Blues scales are commonly used to solo over Major & minor blues, & over minor chords in general. Blues scales create a 'bluesy' feeling, or an 'earthy' quality. They are commonly used by Rock, Jazz, Blues, & R&B players. It can be viewed as a minor pentatonic scale with a flat 5. Its scale formula is R - b3 - 4 - b5 - 5 - b7 [R = Root, b = flat]. The b5 [like other scale components] can also be spelled [its letter name] as the #4 [sharp 4]. Related: Tone Naming & Derivative/Parallel.
We first look at a fretboard map of the blues scale for the entire board. This is shown without any particular fret as the root, as it is movable and maintains all of the relationships. We have left out tones outside of the octaves, just to keep it less cluttered. Use octave shapes to add in, if needed. Ultimately, our inner hearing guides our melodic playing, rather than maps or grids; yet they can help. We have numbered the octaves based on the strings. These names are under the map and are the framework for the Notation/Tab by Key.
For the Notation/Tab by key, we demonstrate all 7 of the octaves as closed systems for different roots [this way, when you figure them all out, you have the fingerings for all of the other keys]. And the ACGDE keys include open strings, but still conform to the octaves shapes [it is impossible not to]. There are other ways to finger [divide] some octaves; we are sharing some common fingerings [divisions]. Look at the map above for other pathways between the roots. The tones within the scales can also be named differently for some of the keys. I have used what makes most sense to me and not necessarily the exact alphabetical tone sequence [some enharmonic names are easier to remember than others]. I have chosen what it easiest to remember. It is good to remember.
And on the Talk in G tab, we explore how to apply these scales to basic blues in G. Basic meaning the I, IV, and V chord.
The tones in the C blues scale: C Eb F Gb G Bb. And, they are notated as these same tones. We have fretted this in octave 52 [the octave between the 5 & 2 strings], and have included an open string.
The tones in the Db blues scale: Db Fb Gb G Ab Cb. Yet, we have notated them as Db E Gb G Ab B. We are using octave 52 [octave between the 5 & 2 strings]. This scale could also be spelled C# E F# G G# B.
The tones in the D blues scale: D F G Ab A C. They are notated as these tone names. We are using octave 42 [octave between the 4 & 2 strings], and including a couple of open strings.
The tones in the Eb blues scale: Eb Gb Ab Bbb Bb Db. Yet, we will name the b5 as an A for simplification. Since Bb is the 5, Bbb [B double flat] will be the flat 5. That's no fun. Let's call it A. We are using octave 42 [the octave between the 4 & 2 strings].
The tones in the E blues scale: E G A Bb B D. And, we are notating them as these tones. We are using octave 64 [the octave between the 6 & 4 strings]. This scale is also covered in E minor Type Things.
The tones in the F blues scale: F Ab Bb Cb C Eb. We will call the flat 5 B, rather than Cb. We are using octave 41 [the octave between the 4 & 1 strings].
The tones in the F# blues scale: F# A B C C# E. And, we are using the same names. Since the 5 is C#, flatting it gets us a C natural. We are using octave 64 [the octave between the 6 & 4 strings]. This scale could be spelled in Gb, but it gets a little wild. It would be Gb Bbb Cb Dbb Db Fb, which could be simplified to Gb A B C Db E [which is just renaming the F# & C# as Gb & Db].
The tones in the G blues scale: G Bb C Db D F. And, we are using the same names. We are using octave 31 [the octave between the 3 & 1 strings], starting on an open string.
The tones in the Ab blues scale: Ab Cb Db Ebb Eb Gb. Yet, we will name the tones this way: Ab B Db D Eb Gb. We are using octave 63 [the octave between the 6 & 3 strings]. This scale could be named G# Blues [G# B C# D D# F#].
The tones in the A blues scale: A C D Eb E G. And, we are using the same names. We are using octave 53 [the octave between the 5 & 3 strings], using open strings.
The tones in the Bb blues scale: Bb Db Eb Fb F Ab. We will rename the Fb, just E. We are using octave 31 [the octave between the 3 & 1 strings].
The tones in the B blues scale: B D E F F# A. And, we are using these names. Since the 5 is F#, flatting it gets us a F natural. We are using octave 53 [the octave between the 5 & 3 strings].
We can use the G blues scale [G Bb C Db D F] to solo over 12 bar blues in G [G7 = I7, C7 = IV7, D7 = V7]. In this instance, we are making a single scale choice for an entire harmonic progression.
When playing a blues scale (the minor pentatonic with the b5) over G Major blues, we may hear some 'clashing'. It is common to make modifications [mods] to the scale to match up the sounds.
The tones in G7 are G, B, D, & F. Our first modification is adding the Major 3rd to the scale while the G (or G7) is sounding. We can keep the b3, as this gives us the blues sound [we typically slide it into the Major 3rd - the B].
The tones in C7 are C, E, G, & Bb. We can just play G minor pentatonic over the C chord. The G blues scale matches the C chord in a good way.
The tones in D7 are D, F#, A, & C. While adding the D7 is sounding, we add a F# to the scale. We can keep the F, using it as a passing tone [move through it]. And, the Db that is in the G Blues would definitely need to act as a passing tone. At some point with the V7 chord, we have to make so many mods, it might just be better to use a different scale. We have choices (even in how we think about all of this).
Another option is to switch to each of the corresponding blues scales for the given chord root. When playing blues in G Major, play G blues scale with the G7 chord, C blues scale for the C7 chord, & D blues scale over the D7 chord.
Keep in mind that the 'blues' scale is a minor type scale, so it can be called the minor blues scale. When we add the Major 3rd to the blues scale, we can call it the Major b3 Blues scale.
And, another option for Dominant type chords [G7, C7, D7], it to use the corresponding Mixolydian [Major scale with a b7].
The flat 5 is also the sharp 4 (the tritone - 3 whole steps - 6 half steps) & can be named the # name as in some of our notated examples. This tone acts as a passing tone, not a strong beat tone. It can occur as a connection tone between the 4 & 5 within the melodic motion.
For minor type chords [such as G minor blues], the blues scale is a good fit. It is also common to alternate between the Dorian mode (R-2-b3-4-5-6-b7) & the blues scale for the minor, depending on the type of sound you are wanting.