A Case Study in Rock Harmony

[Em7]

I covered the 1, 4, 5 chord progression in detail a couple of weeks ago in the “Small Victory” thread. I have been revisiting a few songs that I have not played in over thirty years that are not based on the 1, 4, 5 chord progression. I would like to share an analysis of one of the most common non-1, 4, 5 progressions that was used in seventies rock; namely, the 1, b7, 4 progression (b7 means the seventh chord in the key is lowed by a half step or one fret in guitar terms). This progression was used in southern rock tunes such as “Sweet Home Alabama” by Lynyrd Skynyrd and “Can’t You See” by the Marshall Tucker Band. It was also used in “Thank You” by Led Zeppelin and “Mr. Fantasy” by Traffic.

The chord progression to “Sweet Home Alabama” and “Can’t You See” is D (1 chord), C, (b7 chord) and G (4 chord). The main difference between these songs is that “Can’t You See” releases back to the tonic (1 or root) chord D whereas “Sweet Home Alabama” hangs on the subdominant (4) chord G. Many rock guitarists believe that both songs are in the key of D major; however, neither song is in the key of D major, as the chord C major does not appear in the key of D major. The notes in D major are D, E, F#, G, A, B, and C#.

With the above said, how do we determine the key for these songs? The key to understanding the musical key in which these songs are written is the b7 chord C. If we rearrange the chords D, C, and G, we realize that they are the 1, 4, and 5 chords in the key of G major. The notes in the key of G major are G, A, B, C, D, E, and F#. As one can clearly see, the musical keys G major and D major only differ by one note. The chords in the key of G major are G, Am, Bm, C, D, Em, and F#dim(F#m is often used as a substitute). The chords in the key of D major are D, Em, F#m , G, A, Bm, and C#dim (C#m is often used as a substitute).

Now, anyone who has seen the Marshall Tucker Band play “Can’t You See” is probably questioning my sanity.

The guitarists clearly use what looks like the B minor pentatonic pattern in the solos. As I covered in the “Small Victory” thread, B natural minor is the relative minor key of D major; therefore, B natural minor contains the same notes as D major.


D Major (Ionian mode)

B Natural Minor (Aeolian mode or simply Bm)

The reason why what appears to be a key assignment mistake works is because the pentatonic scale is missing two notes (one of which is the note C#). The missing notes are numbered 4 and 7 in the major pentatonic and 2 and 6 in the relative minor pentatonic.


D Major Pentatonic

B Minor Pentatonic

How can a song start on chord other than the root chord for the key? Making a note other than root note in a musical key a song’s tonal center is what is known as a mode.

When compared to the major scale (Ionian mode),

• Starting on the 2nd scale degree and playing to the 2nd scale degree one octave up or down is Dorian mode.

• Starting on the 3rd scale degree and playing to the 3rd scale degree one octave up or down is Phrygian mode
• 

Starting on the 4th scale degree and playing to the 4th scale degree one octave up or down is Lydian mode
• 

Starting on the 5th scale degree and playing to the 5th scale degree one octave up or down is Mixolydian mode
• 

Starting on the 6th scale degree and playing to the 6th scale degree one octave up or down is Aeolian mode
• 

Starting on the 7th scale degree and playing to the 7th scale degree one octave up or down is Locrian mode

If we examine the notes in the key of G, we see that the fifth note is D; therefore, “Sweet Home Alabama” and “Can’t You See,” are in D Mixolydian mode, which contains the same notes and chords as the key of G. The solos in “Sweet Home Alabama” are in the key of G major with a little E minor tonality thrown in for spice.

G Major (Ionian mode)

E Natural Minor (Aeolian mode)

If we examine the pattern for B Phrygian mode, it becomes clear why we can solo in B minor pentatonic over the progression to “Can’t You See.” B Phrygian contains the same notes as G major, and all of the notes in B minor pentatonic are in B Phrygian (B minor pentatonic is what is known as a proper subset of B Phrygian in set theory terms). B Phrygian has the same note interval relationship to D Mixolydian as the natural minor (Aeolian mode) has to the major (Ionian mode); therefore, we can play D Mixolydian in the B Phrygian pattern just by starting on the same position in the pattern that we do when playing D major in the B natural minor/D major pattern. Playing the extra notes in B Phrygian allows us to pick up the 4th and b7th notes in D Mixolydian, which are the root notes for the chords G and C.


B Phrygian





D Mixolydian

Finally, is it possible to solo to a D, C, and G progression in D minor pentatonic? Well, it is possible, but there is a catch. D minor pentatonic contains a minor 3rd instead of a major 3rd (F instead of F#). This note has to be handled with care because it is a half of a step down from the parallel note in D Mixolydian. D minor pentatonic is the relative minor pentatonic of the key of F major. The notes in F major are F, G, A, Bb, C, D, and E, which makes the notes in D minor D, E, F, G, A, Bb, and C. As the minor pentatonic scale is missing the 2nd and 6th notes from natural minor scale, D minor pentatonic contains the notes D, F, G, A, and C, which gives us the rote notes for the cords D, C, and G, but the F note can be problematic.


In closing, if one takes anything away from this discussion, it should be that a 1, b7, 4 chord progression is a Mixolydian mode chord progression, which means that the musical key is seven half steps down or five half steps up from the root note of the root chord in the progression. Finding the musical key of a song is critical to soloing in key.

 

[JustRob]

Thanks for sharing. I wish I could say I truly understand all this, but once you start talking Ionian, Aeolian, and Phrygian, it's all Greek to me (pun intended).
I'm going to keep at it. Maybe eventually I'll be able to connect the pieces I have together.
Thanks again.

