Ralph's Cycle of Thirds

Nov12,02

I was doing a diatonic scale exercise from a magazine (?BP, Adam Nitti?) . The exercise was to play 3 notes from the scale, then skip the next note and move to the next string for the next 3 notes, on up the neck and then back. And to make it interesting, change the starting note to a different scale degree , thereby running through all the modes. I had a heck of a time remembering what was what and which was where. But there seemed to be some order to it. One night I couldn't sleep and I came up with this diagram. It helped a lot. I asked some friends who have a pretty good music theory background and they never heard of it. So I'm writing it up and sharing it in the hope that maybe someone else will find it useful. I call it the Cycle of Thirds.

Cycle of thirds Septogram

Each point in the septogram ( seven points ) is a group of 3 consecutive notes in a diatonic scale. For example, if the scale is C major, then 123 would be CDE, 345 would be EFG, etc.

The 3 notes make up a thing I call a "Triple". You could also maybe call it a 3-triad, if you call the usual triad a 5-triad. You can't call it a triad because a triad (5-triad) is a chord using the 1,3,5 notes of a Fifth interval. It's not a triplet, which is a group of any three notes played in the time interval of a quarter note. A triple, or 3-triad, is the three notes of a Third interval.

There are 3 kinds of triples or 3-triads; Major, odd minor, and even minor.

The major triples correspond to the major thirds. They consist of 3 notes with wholestep - wholestep between them. In the key of C you have C (the 1-triple) , G (the 5-triple) and F (the 4-triple). CDE, GAB, and FGA all have wholestep wholestep intervals.

The odd minors (3,7 triples) have halfstep - wholestep intervals. The even minors (2,6 triples) have wholestep - halfstep intervals

So there you have it. If you look at the diagram, you'll see the major triples on the points of the triangle. The odd minors are on the right side of the trapezoid and the even minors are on the left. It's pretty easy to visualize.

If you go around the diagram from point to point you have intervals of thirds clockwise or sixths counterclockwise. If you go around skipping one point each jump you have fifths clockwise and fourths counter clockwise. The fifths, as usual, each contain a major and a minor third.

Some of my music buddies thought this was pretty cool. Others thought it was a big "so what" . I think the biggest advantage is that if you can connect where you are on the fretboard with where you are on the diagram, it helps you know where the next notes in a diatonic progression would be. Let me know if you find it interesting or useful , or if you've seen something like it before, or if you think I need to get a life. email me (Ralph) at twanger@together.net .