Demystifying Music Theory Part 2

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June 11, 2013 by admin

I’ve heard some musicians refer to a concept known as the Circle of 5ths (or even the Circle of 4ths)…what is it and how is it applied?

What exactly are modes?

I know what major and minor chords are, but what are Sus, Dominant, and 7th chords all about?


DEEPER CONNECTIONS – If you read my introduction to music theory, then you should realize that nothing in music (scales, chords, etc.) can function in isolation.  All concepts of music theory are connected together in order to form a logical and coherent system.  We can take this a step further and explore the relationships between the 12 notes of western music.  The names for each of the 12 musical notes (starting with ‘A’) are as follows:

A,  A#,  B,  C,  C#,  D,  D#,  E,  F,  F#,  G,  G#  (# = sharp)

As mentioned in my introduction to theory, if you play each note in consecutive order, then you have run through the chromatic scale.  But the chromatic scale is a bit too random and unpleasant sounding to make any strong connections between these 12 notes.  So, as with the intervalic system, we will enlist the help of the major scale.

If we play the major scale (starting with ‘C’), we get the following notes:

C,  D,  E,  F,  G,  A,  B,

Notice anything interesting?  There are no sharp (#) notes when the major scale is being played in the key of ‘C’.  The important concept to understand here is how I use the term ‘key’.  In my introduction to theory, I explain that the tonal center of a scale is the focal point of resolution (the 1 note of the interval formula).  When discussing the major scale’s tonal center, we can refer to it as a ‘key’.  This term gets tossed around a lot these days and is often misused.  For example, if a guitarist wants to improvise with a live band at a bar, he would probably ask, “What key do you want to play in?”  One of the players in the band might reply, “Let’s do it in A minor blues.”  Using the term ‘key’ in this way is definitely more succinct than asking “What tonal center do you want to play in?”  However, according to some strict music theorists, this is a misuse of the term.

Only the tonal centers of the Major Scale are referred to as a ‘key’.  This brings us to the introduction of what is known as the Circle (or Cycle) of 5ths.





CIRCLE OF 5THS – Don’t be intimidated by the image you see above.  It is simply a system based upon the relationships I alluded to earlier that are found between the 12 different ‘tonal centers’ of the Major Scale (Just to clarify, there are only 7 notes in the Major Scale, but because there are 12 notes in Western Music, each note can play the role of ‘tonal center’ in a given situation)

So let’s look again at the notes of the Major Scale in the key of ‘C’

C, D, E, F, G, A, B

As mentioned, there are no sharp (#) notes in the Major Scale when played in the key of ‘C’. Every other ‘key’ will have either a certain amount of sharp notes or flat (b) notes (I’ll address flat notes a little later).  So the key of ‘C’ is unique in that it contains only natural notes.  Natural notes are notes without a sharp or flat symbol attached to them.  The symbol for a natural note looks like this:





You won’t see the natural symbol as often as you’ll see the sharp or flat symbols, but it will pop up when accidentals are notated (more about accidentals later).

So our starting point in the Circle of 5ths is the key of ‘C’.  What happens when we select the 5th note in the ‘C’ Major Scale to be our next tonal center?  We get the Major Scale played in the key of ‘G’.  The notes of the ‘G’ Major Scale are:

G, A, B, C, D, E, F#


The key of ‘C’ and the key of ‘G’ share all of the same notes in common, except for one.  And this new note just so happens to be sharp.  Now let’s take the 5th note of the ‘G’ Major Scale and use that as our next tonal center.  This will be the Major Scale in the key of ‘D’ and its notes are:


D, E, F#, G, A, B, C#


You might already be noticing the pattern here.  The main tenet of the Circle of 5ths system is: (starting with the Key of ‘C’) by using the 5th note of the scale to build your next key, two important results will be consistently produced;

1.)  The new ‘key’ will always contain the same notes as the previous key, except for one new note.

2.)  This new note will always be a non-natural note (sharp or flat).


Visually, the Circle of 5ths can be thought of as a ‘clock’ which produces the aforementioned results by moving clockwise, starting from the top, through the Circle.

