Originally published July 29, 2024
Why do so many teachers tell beginning improvisers to "just use the minor pentatonic to play over the blues"? This lesson contains everything they don't tell you about that approach, and it will get you sounding bluesy in a jiffy.
What follows is the written lesson — the full contents of the PDF handout, so you can read it here or download it above.
Sometimes, it seems like there are as many approaches to improvising over a 12-bar blues as there are guitar players, but for some reason, countless guitar instructors give their beginner players a basic lesson along the lines of:
It’s almost reasonable advice. After all, a skilled guitarist can make the A minor pentatonic scale sound good over a 12-bar dominant blues.
However, these instructions are leaving out a huge fraction of what a skilled player is doing to make this approach work. It’s a case of being accurate without really being helpful.
This lesson is my attempt to fill in those blanks so that you, too, can make the minor pentatonic scale sound good over a dominant blues. This discussion will be extremely practical toward the end, but before that, we will abuse some music theory. As we go, remember that this is just one way to approach the blues, not the only way.
First, let’s define a dominant blues. It’s most often played in a 12-bar form using three dominant 7th chords. In the key of A, those chords are A7, D7, and E7. There are a few variations of the exact sequence of chords, but this is one of the most commonly played versions:
Although we say that this chord progression is “in A,” the key of A major has three sharps: F#, C#, and G#, but the A7 chord has a natural G, and the D7 chord has a natural C. Only the E7 chord is native to the key of A.
In music theory, this type of chord progression is called non-diatonic, meaning that the chords do not all come from the same parent scale. That means that theoretically we shouldn’t be able to just use one scale to improvise over the whole thing.
You might argue that we could eliminate the flat sevenths in the A7 and D7 chords and make them into major triads. That works in theory, but it doesn’t work in practice because our ears are so used to hearing this progression sound a specific way that they will hear those chords as dominant even if they aren’t played that way.
And, even if it did work, the A minor pentatonic scale would be a surprising choice because it has a flat third and a flat seventh, which are not in the A major scale.
So what key is “Blues in A” in? The theoretical answer lies somewhere in the murky grey area between the A Dorian and A Mixolydian modes. But we’re not going to think about it that way.
The minor pentatonic scale has five notes and is spelled R - ♭3 - 4 - 5 - ♭7. Here it is on one string:
The reason this scale can be used over a blues progression lies not in its notes but rather in how the chords of the blues progression relate to it. So, let’s consider each chord in turn.
A dominant seventh chord is spelled R - 3 - 5 - ♭7. If we overlay the notes of an A7 chord onto the A minor pentatonic scale, the root, fifth, and flat seventh fall on scale notes, which is a great start. They will make great target notes for our improvised lines.
However, notice that the major third of the chord is a half step away from both the ♭3 and the 4 of the minor pentatonic scale. In blues, the natural third sounds good, although perhaps a little square. When the natural third is played in the blues, it is almost always preceded by a ♭3 grace note, with either a hammer-on or slide to connect them. One of the keys to the blues sound on guitar is to play the flat third but bend it slightly sharp so that the pitch falls somewhere between the flattened and natural thirds. Many guitar players do this without even realizing it!
You’ll never see this in a theory textbook, but in your head, it’s simplest to visualize a minor 7th chord and remember to always give the flat third a little nudge. Here, it is overlaid on the pentatonic scale:
It’s a perfect fit! Here it is overlaid on the classic Form 1 A minor pentatonic scale:
The only notes that don’t fit the chord are the two Ds. We can use them as passing tones, but it makes sense to avoid dwelling on them.
To be able to play this across the fretboard and in different keys, we’ll use the rectangle and stack methodology and practice each shape in multiple positions.
When playing the minor pentatonic rectangle over the I7 chord, we can target any of the four notes as long as we remember to give a small bend to the flat third in the upper bridge-side corner.
When playing the minor pentatonic stack, we’ll want to avoid emphasizing the 4th since it will clash with the I7 chord, but the other notes are great targets. Just remember to bend the flat third a smidge!
We have a slightly different challenge when it comes to the IV7 chord.
The root, fifth, and flat seventh all fall nicely onto minor pentatonic scale tones. If we are willing to limit ourselves to targeting those notes, we can continue to use just the minor pentatonic scale.
But that rub between the flat and natural third is so essential to the blues that it’s worth learning where to find the ♭3 of the chord.
The ♭3 is one semitone from a scale note, and it’s reachable from both the rectangle and the stack.
When playing the rectangle over the IV7 chord, target the upper corners to tag the 5 or ♭7, and find the ♭3 one fret above the 5th of the original minor pentatonic scale. That note is now the 9th of the IV7 chord, so it’s not really an avoid note, but it’s the ♭3 with a little bend that will make it sound bluesy.
Playing the stack is similar, except that the ♭3 is obviously in a different spot.
The V7 chord is slightly more challenging.
Although the 1 and ♭7 fall on scale tones, the 3 and 5 of the V7 each lie one semitone away from the minor pentatonic scale.
We can fix one of those problems by switching to visualizing the minor seventh variant of the dominant 7 chord as we did before.
The 5 is still a problem, and we should try to avoid the ♭3 of the minor pentatonic scale because it has become the ♭6 of the V7 chord, which won’t sound great.
When playing the minor pentatonic rectangle, avoid the upper bridge-side note and give the lower bridge-side one a nudge upward.
When playing the stack, the ♭3 is on the middle string, and we should avoid the ♭6 in the upper nut-side corner.
To summarize, we’ve learned that we can play the minor pentatonic scale over a dominant blues, but each chord in the chord progression provides a slightly different challenge because different chord tones will clash with the scale.
We can simplify things by visualizing the minor versions of the dominant chords in the progression and always bend the ♭3 of each chord just slightly sharp.
Using the rectangle and stack methodology minimizes what you’ll need to memorize to be able to do this across the entire fretboard. Here is everything discussed in this lesson, condensed into one diagram:
Find a 12-bar blues backing track in any key. Start by focusing on just the rectangle and practice targeting chord tones on each chord change. Stay in one position for a while and work on making interesting phrases by using hammer-ons, pull-offs, slides, bends, and ghost notes, by varying your rhythm, leaving space, and being mindful of which notes you emphasize and how they relate to the chords. This is a lot to think about, which is why it makes sense to start in a small area of the fretboard.
When that becomes comfortable, switch to the stack and repeat the process. Practice playing the stack positions that fall across the warp. Each of them will lead you to different licks based on how your fingers relate to them.
When you can make good phrases using each shape in multiple locations, practice combining them into one of the five pentatonic positions at a time. Do this for one of the five positions until you are comfortable, and then move on to the next one.
And then, finally, practice moving all over the fretboard. Take advantage of the diagonal pathways that connect the stacks. Many blues players only play in Form 1 plus the upper and lower stack extensions, so be sure to explore that area in depth.
I don’t recommend memorizing each position of the pentatonic scale individually, but when you’re starting out, it can be helpful to have everything laid out in front of you. You may also find these diagrams useful as a way to check your understanding of the previous discussion.
Blues in A
A · 90 BPM · 12 chords · 32.0s loop
The twelve-bar form at 90 BPM. The board holds one A minor pentatonic scale throughout, the way this lesson does, and marks every tone of each chord rather than the triad alone — so the ♭7 you have been reading about is on the fretboard in front of you as the chord goes by. Drag across any two bars to loop just that change, and slow the tempo while the sevenths are still new.
Happy improvising!
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