When Pentatonic Superimposition was first pointed out to me I had one of those “why didn’t I see that before” moments. It’s a simple idea that helps get some interesting jazzy tonality into your improvisation with very little effort.
Mark Dziuba, in his book The Big Book of Jazz Guitar Improvisation says,
One of the most exciting improvisational concepts is the idea of superimposing non-root based minor pentatonic scales over the different chord families. The idea is to choose minor pentatonic scales that contain specific chord defining pitches such a 3rds, 7ths or altered 5ths and also highlight colourful tensions like 11ths, 13ths and their alterations. Since it’s a five note scale, the pentatonic scale provides an ideal, concise and very colourful improvisational cornucopia!
To get started lets consider the F major scale.
In a major key there are 3 minor chords that have roots on the 2nd (II), 3rd (III) and 6th (VI) degrees of the scale. So, in the case of F major that’s Gm, Am and Dm. In the jazz context they are going to be minor 7th chords so that’s Gm7, Am7 and Dm7. Keep that in mind.
Playing a II minor pentatonic scale over a IIm7 chord
Typically you’d improvise over a IIm7 chord – the Gm7 in this case – using the Dorian mode but a simple G minor pentatonic will also work. If you take a look at the intervals of the notes of the G minor pentatonic in relation to the G root you’ll find the scale contains, in addition to the root, a flat 3rd, perfect 4th, perfect 5th and a flat 7th. In other words: R, b3, p4, p5, and b7.
The R, b3, p5 and b7 are the notes of a m7 chord. That leaves the p4. Now, remember that the p4 is the same as an 11 in harmonic terms so the G minor pentatonic scale includes all the notes of the m7 chord plus an extension tone – the 11.
It’s not much of a surprise to learn that G minor pentatonic works over Gm7 but the notes are very close to those of the chord so the overall effect is not very interesting. The 11 has some flavour but not much.
Playing a VI minor pentatonic scale over a IIm7 chord
If you stay in F major and take the same basic ‘box 1’ penatonic shape you’ll see it could also be played at the 10th fret, starting on the 6th degree of the scale (D). The notes are all still from G dorian so will work over Gm7. You could think of the notes as the D minor pentatonic scale but if you look at them in relation to a G – the root of Gm7 – things get a bit more interesting.
Compared to the G minor pentatonic scale we’ve lost the b3 but gained the 2. In harmonic terms the 2 is the same as a 9 so now we’ve got two chord extension tones to play with: the 9 and the 11. So, a D minor pentatonic works well over a Gm7 chord and adds a bit of extra flavour in the form of the 9.
Playing a III minor pentatonic scale over a IIm7 chord
But hang on… the good old ‘box 1’ pentatonic shape fits in nicely over the notes of the F major scale at the 5th fret too with the root note being the 3rd degree of the scale; an A minor pentatonic if you like. Again, the notes are all from G Dorian. If you look at the notes in relation to a G root we get something even more interesting.
In comparison to the G minor pentatonic scale we’ve lost the b3 and b7 but we’ve now got the 9, 11 and 13. So we’ve added a new extension note, the 13. You can see that an A minor pentatonic played over Gm7 will work – the notes are still from the Dorian mode – and we have some nice piquancy in addition to the 9 and 11 the form of the 13.
Firstly, I’ve only shown the basic box 1 pentatonic shapes for clarity but of course you can play all the notes of each pentatonic scale up and down the neck, not just in the box 1 position.
This technique – Pentatonic Superimposition – works because we play fewer notes than a full Dorian scale and can emphasise notes that would form part of a chord extension such as the 9, 11 and 13 which creates a sense of harmony
Recall that there are 3 minor chords in the major scale falling on the II, III and VI degrees of the scale. In F major – our example key – that’s Gm, Am and Dm. And what are the 3 pentatonic scales that work over the Gm7? They are G, A and D. Go figure.