Here’s How To Form Dominant Seventh Chords Using Diminished Triads

In our FREE 16 week chord revival program, we covered the diminished triad and other chord classes.

Now that we’ve covered the definition, intervallic components, and formation of the diminished triad, I’ll be showing you one of the applications of the diminished triad in the chord formation of the dominant seventh chord.

Let’s quickly review the diminished triad.

Review of Diminished Triads

The diminished triad is the triad of the seventh degree of the major scale.

Using any known major scale, C major scale for example:

We can form the diminished triad on the seventh degree using the pick and skip technique. The seventh tone is B:

…if we pick B and skip C, pick D:

…and skip E, then pick F:

…this would produce the B diminished triad.

Intervallic Breakdown of the Diminished Triad

No matter how simple or complex a chord is, it can be broken down into intervals. The intervals derived from breaking down a chord are known as ‘intervallic components.’

The intervallic components of the B diminished triad are…

B-D:

…a minor third interval.

B-F:

…a diminished fifth interval.

Put together, the intervallic components of the diminished triad are:

Minor third
Diminished fifth

The diminished fifth interval is the key interval in this chord. The diminished triad is called a diminished triad because of this interval.

Suggested reading: Diminished Triads + Chord Cheat Sheet.

Here are diminished triads in all twelve keys:

C diminished triad:

C# diminished triad:

…which can also be spelled as Db diminished triad.

D diminished triad:

D# diminished triad:

…which can also be spelled as Eb diminished triad.

E diminished triad:

F diminished triad:

F# diminished triad:

…which can also be spelled as Gb diminished triad.

G diminished triad:

G# diminished triad:

…which can also be spelled as Ab diminished triad.

A diminished triad:

A# diminished triad:

…which can also be spelled as Bb diminished triad.

B diminished triad:

Relationship Between Diminished Triads and Dominant Seventh Chords

Let’s look at the roles of the diminished triad and the dominant seventh chord in harmony.

The Diminished Triad in Harmony

The diminished triad is the triad of the seventh degree of the major scale, which is technically known as the leading tone.

There are three classes of chords in the major scale – the major, minor, and diminished triads.

In traditional harmony, the diminished triad is not used because it sounds unpleasant and has the tendency to resolve to a major or minor triad.

Owing to the instability of the diminished triad, it is not regularly used in harmony. However, the diminished triad (aka – “leading tone triad”) has a strong pull towards the tonic chord in the key.

The Dominant Seventh Chord in Harmony

The term dominant is the technical name of the fifth tone of the major scale. The fifth tone in the major scale of C is G.

Using the C major scale to form a seventh chord on G would produce the G dominant seventh chord. Check it out below:

The G dominant seventh chord above is arguably the chord with the strongest pull to the C major triad, which is the tonic chord of the key. This makes the dominant seventh chord one of the commonly most used chords in harmony.

“Here’s the relationship between the diminished triad and the dominant seventh chord…”

Both the dominant seventh chord and the diminished triad all have a strong sense of attraction towards the tonic (the “1,” the “root,” the home base.)

But most importantly, the leading tone triad is the upper part of the dominant seventh chord.

In the key of C, the leading tone triad (B diminished):

…is the upper part of the dominant seventh chord (G dominant seventh chord):

Therefore, isolating the diminished triad from the dominant seventh chord would produce:

…the “part over root” voicing of the dominant seventh chord.

Suggested reading: “Part Over Root” Voicings.

I’ll be showing you how to form the dominant seventh chord using these diminished triads in the next segment. With this, you can start using the diminished triad more often.

Before we do so, take time to study the part over root voicing technique.

Formation of the Dominant Seventh Chord Using The Diminished Triad

Considering that the B diminished triad:

…is the upper part of the G dominant seventh chord:

We can form the G dominant seventh chord by playing the B diminished triad:

…over G in the bass:

Let’s create a formula for this chord formation process…

The interval between B diminished (the part) and G (the root) is a major third.

