I mentioned in an earlier post that I use my knowledge of double stops to navigate the fretboard. Here is a little further explanation of what I mean by that.
The double stops that form intervals of fourth, a major third, and a minor third form an important framework that informs how I see the mandolin fretboard and how to navigate between different positions and through chord changes.
Sharon Gilchrist, I think, was the first person I heard call these the short, medium and long double stops and I like that way of describing them. Before hearing that I always called them by the intervals that they form, the perfect fourth, the major third, and the minor third.
The short double stop is the one that has a difference between the lower and higher strings of two frets (or one empty fret between your two fingers). That is a perfect fourth which is also an inversion of a perfect fifth and when I am thinking around the fretboard, it is mostly that fifth to root relationship that I am considering when using this double stop.
The medium double stop has a difference of three frets between the the lower and higher strings and the interval is a major third. A major third is the interval between the root and third in a major chord, and it is also the interval between the third and the fifth in a minor chord.
The long double stop is the one with a four fret difference between the lower and higher strings. This interval is a minor third. Minor thirds are sometimes played as the interval between the root and minor third of a minor chord, but they are also the interval between the third and fifth in a major chord, and the interval between the fifth and seventh in either a seventh chord or a minor seventh chord.
So, how does this all come together to help us navigate the fretboard?
One way this helps is in reinforcing our knowledge of arpeggios and giving us some redundant information that I think helps us naturally move around while playing over a single chord.
Starting with any one of the double stop positions, there is a major arpeggio pattern that uses all three double stop positions as string crossings. Each of these places at most two notes on each string. The same is true for minor arpeggios.
That gives us really three cornerstone finger position patterns to learn that I think of as similar to the CAGED system that guitar players learn.
The cyclical pattern of the double stop positions in these string crossings is small, large, medium, small … that is, if you start with a small double stop position as the crossing between the lowest two strings, the crossing between the middle strings will involve a large double stop and the crossing between the second and third strings will use a medium double stop.
Moving our double stops along a particular pair of strings has a different pattern.
On any pair of strings, taking any of the three double stop positions as two notes in a major chord, the next double stop that is part of the same chord occurs on that string pair in a pattern that follows, small, medium, large, small (until you run out of frets).
The cyclical pattern of these up the neck double stop positions is small, medium, large. This is because in each of these moves, the higher note becomes the lower note of the next double stop – fifth to root (short), root to third (medium), third to fifth (long), fifth to root, etc.
Another important observation about these double stops is the patterns for chord changes over 1 4 5 chords.
Starting with any of the short, medium, or long double stop as a part of the I-chord, a double stop that is part of the IV-chord and one for the V-chord can be found nearby using the other two double stop positions.
This gives us a way to find, from one double stop position, the nearby position for intervals that are part of the next chord in the song.
Taken together, by mastering just these three patterns in italics above, it becomes much easier to move across the strings as well up and down the neck. And since this is based on closed positions, no open strings, playing in any key becomes a lot more manageable. .
I’ll write up some tab or fret diagrams to demonstrate the three observations in italics above . (I think I’ll also make separate posts that go into a little of the interval theory that I sort of assume above.)