Pentatonic and Blues Scales

We've spent this part building seven-note scales and moving one or two of their notes. To finish, let's do the opposite: take some away. By keeping only five notes, you get scales so safe that you can play the notes in almost any order without anything rubbing. These are the pentatonic scales, from penta, Greek for five. You already know them without realizing it: play only the black keys of the keyboard, and you're playing a pentatonic scale.

Five black keys

Try the experiment first. Listen to a melody improvised on the black keys only, over a bass that holds F♯3.

Even improvised without thinking, the melody never sounds wrong. You can see why on the grid: between two neighboring black keys, there's always at least a whole step. The major and minor pentatonic scales contain no half steps, so no pair of neighboring notes that rub. It doesn't contain the tritone either, the six-half-step gap that is the most unstable interval in the major scale, and which we'll study along with the intervals.

The major pentatonic

Take the C major scale and remove the two notes that form a half step with their neighbor, F and B. That leaves C, D, E, G and A: that's the C major pentatonic. It keeps degrees 1, 2, 3, 5 and 6 of the major scale. Its pattern becomes: whole, whole, step and a half, whole, step and a half.

It keeps the bright color of major, since the third degree is still there, but without any tension. The black keys from earlier formed exactly this pattern starting from F♯: F♯, G♯, A♯, C♯ and D♯. That was the F sharp major pentatonic.

The minor pentatonic

You remember relative keys: A minor has the same notes as C major. The same is true of pentatonics. Keep the five notes C, D, E, G and A, but take A as home: you get the A minor pentatonic, A, C, D, E and G. Compared with the A minor scale, the second and sixth degrees, B and F, have been removed. What's left are degrees 1, 3, 4, 5 and 7 of the minor scale.

Its pattern starts with a big step: step and a half, whole, whole, step and a half, whole. It's one of the most widely used scales for improvising, from guitar solos to synth leads. Listen to the two pentatonics one after the other: same notes, but not the same home.

Why it's so safe for improvising

Since no note rubs against its neighbor, you can string together, repeat or stack the notes of a pentatonic in almost any order. It also fits most of the chords in its key. In A minor, the A minor pentatonic works without any trouble over A minor, C major, D minor or F major chords: none of its notes sounds really wrong, and some just add a color, like a seventh or a ninth.

The trade-off is that a pentatonic has less character than a seven-note scale. It has no leading tone pulling toward the tonic, and no characteristic note like the modes. When you're after a specific color, you'll need to go back to seven-note scales. When you want a simple, singable melody with no accidents, the pentatonic is the best place to start.

The blues scale and its blue note

Now add one note to the minor pentatonic: the one between the fourth and fifth degrees. In A, that's E♭, squeezed between D and E. You get the blues scale: A, C, D, E♭, E and G. The added note is the most famous of the blue notes, those “in-between” notes that come from the blues.

This note rubs, and that's intentional: with it, the scale gets two half steps back, from D to E♭ and from E♭ to E. You don't land on it. You slide through it on the way from D to E, or you linger on it for a moment to create a tension that releases onto E. Listen to a phrase that uses it that way.

In sung blues or blues played on guitar, musicians often place these notes a little above or a little below the exact row. In your software, you can imitate that looseness with a glide or a pitch bend that starts on E♭ and arrives on E. The notes C and G, that is, the third and seventh degrees of the minor scale, also become blue notes when you play them over an A major chord, which gives that color that's happy and sad at the same time.

You now have every scale a producer needs day to day. In the next part, we'll measure precisely the distance between two notes, the intervals, which are the building blocks of every chord.