David Gilmour Solo Breakdown: Another Brick in the Wall

In this lesson, I take a deep dive into David Gilmour's iconic "Another Brick in the Wall, Pt. 2" solo. I think this is one of his greatest solos, in large part because he combines two simple ingredients into something much more than the sum of the parts.

The PDF lesson is available above, and Silver members get the full written version on this page along with the backing track player below. Enjoy!

How to solo over: “Another Brick in the Wall, Part 2”

Although David Gilmour’s solos on Pink Floyd’s “Comfortably Numb” may be more widely celebrated, his solo on “Another Brick in the Wall, Part 2” from the same album is equally good and very much worthy of study. The solo is played over a modal chord progression that defies the most straightforward analysis, but there’s an easy solution that makes it a lot of fun to solo over. In addition, understanding the process of determining which scale to use and which notes to target is well worth the effort. This lesson focuses on these steps.

This lesson assumes some basic familiarity with using a circle of fifths chart to find the key of a song, using rectangle and stack shapes to play pentatonic scales, and the basic idea of triad chord tone targets overlaid on the pentatonic rectangle and stack. I have tried to make this lesson followable without a lot of background, but if it gets confusing, you can refresh your memory via the lessons linked above. If you don’t have access to Improv 101, you can use this lesson to learn about chord tone target overlays.

Chord progression analysis

Many common chord progressions are diatonic, meaning that all of the chords can be derived from the same parent major scale.¹ A modal chord progression that is also diatonic uses chords from a parent major scale, but doesn’t use the root of the major scale as the tonal center.

Most of “Another Brick in the Wall, Part 2” is in the D Dorian mode, which is built from the notes of the C major scale. How do we know that? The verse of the song is played over vamp built around a D minor triad, and the chorus uses G, Dm, F, and C chords, keeping D as the tonal center.

Whenever the chords from a song fall into three adjacent wedges on a cycle of fifths chart, the parent major scale is the major key from the middle wedge, which in this case is C major. When a different note is used as the tonal center, we can determine the mode by finding that note’s position in the wedge.

Relative positions of the modes in the circle of fifths.

In this case, the Dm chord corresponds to the Dorian mode.

So far, so good.

Throughout the solo, the bass plays a repeated figure centered on D, even as the chords change. This is a classic way to achieve a modal feel:

Bass vamp for “Another Brick in the Wall, Part 2”.

The keyboard starts with 8 bars of Dm, then alternates between G/D and Dm. Whenever you see a “slash” chord like G/D, what comes before the slash is the name of the chord, and what comes after is the bass note. So G/D is just a G major triad with D (in this case, the fifth) in the bass. After alternating G/D and Dm four times, the keyboard plays C/D (technically, this creates a Cadd9 chord), then B♭/D (here, D is the third of the chord). It then transitions back to C/D and ends on Dm.

Here’s the whole progression:

The B♭ major triad is outside the original D Dorian key, which creates some ambiguity.

With this chord progression, we can account for three of the four chords (Dm, C, and G) as D Dorian, or account for Dm, B♭, and C as D Aeolian (the relative minor key of F major), but there is no single key that accounts for all four chords.

The good news is that there’s a scale that works for both of these keys, which means we can use it over all five chords.

Minor hexatonic scale to the rescue

The minor hexatonic scale is a minor pentatonic scale with one note added—the major 2nd. Hex-atonic just means six notes, which is one more than pent-atonic.

This is easy to visualize on a single string:

In the rectangle-and-stack framework, we can just add the major second to the rectangle and stack.

If you’re familiar with my Hidden in Plain Sight method for playing major scale modes, this is the same as the Dorian or Aeolian mode with the 6th left out.

Gilmour may not have thought about it this way, but it turns out that his solo fits entirely within the D minor hexatonic scale.

One of the coolest things about the minor hexatonic scale is that it sounds slightly ambiguous. It fits into both Dorian and Aeolian contexts and floats somewhere in between them. It has more flavor than a basic minor pentatonic scale, but it still doesn’t fully pin down the tonality. Avoiding the 6th scale degree preserves that ambiguity—and it sounds really cool.

Finding target notes

When improvising, it’s not enough to know what scale to use. Sure, if your ears are good, you can make it sound pretty good, but a good improviser always knows what chord they’re about to change to and where to find the notes of that chord in and around the scale.

So let’s look at our four chords in turn. For this part, we’ll use note names rather than scale degrees. I’ll circle back to talk about why we aren’t using Nashville notation here in a moment.

Here is the underlying scale:

We can overlay triad shapes on the rectangle and stack to find target notes for each chord. Here they are for Dm:

Notice that the notes of the Dm triad are all notes of the underlying Dm hexatonic scale. All of them, therefore, make excellent target notes.

Two of the notes of the G major triad lie inside the hexatonic scale, and those make excellent targets for your improvisation. You could also choose to target the B note, but doing so will firmly establish a Dorian sound. Gilmour avoids this note, which preserves the ambiguity of the hexatonic scale. I encourage you to experiment with using the B note both as a passing note and as a target and see what you think.

All three of the notes of the C major triad lie inside the hexatonic scale, and all three make great targets in your improvised lines. It sounds especially good to hit the E note over the C triad, both because it’s the 3rd of the chord and because it’s the only note in the scale that isn’t also part of the underlying pentatonic scale. To reach the G note in the rectangle, you can bend the uppermost note up a whole step.

The B♭ triad has the potential to snap us out of the song’s primarily Dorian context, so we should treat it with a bit of caution. The root of the triad is the minor 6th in the key of D minor, which does not fall inside our hexatonic scale. You can experiment with targeting the B♭. I kinda like it. It’s the root of the chord, so it fits perfectly, but it’s not in the original key, so it’s a little unexpected. The other two notes of the triad are also very solid targets to play over this chord.

Why not use Nashville notation?

You may be wondering why the discussion in the last section avoided using Nashville notation. This explanation may be a little hard to follow, and for that I apologize. The short answer is that the way I presented it in this lesson is less confusing than the way I personally use (some would say abuse) Nashville notation for a chord progression like this.

My previous lessons on chord tone overlays² have always been based on an Ionian or Aeolian context.

In those contexts, the root of the major pentatonic scale corresponds to the root of the I chord, and the root of the minor pentatonic scale corresponds to the root of the vi chord. Those are the most common modal contexts, so memorizing the Nashville number triad overlays for them gives you outstanding bang for your buck.

Here, in a Dorian context, if we use Nashville notation correctly, the root of our minor pentatonic scale corresponds to the root of the ii chord, and the triad overlays for the Nashville numbers lie in different locations than they do in the Ionian/Aeolian context. I think this is needlessly confusing.

Rather than memorize a new set of overlay positions for the Lydian/Dorian context (and yet another set for the Mixolydian/Phrygian context), I prefer to abuse the Nashville notation slightly and reference it to the root of the major pentatonic scale.

If we do that, since our underlying minor pentatonic scale is D minor, our underlying major pentatonic scale would be F major (the relative major of D minor), and we would need to think of all of the chords relative to F major.

In that context, Dm would be labeled as the 6- (six minor) chord, C is the 5 (five major), G is the 2 (two major), and B♭ is the 4 (four major). If you know the Ionian/Aeolian overlays and you think of the chords this way, you already know the overlays for Dm, C, and B♭. The only adjustment we need to make is to change the 2 chord from minor to major.

These are the targets I like to use when I improvise over “Another Brick in the Wall, Part 2”:

Give this approach a try and let me know what you think!