Therefore, if we form the diminished triad a major third above any given root, this would produce the dominant seventh chord.

For example, considering that the third tone of the C major scale is E, playing E diminished over C on the bass would produce the C dominant seventh chord. Check out the formula below:

Over any given root, forming a diminished triad on its third tone would produce a dominant seventh chord.

Using this formula, we can form the diminished triad on the third tone of the major scale of all the notes on the piano. Check out the dominant seventh chords below:

C dominant seventh chord:

E is the third tone in the major scale of C. Therefore, E diminished triad played over C in the bass (aka – “Edim/C”) would produce the C dominant seventh chord.

Db dominant seventh chord:

F is the third tone in the Db major scale. Playing F diminished triad played over Db in the bass (aka – “Fdim/Db”) would produce the Db dominant seventh chord.

D dominant seventh chord:

F# is the third tone in the D major scale. Playing F# diminished triad played over D in the bass (aka – “F#dim/D”) would produce the D dominant seventh chord.

Eb dominant seventh chord:

The third tone in the major scale of Eb is G. Therefore, G diminished triad played over Eb in the bass (aka – “Gdim/Eb”) would produce the Eb dominant seventh chord.

E dominant seventh chord:

The third tone in the major scale of E is G#. G# diminished triad played over E in the bass (aka – “G#dim/E”) would produce the E dominant seventh chord.

F dominant seventh chord:

A is the third tone in the F major scale. If A diminished triad is played over F in the bass (aka – “Adim/F”), this would produce the F dominant seventh chord.

F# dominant seventh chord:

A# is the third tone in the F major scale. Therefore, A# diminished triad played over F# in the bass (aka – “A#dim/F#”) would produce the F# dominant seventh chord.

G dominant seventh chord:

B is the third tone in the major scale of G. Therefore, B diminished triad played over G in the bass (aka – “Bdim/G”) would produce the G dominant seventh chord.

Ab dominant seventh chord:

C is the third tone in the Ab major scale. Playing C diminished triad over Ab in the bass (aka – “Cdim/Ab”) would produce the Ab dominant seventh chord.

A dominant seventh chord:

C# is the third tone in the A major scale. Playing C# diminished triad over A in the bass (aka – “C#dim/A”) would produce the A dominant seventh chord.

Bb dominant seventh chord:

The third tone in the major scale of Bb is D. Therefore, D diminished triad played over Bb in the bass (aka – “Ddim/Bb”) would produce the Bb dominant seventh chord.

B dominant seventh chord:

The third tone in the major scale of B is D#. D# diminished triad played over B in the bass (aka – “D#dim/B”) would produce the B dominant seventh chord.

Final Words

Now you see how easy it is to feature the diminished triad in the formation of the dominant seventh chord.

Feel free to use the diminished triad on the right hand while voicing the dominant seventh chord using the “part over root” voicing technique.

Heck, you can even upgrade the diminished triad part to a diminished seventh chord. For example, instead of Edim/C:

…to produce C dominant seventh chord, we can go ahead and play E diminished seventh chord:

…over C in the bass. This would produce:

…the dom7 [b9] chord, a common altered dominant chord.

We’ll talk a lot more about this in subsequent posts.

All the best!

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Chuku Onyemachi

Head of Education at HearandPlay Music Group

Onyemachi "Onye" Chuku is a Nigerian musicologist, pianist, and author. Inspired by his role model (Jermaine Griggs) who has become his mentor, what he started off as teaching musicians in his Aba-Nigeria neighborhood in April 2005 eventually morphed into an international career that has helped hundreds of thousands of musicians all around the world. Onye lives in Dubai and is currently the Head of Education at HearandPlay Music Group and the music consultant of the Gospel Music Training Center, all in California, USA.

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Tagged as: diminished and dominant 7ths, dominant 7, dominant 7 chords