Music Theory
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Music Theory: Diminished/Augmented Triads and Seventh Chords

We last left off with major and minor triads, where the third was the deciding factor for the final chord. In both cases the root and the fifth remain the same. When we raise or lower the fifth, we get into augmented and diminished triads. Recall a major chord Is a stacked third, first a major third and then a minor. And a minor chord was the exact opposite, a minor third and then on top of that a major third. What happens when we stack two minor thirds on top of each other? We will get a diminished triad. In this lesson, we will talk about Diminished/ Augmented Triads and Seventh Chords

Diminished and Augmented Triads 

A C major chord is C-E-G, if instead we make a Cdim chord two minor thirds apart, that would be the notes C-Eb-Gb. The formula for the diminished chord is 1-b3-b5. As you can see the third and fifth are both flattened, play the chord and get an idea of how it sounds. It has a dissonant sound and immediately feels like it needs to stabilize to a more consonant chord. By using he diminished triad in our music we add a tension that needs to be resolved.  

Diminished Chord (Key of C)
Diminished Chord (Key of C)

Some examples of diminished triads are “Michelle” by The Beatles. The line where he sings “go together well” is a diminished chord followed by a major chord. It is also in “Somewhere Over the Rainbow” during the “chimney tops” lyric.

Often when you look up chords online, they may be lacking in necessary diminished chords as the player assumes you are singing the diminished part. Remember when singing along with an instrument or a band different parts of the chord can be broken up among vocals or instruments. 

Diminished triads are not as common as other diminished chords, like those with four notes instead of three. In the next section we will talk about some more advanced diminished chords, but first we need to learn our augmented triads! 

Before we stacked two minor thirds on top of one another, so now we will stack two major chords together. This gives us the formula 1-3-#5, so a C augmented is C-E-G#. By raising the fifth, or augmenting it, we also give this chord a tension that needs resolved. This chord has a tendency to feel like it is building to something. You can label the augmented chord as Caug or C+ both mean the same.  

Augmented Chord (Key of C)
Augmented Chord (Key of C)

After playing this chord you should sort of recognize some specific tunes that use it, it is a very distinct triad. Bowie uses it in “Life On Mars” during the line ‘spit in the eyes of fools.’ At the beginning of The Beatles “Oh Darling,” they play Eaug to A major. Now without looking these chords up try playing both all on your own, apply each formula to the key of E and then A.

We sonically build the song up in the first two words by using that augmented chord. Usually augmented chords are played very briefly before resolving. A great song example that uses both aug and dim chords is Randy Newman’s “You’ve Got a Friend in Me.” Both augmented and diminished chords are used sparingly in places where a songwriter is looking to build or breakdown emotion. In the right musical spot their dissonance can really make a song great. 

Now we have come to the end of the triads, remember these only consist of major, minor, diminished, and augmented. Despite these chords all being simple distances of major and minor thirds, they are the basic music structures of all songs. Most popular tunes out their consist of chord progressions of major and minor chords with augmented or diminished peppered in.

You can make an entire career out of music with just triads. However, we will now add a fourth note to our chords using the same principles as the triads. As long as you have been following along on a keyboard or other chord instrument you will find that adding more notes is actually a very simple process! 

Seventh Chords 

A seventh chord is simply a seventh note added to a triad. Now there are a variety of seventh chords, and they all depend on which triad you start with and whether or not you flatten or raise the seventh. Don’t overthink or complicate the process, just follow the rules of your chord building. In the C major scale; 

C Major Scale

The seventh note is B, and with the distance of G-B we are just stacking another third onto our chord. As with triads depending on the major or minor third and the order they are stacked in, this will tell us what seventh chord we are dealing with.  

Major Seventh 

Major Seventh Chord
Major Seventh Chord

If we build a chord with consecutive thirds being major, minor, and major we will get a major seventh chord. Recall a C major triad is C-E-G so add another major third above that and you get C-E-G-B or 1-3-5-7. This can be written as Cmaj7 or CM7. A great example of this chord is Chicago’s “Colour My World” and “The Girl from Ipanema.”  

Minor Seventh 

Minor Seventh Chord
Minor Seventh Chord

Now it makes sense that these chords will be built from a minor triad with the formula of stacked thirds being minor, major, and minor. C minor is C-Eb-G and add the minor third we get C-Eb-G-Bb or 1-b3-5-b7.

It can be notated as Cmin7 or Cm7 and has a very jazzy quality to it! It just as well can be used in funk as it is the chord of the chorus in “Funkytown.” We also hear it in “Killing Me Softly,” it is a chord that diversifies through rock, pop, soul, funk, and jazz. 

Dominant Seventh 

Dominant Seventh Chord
Dominant Seventh Chord

If we now order our thirds in major, minor, and minor we get a dominant seventh. Its formula is 1-3-5-b7 making a C7 chord C-E-G-Bb. There is a tritone interval between the third and seventh which gives it dissonance. That dissonance is what really makes rock n roll what it is. The dominant seventh is heavily used in blues and rock giving them their specific sound.

Later you will learn the most common chord progression is known as the 1-4-5, those being major chords. By adding some sevenths the tune gets a lot more rockin! Chuck berry added sevenths on all the 1-4-5 for his song “Rock and Roll Music.” There is a famous Beatles story by Paul McCartney where he tells how they took a bus across town to learn B7 on the guitar. They had no chord books back then and that dominant seventh was essential to the sound they emulated.  

