4-3 · Arpeggios Across the Neck

So far the rectangle and stack have done one job: playing pentatonic scales. Later modules build a wide variety of other scales on top of them. They also give you arpeggios, without requiring you to learn any new shapes.

An arpeggio is the notes of a chord played one at a time. In 4-2 you learned to read the interval of every note in and around the rectangle and stack, so you already know where the chord tones are. The only work left is picking them out.

The chord tones inside the shapes

A minor triad consists of the root, the ♭3, and the 5, and all three live inside the minor shapes. In the minor stack, the root is the upper note on the middle string, the 5 sits directly below it on the same fret, and the ♭3 is on the top string, two frets toward the nut. In the minor rectangle, the root is the lower note on the upper string, the 5 is again directly below it, and the ♭3 is the other note on the upper string.

A major triad is the root, the 3, and the 5. These are the same shapes with a different root, exactly as in 3-8. In the major stack, the root is the lower note on the top string, the 5 is directly below it, and the 3 is on the bottom string at the upper fret. In the major rectangle, the root is the highest note, the 5 is directly below it, and the 3 is the other note on the lower string.

Two octaves in one position

You already know how to build an in-position shape by alternating rectangles and stacks. If you can do that, you can already play a two-octave arpeggio. You just skip the notes that aren't in the chord.

As you play these, don't think about an arpeggio shape. Think rectangle, stack, rectangle, and read the chord tones out of each one. Because you can build an in-position shape from any root on any string, this works from any root anywhere on the neck. When a shape crosses the warp, the chord tones shift with it, the same way the whole shape does.

The stack pathway

Back in 3-5 we followed stacks diagonally. Every stack spans one octave, so a new stack starts where the old one ends, and for arpeggios that means every stack gives you one octave of the chord. In every stack, it is the same three notes in the same three places: 5, root, ♭3 for the minor triad, or 3, 5, root for the major. Slide up to the next stack and do it again.

Notice how the warp lands inside the top stack. The B and E string notes shift up a fret, and the chord tones come along for the ride. The second stack pathway, through the bottom of Form 3, the middle of Form 4, and the top of Form 5, works exactly the same way.

The rectangle pathway

The rectangle pathway works too, with a bonus. Playing the scale along rectangles meant adding a connecting 4 between them, because a rectangle doesn't quite span an octave. The triad doesn't need it. Three of the four rectangle notes are chord tones, and the next rectangle picks up exactly an octave higher.

Beyond the triad

Everything so far has been triads, but the method works for most chords.¹ If you can name the intervals, you can find the notes.

Take a dominant seventh: a major triad plus a ♭7. In 4-2 we found a ♭7 inside a seventh-chord voicing by going one fret above the 6, and the same move works here. In the major shapes, the 6 is one of the notes we've been skipping, and the ♭7 is one fret above it. That is one note outside the shape, so it's a little more to keep track of, but it's a small step on top of what you already know.

A minor seventh is a minor triad plus a ♭7, and the ♭7 is already inside the minor shapes, so you never have to leave the pentatonic. Diminished and augmented triads are one fret away as well: move the minor triad's 5 down a fret for diminished, or the major triad's 5 up a fret for augmented. Module 7 builds all of these chords properly, from the scale up. For now, the point is that any chord you can spell, you can play across the neck this way.

Exercise 4-5: Pick one chord, A minor or C major to begin with, and set up a drone on its root. Find every location of that root on the neck (there are twelve on a 22-fret guitar), build the in-position shape around each one, and play the two-octave arpeggio up and down. Don't skip the awkward positions. Where the rectangles and stacks sit across the warp or at the edge of the fretboard is exactly where the practice is needed.

Exercise 4-6: Pick a diagonal pathway and run the same arpeggio from the bottom of the neck to the top, stacks first and then rectangles. Start slowly, and say the interval names as you play them if that helps. The goal is to see the chord tones inside the shape, not to get through it quickly.

Exercise 4-7: When the triads feel steady, add the ♭7 and do the same thing with C7 or Am7.

As always, treat these as starting points. Change the chord, change the pathway, change the direction, and make up your own variations.

The rectangle and stack show you what is inside a scale, and that includes its chords. You can find the roots by name, read the intervals around them, and pull chords out of the shapes. Module 5 applies all of that to the major scale and its modes.