There are a few more interesting patterns that arise (the new note being introduced is always the Major 7th interval of that scale) but the two that I outlined above are at the foundation of the system.  At this point, you might be asking yourself these two questions; When and how do the flat notes come into play?  How do I actually apply this system to my playing?

The primary usage of this system is for when a person is reading sheet music (written music notation).  Instead of notating every individual occurrence of a sharp or flat note, the amount of sharp/flat notes found within the given key is simply notated at the beginning of the piece.

If you look at the Circle of 5ths image, you will notice by each key that there is a small picture of the treble clef with a certain amount of sharps (#) or flats (b) next to it.  This is known as the key signature.  It indicates to the music reader that a pre-established set of notes will be either sharp or flat in a given piece.  If you want to be proficient at sight reading then you would need to memorize both the number of sharp/flat notes within each key and the specific notes that are sharp or flat.

To illustrate this example visually, I have displayed the key signatures for both the key of C and the key of G respectively:

















In the first image, the lack of a sharp or flat symbol next to the Treble Clef indicates that the subsequent piece will be played in the key of C, where there are no instances of non-natural notes.  

In the second image, where you see one sharp symbol next to the Treble Clef, the piece would be played in the key of G, where the F# is the one non-natural note.

This pattern holds true for the entire Circle of 5ths system.  Now, what if you are reading some sheet music and you notice that an individual note has a sharp or flat symbol next to it?








These notes are called accidentals.  An accidental is any note which is not apart of the family of notes found within a particular key signature.

For example, if I wrote a song in the key of ‘G’ then every note that I use should come from the following options:

G, A, B, C, D, E, F#

In this case, there is no need to notate a sharp symbol every time an F note is played in my song, because it is already assumed to be an F# by virtue of the key signature.

This is also known as being diatonic, meaning “within the key”.

But if I want to add some dissonance in my song, then I might throw in a G#.  This note would need to be accompanied by a sharp symbol to show the reader that it is an accidental.


FLAT NOTES AND THE CIRCLE OF 4THS – Now let’s discuss what role the flat (b) notes play in this system.  There are two additional rules of the Circle that need to be looked at:

1.)  If playing diatonically (no accidentals) then the same letter note cannot be notated in two different ways within the same key signature.  (F and F# for example)

2.)  Sharp and flat notes cannot be mixed together in the same key signature

These don’t seem like hard rules to follow, until you arrive at the key of F#.  If I played the Major Scale, with F# being my tonal center, the following notes are produced:

F#, G#, A#, B, C#, D#, F, 

By containing both an F and F#, there’s obviously a conflict within this key.  So let’s try it this way:

F#, G#, A#, B, C#, D#, E#

Well this version follows the rules, but only when you introduce an E#.  But is E# really a note?  Sort of.  You will see it notated in some books, but it is uncommon.  The relationship between these two notes (F and E#) is what’s known as enharmonic.

Similar to the concept of compound intervals (which I mention in my introduction to theory) this is, again, an issue of semantics.  An F and an E# are enharmonically equivalent, meaning they’re the same exact musical notes but are notated differently depending on the circumstances.  In order to avoid notating an E# while still adhering to the rules, we need to utilize the flat notes.  

Every sharp note (plus ‘B’ and ‘E’) has an enharmonically equivalent flat note.  I’ll list them below:

A sharp = B flat

B         = C flat

C sharp = D flat

D sharp = E flat

E         = F flat (rarely notated)

F sharp = G flat

G sharp = A flat

Let’s try and list the notes of an F# Major Scale one last time, but now we will refer to it as a ‘G flat’ Major Scale, and all previous instances of sharp notes will be re-notated to their corresponding flat notes:

Gb, Ab, Bb, Cb, Db, Eb, F

This seems to work a little better.  The flat notes are added to each successive key in almost the same way the sharps are added, except that we start at the top and move ‘counterclockwise’ through the Circle by selecting the fourth note from the scale to build the next key.

We can call the ‘flat’ side the Circle of 4ths.