Diminished Seventh 

Diminished Seventh Chord
Diminished Seventh Chord

The diminished seventh is three minor thirds apart, giving us 1-b3-b5-bb7 (that bb means we flatten the note twice) which gives us C-Eb-Gb-A or Cdim7. During the song “When You Wish Upon a Star,” at the lyrics of ‘anything your heart’ it moves from a minor seventh to a diminished seventh. Another use of a diminished seventh is in the Maroon 5 song “This Love” the chord before the chorus starts. 

Because the diminished seventh is three minor thirds it is a symmetrical chord, and since we have only 12 notes that means there can only be three unique diminished sevenths! G#dim7, Bdim7, Ddim7, and Fdim7 all have the same notes. As well as the four Cdim7, Adim7, D#dim7, and F#dim7. And the final four diminished seventh chords that share all the same notes are Bbdim7, Edim7, Gdim7, and C#dim7. 

Half-Diminished Seventh 

Half-Diminished Seventh Chord
Half-Diminished Seventh Chord

The stacked thirds in a half-diminished seventh chord are minor, minor, and major. The formula is 1-b3-b5-b7 which would make Cm7b5 the notes C-Eb-Gb-Bb. This chord can also be called a half-diminished chord or a minor seventh flat five, which is the best name that describes it.

Play this chord and it sounds very different than a diminished despite the similar names. If you play The Beatles song “Because” the second chord is a half-diminished seventh. It is also in the song “Skylark” by Hoagy Carmichael. In fact, this chord is very common in popular American jazz standards. 

Minor Major Seventh 

Minor Major Seventh Chord
Minor Major Seventh Chord

This seventh chord is stacked as a minor, major, and major. The formula 1-b3-5-7 making CmM7 the notes C-Eb-G-B. A great example of this minor major seventh chord is in the song “Us and Them” right after the lyrics ‘us and them.’

This chord is also heard in “It’s My Party” by Leslie Gore. It is also sometimes referred to as the Hitchcock Chord because it was prominently used in the score for Psycho. While it is clearly used in more than just eerie situations, it certainly is at home with a horror soundtrack. 

Augmented Major Seventh 

Augmented Major Seventh Chord
Augmented Major Seventh Chord

For this chord the stacked thirds are major, major, and minor giving us 1-3-#5-7. So for Cmaj7#5 the notes would be C-E-G#-B. This is a chord we don’t see as often but is used in jazz or again in any scary or tense soundtrack where we require dissonance. 

So far, we have been constructing seventh chords on top of major and minor triads, but we can also create sevenths by adding them to augmented and diminished chords! 

Augmented Seventh 

Augmented Seventh Chord
Augmented Seventh Chord

The formula for the augmented seventh is 1-3-#5-b7, which means it is simply an augmented triad with a minor seventh. This chord in the key of C will be Caug7 or C+7 and is made up of the notes C-E-G#-Bb. This chord has a very dissonant quality and clearly needs resolved.

Most often when you hear the augmented seventh it will conclude on a perfect fifth below. So if we have Caug7 it would resolve to a F major chord (C is a perfect fifth away from F). Try playing those chords in that order and see how nice it concludes with that progression.  

Diminished Major Seventh 

Diminished Major Seventh Chord
Diminished Major Seventh Chord

Before we had a minor seventh added into an augmented triad, here we get a diminished triad but with a major seventh. So the formula is 1-b3-b5-7 making CmM7b5 C-Eb-Gb-B. It has a tritone so it will again be used in jazz or any situation needing a tense and odd tritone! 

Dominant Seventh Flat Five 

Dominant Seventh Flat Five Chord
Dominant Seventh Flat Five Chord

This chord is built with the formula 1-3-b5-b7, giving C7b5 the notes C-E-Gb-Bb. This is not something you will see too often, but the better you get at naming these chords and recognizing them, the more you will hear examples. 

There are an awful lot of chords above to memorize and it may seem daunting. We are clearly getting into chords that are not as commonly used and can seem a little complicated. As if to make matters worse some of these chords can have different names and can be known as altered chords. This is where you change a normal chord note with some other note from the scale.

This happens when you see slash chords, they have an altered bass note other than the normal root. So yeah, this can all really get heavy fast (that line is to be read in the voice of Neal from The Young Ones). However, it isn’t necessary to grasp all these right at the moment.

Even after years of reading and studying music theory we still have to look up certain chords, it’s easy to forget all the rules even for those trained. The key is to make sure you understand the basics. Yeah sure you might not remember the major, minor, major formula initially, but you are aware of what this means.  


Practice your Chords!

Most of the time you can just take the scale and chord and figure out each note with a little practice. You can look at sheet music, find two notes and know the name and sound of that interval.

You can see some of the most common three and four note chords and have a solid idea of how they are built. All of this knowledge is worth studying and practicing as it makes a student a better musician. Yes you can make a living playing three major chord songs in a few different keys. And there is nothing wrong with three chord rock and pop, some of it is great.

However, once we get into more complicated chords, we get jazz standards, metal, funk, we can expand our musical horizons. It also makes it easier to play with others and when composing your own material.

One of the best ways to solidify the study of music theory is to teach it! As you learn chords, show them to others that don’t know. Once you can explain a new chord to a beginner the more confidence you will gain in chord theory! 

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  1. As a newbie in music, I find these blogs very helpful in getting me back into the groove of learning new things!

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