So, why does a minor pentatonic work over a major blues?

Yorkie

Major and minor. Up and down the rollercoaster. I gave you seven children. And now you wanna give 'em back!

Stuckfast

How often do blues musicians fully state the chords? It might be convenient to notate a typical 12-bar as containing A, D and E for example, but it seems to me that in a lot of cases it's only the root and fifth that are actually played, with the major third perhaps used as an occasional passing note in the bass.

Tannin

Let's look at this from a different direction (these thoughts prompted by @Stuckfast's post above). What are the notes that you most likely want to play  in a blues or blues-like context? Let's list them from first-choice down to last choice (i.e., the note you are least likely to want to play over (say) a 1 chord or a 5 chord. (The first few are pretty much equal priority, it drops away from there.)

1: tonic
2: b7
3: 5th

After that, the thirds, but you are almost as likely to play a minor as a major 3rd, so:

4: 3rd
5: minor 3rd

Then the non-chord tones which are nevertheless part of the key (insofar as blues has a key

6: 2nd (9th)
7: 6th

Now we get to the fun bits:

8: flat 5
9: b6 (aka b13, aka minor 6th, aka #5)
10 b2 (b9)

And the leftovers -

11: 4th - probably the least "bluesy" note, other than -
12: maj7 - almost never used

You almost certainly won't want to use all of them in a single passage or even in a single song, and I find it's usually best to make a selection - for example, one or other of the two 3rds, with the other no more than a passing note. (Lots and lots of blues/blue-rock used the minor 3rd - think anything in mixo - with the major 3rd as a passing note but is clearly major just the same.) Then the 2nd, b5, and maybe b13. Other notes as desired, but that selection gives a certain feel and makes the core of a song.

(NB: I play solo so this is the stuff I do to make my fingerpicked chords interesting. Flat 13, for example, mostly on the 5 chord when I want to resolve to a minor 1 chord ('coz that works so well!) - note that blues-flavoured stuff morphs between minor and major all the time. I see no reason it wouldn't work just as well for electric lead so long as your bass player and #2 guitarist or keyboard player are on board with it.)

TLDR: make a selection of about 7 or 8 notes that will make up the main feel of your song. Vary at will, but mostly stick to those 7 or 8. 

HAL9000

Despite asking the original question, for blues I’m far more likely to use major pentatonics or the BB box than to use minor pentatonics. To my ears minor pentatonics aren’t really the sound of blues; they’re the sound of blues-rock (and possibly also rock without the ‘blues-‘ prefix).

Something like the BB box notes (plus their associated bends), in my view, provide a more interesting and useful mix of major and minor tonalities and hit a certain sweet spot which pentatonics alone won’t achieve.

BillDL

That's exactly what I was saying earlier about pentatonic scales (major or minor) being a "skeleton" scale upon which you then add other notes to flavour the melody / solo so that it sounds like you want it to over whatever chords are being played underneath it.  Your choice of notes can swing the sound between major or minor depending on what chords you are playing over.

Roland

BillDL said:

...  Your choice of notes can swing the sound between major or minor depending on what chords you are playing over…

… and they can include partial bends which don’t exist in any of the major and minor scales.

HAL9000

Tannin said:

11: 4th - probably the least "bluesy" note,

Agreed. However it turns up often enough. Examples are the guitar riffs in Howlin’ Wolf’s ‘I Ain’t Superstitious’ and Little Walter’s ‘My Babe’. Might be the least bluesy note but certainly not out of bounds.

Catthan

it works bc it's got 3 chord tones of the dominant chord (flat 7) and the sharp nine (minor 3rd) which is usually bent up a half tone and becomes resonant, i.e. a chord tone major 3rd. 
bending the minor third  is a a common, 'merican thang to do when playing the pentatonic, major or minor
Easy way to create tension and release. 
if you don't bend the 3rd it will sound "ok" bc it's got the other notes, but a bit shite at the same time so when you play the minor penta from the route of the maj chord, you kinda have to micro-bend the minor 3rd. 

This, tastefully combined with the minor penta of the relative minor, creates some nice blues lickage.. 

jpfamps

This is how I was explained the theory of the blues and it's associated scale.

The blues scale contains 3 notes, the "blue" notes, that are dissonant against a major chord.

These are in order of dissonance, the b7th (as much blues employs a b7th chord on the 1 this could of course be seen as a chord tone), the b3rd and the b5th, and they give the blues it's characteristic sound.

You'll also hear these notes used in other forms of music to give some colour.

Interestingly, I used to eschew the b5th when I started playing as I did really know how to use it, however I probably use more than the other blue notes know.

However, you can't use the blues scale to derive the basic blues harmony.

One way around this, and this is technique used by jazzer musicians such as Duke Ellington and Kenny Burrell, is to use the blue notes as extensions.

For example in Kenny Burrell's Chitlins Con Carne the 1 chord is C7#9, the #9 is of course the b3rd, so the blues scale works just fine in this tune over the 1 chord.

In Midnight Blue, which is in Fm, the 5 chord is C7#9b13. The #9 (Eb) and b13 (Ab) are the b7th and b3rd from the F blues scale, so again the bleus scale is providing the extension rather than the basic chord tones.

Kenny Burrell is remarkable in his ability to employ the blues scale over a wide variety of progressions and it always sounds hip, so whilst the blues scale is certainly not the only approach you can use over a major blues, it is a perfectly valid approach.

The main issue in my view with playing blues, is that the chord resolutions / harmony aren't particularly applicable to other forms of music, so it's often difficult to translate what you learn playing blues into other environments.

I have thus come to the conclusion that country music is a much better starting point for learning the guitar than blues as there are still a ton of 3 chord songs, but the resolutions and harmony are more applicable to other musical genera.

 

GuyBoden

The Chromatic scale is best, it works over any chord, you just need to hear what notes sound good.

Listen, don't think.

carlos

GuyBoden said:

The Chromatic scale is best, it works over any chord, you just need to hear what notes sound good.

Listen, don't think.

Yeah, although if there's a popular genre which uses quarter-tones, then it's the Blues.