit perfectly with the chords, and it will difficult to hit a wrong sounding note.
A blues progression can be constructed with entirely minor chords. In this case use the natural minor scale to solo with. This scale will fit perfectly over this progression, because the chords contain the exact same notes as the corresponding scale.
What I would like to do now is explain the most common blues guitar scale and when it is best suited. This scale is simply called the blues scale and it is the minor pentatonic scale with a flat 5 added to it – R, flat 3, 4, flat 5, 5 and flat 7. Now remember I mentioned that the most common blues progression is constructed entirely with seventh chords(R,3, 5,flat7). This is the scale of choice to play over this type of progression. So you might be wondering why this scale has a flat 3 or minor 3rd in it – it doesn’t make musical sense using a minor 3rd over a major 3rd! Well, put simply this is what gives the blues such a distinctive sound – the flat 5 also gives this “bluesy” sound.
I hope you’re not too confused by now! So, to find a scale to solo over a typical blues progression, typically a I, IV, V chord progression, firstly look at the I chord. If it is a seventh chord, you could match each chord with the mixolydian mode in three different keys. You could also just use the minor pentatonic scale or the blues scale in the key of the I chord. For example if the I chord is a B seventh, you would use the B blues or minor pentatonic scale. If it is a B major or B minor as the I chord you would use the B major and the B minor scales respectively. You could also just use the B blues scale over these two progressions as well, or a combination. When playing the blues you have many options available to you, so have some fun and experiment with these various blues guitar scales.
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