If we look at the Major Scale in the key of ‘F’ (the 11 o’clock position in the image) we get the following notes:

F, G, A, Bb, C, D, E

If we take the 4th note and build our next key, we have the Major Scale in the key of Bb which consists of the following notes:

Bb, C, D, Eb, F, G, A

So there you have it.  The key of ‘C’ is the starting point and, depending on which direction you travel, you can refer to it as either the Circle of 5ths (clockwise) or the Circle of 4ths (counterclockwise).

RELATIVE MINOR – When you look at the Circle of 5ths image, you might also be wondering what role the lowercase green letters inside the circle play? Well these green letters indicate what the Circle of 5ths would look like if we applied the system to the Minor Scale.

Earlier I said that, technically speaking, you should only use the ‘key’ terminology when discussing the Major Scale.  This is still true, but in today’s musical climate, the Minor Scale is just as important as the Major Scale.  Saying something like, “let’s play this in the key of E minor” is considered widely acceptable.  But the interesting part is the relationship between the red letters on the outside of the circle (the Major keys) and the lowercase green letters on the inside of the circle (the minor keys).

Let’s look again at the notes of the Major Scale in the key of ‘C’ :

C, D, E, F, G, A, B

Now let’s see what happens when we play those same seven notes, but use the 6th note in the scale (A) as our new tonal center.  Instead of it sounding like a happy sounding Major Scale in the key of ‘A’, we end up producing the Minor Scale.  This is called the relative minor.  

There is an important difference that needs to be emphasized between the Circle of 5ths system and the Relative Minor concept; In the Circle of 5ths, we take the 5th note in the scale and intentionally build a Major Scale with that 5th note being the new tonal center.  This means that we can introduce new notes into the picture.  However, with the relative minor, we are using the 6th note of the Major Scale to be the new tonal center but maintaining the same seven notes.  Remember, for any two scales to have a ‘relative’ relationship, they must contain the same exact notes, while only shifting the tonal center.

In fact, every key of the Major Scale has a relative minor scale hiding within it.  So the green letters found inside the circle indicate the unique relative minor ‘key’ for each corresponding red letter on the outside of the circle.

Why stop there?  Why not turn the 2nd note of the Major Scale into the new tonal center?  Or the 3rd note for that matter? This concept can be applied to all seven notes of a given Major Scale and each tonal center creates a different ‘mood’ and sound.  This is the concept of modes.

MODES – Modes are often overcomplicated and shrouded in mystery and confusion.  Many players are told that modes are “the secret weapons for any lead guitarist”.  While there’s definitely truth to that statement, modes are basically just scales.  There’s tons of scales out there, and modes are no different.  What makes them noteworthy is their relationship and connection to the ‘parent scale’ otherwise known as the good old Major Scale.

A cliche statement that you’ll often hear is that the Major Scale is “the mother of all scales”.  This doesn’t mean that it’s the coolest sounding scale, or that you NEED to use it in order to be a great guitarist.  It just means that, when you look at how the most common scales in modern music are connected back to the Major Scale, it seems to play the role of a ‘parental’ figure.  Some of the most popular scales used in music can be directly linked back to the Major Scale.

I’ll borrow an analogy I used in my previous blog on theory to explain the ‘subordinate’ role that modes play in relation to the Major Scale.  I compared the constant nature of an interval formula for a particular scale to that of a sports team; Traveling from city to city, where the stadium (the tonal center) can change but the distance of the field from end zone to end zone (the interval formula) will remain the same.

When talking about modes, you can slightly alter this analogy to say a certain team is on a ‘6 game road trip’ to different cities.  Each city’s stadium (each mode) has a different character, different weather (major, minor, or diminished) which contributes to how the game is played in that stadium.  But we all know where the home team is from if we get lost (the Major Scale).

