The Circle of Fifths

Another way to think about the pentatonic scale is using the circle of fifths.

The circle of fifths is the periodic table for the elements of music.  It’s like a clock with C at 12.  Each hour clockwise goes up by a perfect fifth (adding seven semitones).   If you go counterclockwise, you get a circle of fourths.  

At various times it’s useful to think about the names in the circle as notes, chords or keys.  As keys, each move clockwise adds one sharp to (or removes one flat from) the key signature, as shown on the figure.

The major pentatonic scales fall naturally from the circle of fifths.  The key thing to note is if you start anywhere and list five consecutive notes going clockwise you get a major pentatonic scale.   For example, if you start at C you get: c g d a e, which are of course the notes in C major pentatonic.  You have to rearrange them to get them in order.

If you add two more adjacent notes to the five in the pentatonic, one to the left of the start and one to the right of the end, you get the 7 notes of the major scale.  So you can think of C major as the union of F pentatonic and G pentatonic.

I made the above slap-bracelet picture of the circle of fifths because I couldn’t find one like it on the web. It’s more like a spiral of fifths.  Unlike a circle, with a spiral you always end up at a different place if you go clockwise than if you go counterclockwise.  I got 21 note names on the bracelet, which is as far as you can go without venturing into double sharps and double flats.   (Each of the three white keys D, G and A is sandwiched between two black keys, so doesn’t have an alternate name with only one sharp or flat.)

Compared to the typical circle of fifths, the bracelet lets you visualize the difference between, say, Bb and A#.  For any particular song you’ll almost always concentrate on a small patch of the bracelet, mostly using around 5 to 9 adjacent notes (the key or keys). When you’re playing F, C, G, Eb or Ab that’s a Bb when you get to it.  When you’re playing G# or D# or C# or F# that’s an A# when you get to it.  

The bracelet helps you avoid embarrassing errors between sharps and flats.  With the regular circle, you have to remember that if you start your scale in a sharp key, you use sharps for the black keys, for example A pentatonic is: a e b f# c#, or in order: a b c# e f#.   I went around the circle and called the note C# instead of Db because I started in a sharp key.  With the bracelet there’s no confusion -- the notes near b are f# and c#, not Gb and Db.

Next: A Diversion Into Temperament

Next (skipping tangent): The Black Keys