 

[jlogicalor]

I understand the 1,4,5 progression and the minor pentatonic scale, but the rest makes my head spin.

 

[Em7]

I worked with this stuff for a long time before it made sense because music has been little more than a hobby for many years. Music theory is one of those things that just eventually clicks if one gives it enough time. The first thing that one needs to do is to gain a firm grasp of the difference between a half step (the distance spanned by one fret) and a whole step (the distance spanned by two frets). Not just from an intellectual point of view, but from an ear point of view. One needs to be able to feel and hear the difference between a half step bend and a whole step bend. It's a muscle memory and ear thing. After these distances become second nature, one can start working on intervals, which is the spacing between the notes in a scale. As I mentioned in the "Small Victory" thread, the only interval pattern that one needs to commit to memory is "WWHWWWH" (where the letter "W" denotes a whole step between notes and the letter "H" denotes as half step between notes), as it is the interval pattern for the major scale. All of the other scales/modes are derived from the major scale. The major scale sounds like do, re, mi, fa, sol, la, ti, do. The first "W" in the pattern is the distance between do and re, which is a whole step. The second "W" in the pattern is the distance between re and me, and so forth. I know that the tune is cliché (no pie please), but "Do Re Mi Fa" from the Sound of Music is a good tool to use when learning melody because it's a musical earwig (like that blasted Disney song "It's a Small World"). The melody line is usually encoded in the vocal line in non-instrumental songs.

Play the D major scale pattern shown in my earlier posting and listen to the notes. They sound like do, re, mi, fa, sol, la, ti, do. All of the other scales and modes are just derivations from this fundamental scale. Melody lines are just different patterns of notes in a scale played over a harmony. The harmony of a song is primarily encoded its chord progression.

 

[aristotle]

Boy...this just reinforces that I have no real clue. Ironically, I just got back from a gig where we played "Can't You See". I'd have sworn that I was playing the solo in D major. And I wouldn't have thought that it was a pentatonic. Whatever I was playing, it worked..... I don't play note for note on every song that we do, but I ferret out what works and it's more or less true to the sprit of the original... but I don't know why I play the notes that do..... So. EM7, do you think that most artists approach it from the sort of technical point of view that you present, or do you think that they just do what "feels right".... and it turns out that it "feels right" due to the theory? Regardless, great post, and I'm going to noodle over what you've presented....

 

[László]

Boy...this just reinforces that I have no real clue. Ironically, I just got back from a gig where we played "Can't You See". I'd have sworn that I was playing the solo in D major. And I wouldn't have thought that it was a pentatonic. Whatever I was playing, it worked..... I don't play note for note on every song that we do, but I ferret out what works and it's more or less true to the sprit of the original... but I don't know why I play the notes that do..... So. EM7, do you think that most artists approach it from the sort of technical point of view that you present, or do you think that they just do what "feels right".... and it turns out that it "feels right" due to the theory? Regardless, great post, and I'm going to noodle over what you've presented....

Knowledge is always a good thing. I think we can all see how that the more one knows, the more options one can reach for in one's playing "bag of tricks."

At the same time, there are folks that have a tremendous intuitive musical sense, and do certain things that folks schooled in theory do, but they go there without knowing the names of the scales, modes, etc. Just as there are "ear learners" and "eye learners" in the world of education, the same is true of musicians.

Rimsky-Korsakov said in his classic work on Orchestration that he could teach the reader everything about orchestration, and nothing about composing, because one either can, or can't, compose. I believe that a similar thought can be applied to the application of musical theory by an instrumentalist.

The very talented play instruments well, and musically, regardless of theory, though knowing theory will make them better. Those with less talent can know an awful lot of theory but may still not produce very musically listenable stuff.

But I think it's good to know things, anyway.

 

[Em7]

Boy...this just reinforces that I have no real clue. Ironically, I just got back from a gig where we played "Can't You See". I'd have sworn that I was playing the solo in D major. And I wouldn't have thought that it was a pentatonic. Whatever I was playing, it worked..... I don't play note for note on every song that we do, but I ferret out what works and it's more or less true to the sprit of the original... but I don't know why I play the notes that do..... So. EM7, do you think that most artists approach it from the sort of technical point of view that you present, or do you think that they just do what "feels right".... and it turns out that it "feels right" due to the theory? Regardless, great post, and I'm going to noodle over what you've presented....

I bet that you are actually improvising in D Mixolydian without knowing it. If you were improvising in D major, the sharp 7th would sound funny to your ears because the solos in that tune are fairly melodic.

Like all of the theory that one learns while studying engineering or computer science, music theory is a good analysis and fundamental research tool. Music theory gives one insight into why some songs just sound right while others sound like garage rock. However, all of the theory in the world is not going to make one a great guitarist. Most of the really great engineers and computer scientists that I have met in my life have an intuitive feel for their respective discipline. Learning theory merely made them better engineers and computer scientists. The same can be said about music theory. It is just a set of tools that one has to have the raw material to apply in a performance context.

Truth be told, I am not a gifted guitarist. I am a good enough guitarist who has a decent ear and a solid fundamental understanding of music. I was struck by an SUV while crossing the street at work a few years ago. The injuries that I sustained have impacted my ability to play guitar like I did before the accident, so I have focused my energy on becoming a better musician and sharing the knowledge that I have been able to gain through the years with others. I originally learned music theory on piano in college in fulfillment of a general education requirement. While I am not a pianist, music theory and formal notation map beautifully to piano. Mapping music theory to rock guitar has been hard work because rock music often breaks the rules (mostly due to its low barrier to entry). I post this information to reinforce what I have learned as much as to disseminate it to others.