So, to reiterate, when we turn each individual note of the Major Scale into the tonal center we get seven unique sounding scales or modes (including the Major Scale).  The names for these modes have ancient Greek origins and are as follows:

Ionian Mode       (same as the Major Scale)

Dorian Mode      (when the 2nd note becomes the tonal center)

Phrygian Mode   (when the 3rd note becomes the tonal center)

Lydian Mode      (when the 4th note becomes the tonal center)

Mixolydian Mode (when the 5th note becomes the tonal center)

Aeolian Mode     (when the 6th note becomes the tonal center, same as the Minor Scale)

Locrian Mode     (when the 7th note becomes the tonal center)


Each mode has its own ‘sound’ and character, but they can all (except for Locrian) be put into two basic categories; Major or Minor

Let’s look at the intervalic formula for each mode to see why (Remember that the tonal center is always the ‘1’ note in the interval formula.  This is why, for example, the Dorian mode doesn’t start with a ‘2’, even though it is the 2nd note of the ‘parent’ Major Scale) :

Ionian      = 1, 2, 3, 4, 5, 6, 7          (Major)

Dorian       = 1, 2, b3, 4, 5, 6, b7      (Minor)

Phrygian   = 1, b2, b3, 4, 5, b6, b7  (Minor) 

Lydian      = 1, 2, 3, #4, 5, 6, 7       (Major)

Mixolydian = 1, 2, 3, 4, 5, 6, b7        (Major)

Aeolian     = 1, 2, b3, 4, 5, b6, b7    (Minor)

Locrian     = 1, b2, b3, 4, b5, b6, b7 (Diminished)


In the introduction to theory, I discuss how the ‘flat 3rd’ is indicative of a minor sounding scale or chord.  Based on this logic, we can see that three of the modes are more minor sounding, three modes are major sounding, and the Locrian mode is diminished (because of the ‘flat 5th’ or ‘diminished 5th’).  You might also notice how the modal structure is identical to the Major Chord Scale (which I cover in the introduction) :


1st Triad   Major chord        (1,3,5)    =   Ionian Mode         

2nd Triad  Minor chord          (1,b3,5)   =  Dorian Mode

3rd Triad  Minor chord         (1,b3,5)   =  Phrygian Mode                                                            

4th Triad  Major chord         (1,3,5)    =  Lydian Mode             

5th Triad  Major chord        (1,3,5)     =  Mixolydian Mode         

6th Triad  Minor chord        (1,b3,5)    =  Aeolian Mode             

7th Triad  Diminished chord (1,b3,b5)   =  Locrian Mode


This further illustrates how nothing in music theory can function in isolation.  All concepts are connected.

MODAL USAGE AND APPLICATION – In all honesty, you can use these modes and their unique melodic content in any creative way that you’d like.  However, there is a logical way to use them in order to weave the tapestry of a piece through different musical landscapes.

For example, if I was writing a song in the key of ‘C’ Major but wanted to write a ‘dark’ sounding guitar solo, then my best option would be to shift the quality of the chord progression to a ‘minor’ sound.  Transitions between two different sections can sometimes be the most difficult part of composing a song.  Let’s say you have two catchy ideas, but one is ‘happier’ sounding while the other is ‘darker’ sounding.  How can you smoothly transition between these two sections?  Should you just treat the two ideas as separate songs to avoid mixing them together?  Well, you could do that, but if you felt strongly about marrying the two ideas then you could try transitioning from the Major key to its ‘relative minor’ or one of the other minor modes (Dorian or Phrygian).  Since none of the notes change (only the tonal center), this transition will sound very smooth, natural, and deliberate.

Another way would be to maintain the same tonal center (key of ‘C’ in this case) but to switch from ‘C’ Major to its ‘parallel minor‘.  The parallel minor in this case is ‘C’ minor.  The main difference between relative vs. parallel is that any ‘relative’ change will adhere to the  modal structure (the same family of notes as the parent scale).  While a ‘parallel’ shift alters the notes and sound of the parent scale itself.  This transition will sound a little more abrupt, but can be an effective way to deceive the listeners’ expectations.

One more option you have when changing the key of the parent scale is to follow the Circle of 5ths (or 4ths).  Changing the key in this way is known as modulation (although this term is sometimes used when any change of the tonal center occurs).  If you’re in the key of ‘C’ then a transition to either the key of ‘F’ or ‘G’ can yield pleasing results in regards to the transition.  The main reason for this is because there’s only one note of a difference between ‘C’ Major and ‘F’ or ‘G’ Major.  Even better, this one note is a mere half-step distance (distance of 1 fret) from either key (In ‘C’ Major, the ‘F’ note transitions to F# when modulated to ‘G’ Major.  And the ‘B’ note transitions down to Bb when ‘C’ Major is modulated to ‘F’ Major)

And, of course, you can always change the tonal center at random without any rhyme or reason.  When it comes to writing your own music, you don’t have to follow the rules.  Check out my blog on Music Theory’s Role in Songwriting to explore this topic further.

