Break into the box

In Hiding in Plain Sight, I introduced the mental model of “the rectangle” and how six of the seven diatonic modes can be found there. This idea provides a useful and easy-to-see pivot for going back and forth between pentatonic scales and their related diatonic modes.

Figure 1: Six of the seven diatonic modes sit comfortably inside their parent pentatonic scales.
Figure 1: Six of the seven diatonic modes sit comfortably inside their parent pentatonic scales.

“The rectangle” is useful in its own right as a place where we can easily reach every note of every diatonic mode within a four-fret span. But you may have noticed that there are seven notes in each mode, and only six in each diagram from Figure 1.

A quick examination of the diagrams in Figure 1 reveals that the fourth scale degree is missing from the minor modes, and the second scale degree is missing from the majors. Those notes are in the underlying pentatonic scales, but they sit outside “the rectangle”.

It turns out that for all of the modes, the missing note is easily reached by bending the highest note in the rectangle a full step. Easy peasy!

To make this explicit, here are the three minor diatonic modes rooted on the A note on the 5th fret of the high E string. The 4th scale degree is easily reached by bending the b3 up a full step. Note that in all of these diagrams, I have marked the tonal center in red, the other notes of the triad built on the first scale degree in blue, and the remaining notes in black (more on this in our next post):

Figure 2: The A Dorian, Aeolian, and Phrygian modes rooted on the 5th fret of the high E string.
Figure 2: The A Dorian, Aeolian, and Phrygian modes rooted on the 5th fret of the high E string.

We can do the same thing with the major modes. The 2nd scale degree is easily reached by bending the root up a full step:

Figure 3: The C Lydian, Ionian, and Mixolydian modes rooted on the 8th fret of the high E string.
Figure 3: The C Lydian, Ionian, and Mixolydian modes rooted on the 8th fret of the high E string.

Bonus: Locrian

As I mentioned in the previous post, the Locrian mode, because it has a b5, does not have a corresponding major or minor pentatonic scale. Although this is still true, the Locrian mode does have it’s own rectangle, with the root being the lowest note, and the b7 being reachable by bending the highest note up a full step:

Figure 4: The E Locrian mode rectangle.
Figure 4: The E Locrian mode rectangle.

Moving these shapes around

These rectangles are of course not limited to the top two strings. You can play them on any pair of adjacent strings. Just remember that if you choose a root on the B string, you’ll need to shift the notes on the G string one fret toward the nut.

Figure 5: A G Dorian scale.
Figure 5: A G Dorian scale.
Figure 6: An E Dorian scale straddling the G & B strings.
Figure 6: An E Dorian scale straddling the G & B strings.

Navigating from here

From any of these “rectangle” positions, you can easily switch over to 3nps or in-position scale patterns, as well as the minor and major pentatonic scales.