Well I think it’s time that we rap up this section on the Circle of 5ths and Modes.  Both topics have the potential to be dissected and discussed ad nauseam.  However, there’s enough information here which can enable you to become reasonably proficient in both areas.


SUS, DOMINANT, and 7th CHORDS – In my previous post on theory, I explain the concept of triads and how they are the foundation for all chords.  I also discuss how there are four basic types of triads; Major, minor, augmented, and diminished.  However, there are a few more chord ‘qualities’ which should be addressed.

SUS CHORDS – All triads are comprised of the 1st, 3rd, and 5th notes of a given scale.  And we also know that the 3rd note helps define the sound or ‘quality’ of the triad (whether it’s Major or minor).  So what would happen if we omitted or ‘suspended’ (Sus = suspended) the 3rd note and replaced it with something else?  Well there are only two other options in-between the 1st and 5th notes; the 2nd or the 4th.

A chord which suspends the 3rd and replaces it with the 2nd note in the scale is called a Sus2 chord, while a Sus4 chord utilizes the 4th note.  Sus chords have a more ‘open’ sound which can be harder to categorize in terms of their mood and quality.  Another important point to keep in mind is that the 2nd and 4th notes have to be natural to the Major scale if you’re going to use them for a Sus chord.  If you’re playing over a Phrygian modal sound, then a Sus2 chord won’t be applicable (but a Sus4 will work).

It is important to note that, in the Jazz world, Sus chords do not always omit the 3rd note completely.  Instead, jazz musicians will sometimes play the 3rd note an octave higher so that there’s reasonable separation between the 2nd/4th and the 3rd.

7th CHORDS – Depending on how comfortable you are with the intervalic system, you might already have an idea of what 7th chords are all about.  If we took each triad found within the Major Chord Scale and added the 7th note, then we have a formula and roadmap for using 7th chords in a given progression:


Ionian     – 1, 2, 3, 4, 5, 6, 7        = Major 7th Chord (1,3,5,7)

Dorian      – 1, 2, b3, 4, 5, 6, b7    = Minor 7th Chord (1,b3,5,b7)

Phrygian  – 1, b2, b3, 4, 5, b6, b7 = Minor 7th Chord (1,b3,5,b7)

Lydian     – 1, 2, 3, #4, 5, 6, 7      = Major 7th Chord (1,3,5,7)

Mixolydian- 1, 2, 3, 4, 5, 6, b7      = Dom 7th Chord (1,3,5,b7)

Aeolian    – 1, 2, b3, 4, 5, b6, b7   = Minor 7th Chord (1,b3,5,b7)

Locrian    – 1, b2, b3, 4, b5, b6, b7=Minor 7 b5 Chord (1,b3,b5,b7)

So if you wrote a strictly ‘diatonic’ chord progression in a Major key, then you could add the corresponding 7th note to any of the triad-based chords in an effort to spice things up a bit.  That being said, you should still always use your ears to make sure the 7th chord is what you want in your song.  7th chords might not be appropriate for every musical context as they tend to have a ‘jazzy’ sound.

DOMINANT CHORDS – Now, there is a new term in the list of 7th chords above which needs to be explained.  The fifth chord down from the top is labeled “Dom 7th Chord”.  This is short for Dominant 7th Chord.  Dominant chords are interesting because they share both major and minor qualities.  A dominant chord will always be built upon a major triad (1,3,5) with an added ‘flat 7th’ on top.  This gives it a kind of ‘bluesy’ sound.

CONCLUSION – I hope you’ve learned a lot from this article and feel free to share it with others and use it as a ‘music theory cheat sheet’ of sorts.  Admittedly, there is much more that can be explored in the world of music theory that I have not touched upon.  But this has been my attempt at presenting you with the ‘essentials’ in a practical and straightforward way. If you have questions about any of the material or you simply want to dig deeper into music theory, please contact me and I’d be glad to help you out!








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