Diminished Chords.
What are they? When and where can you use them?
When you are studying basic music theory on your guitar, you will eventually come across something called the “diminished” or “diminished 7th”, or maybe even the “half-diminished” chord. What are they? Why do they exist? Why do we need them in music? How often are they used?
If you search Google, you may find the following explanation: “Diminished chords inject a sense of drama, tension, and suspense into music. They also have a distinct timbre that sounds dark, dissonant, and eerie. Their oddness makes them unique! However, the flattened fifth makes diminished chords sound unstable and creates a desire for tonal resolution.”
Clear as mud? Let’s look into it.
Diminished chords are “transitionary” - - transitional?
These types of chords are not chords you would normally ever use to start or stop a song. They sound out of place when they are not in the context of a chord progression. A diminished chord needs to be in a progression as a “pivotal” or “resolving point” in a song.
Certain types of diminished chords have existed in jazz music since the beginning. They sometimes show up in pop songs, but they are rarely used in modern music. You probably won’t hear diminished chords in rock or country music, but you might hear them in blues music. Eric Clapton uses them often in some of his songs.
So, what makes up a diminished chord?
The structures of diminished chords are based on a “minor chord”, but with a “flatted” or “diminished” 5th in the chord structure. Notice I said, “chords”, plural. Yes, there are three types of diminished chords.
The basic diminished triad chord structure has the root, the minor 3rd and a flatted 5th.
For example, if we build a “C” diminished triad, we will need the “C” as the root or the “I”. Next, we will need the minor 3rd, which is the “Eb”. The diminished 5th of C is “Gb” (not F#). It must be “Gb” because “G” is the perfect 5th - and all we are doing is lowering that perfect 5th one half step down to Gb.
The diminished chord is a sort of perfect structure by design mathematically. If you notice, the interval between the “C” and the “Eb” is 3 half steps or a “minor 3rd”. Now, look at the interval between “Eb” and “Gb”. It is also 3 half steps or a “minor 3rd”.
The Half-Diminished chord.
This chord is often used in traditional jazz music. The “half-diminished” chord is sometimes named the “minor 7 flat 5” (m7b5) chord. It is one of those chords that has even more depth and emphasis as a pivotal point in a chord progression. The only note that gets changed (or added) is the “Bb” on the 3rd string 3rd fret.
* The half-diminished symbol looks a little this: “Ø” - Basically, a circle with a line through it. Sometimes they are written smaller: “ø”.
As you can see, the half-diminished structure is the same as the diminished structure, except for the “Bb” that gets added as the dominant 7th. This why you can also look at this chord as a minor 7th chord with an added diminished or “flatted” 5th.
The Diminished 7th chord.
The only change we make from half-diminished to diminished 7th is - we move the “Bb” one half step lower to the “double-flatted 7th” position “Bbb”. Well, what is a double-flatted 7th? The reasoning behind this is that we do not refer to this note as the major 6th (A), because we are dealing with the altering of the dominant 7th note by moving it one half step below the dominant 7th position in the chord structure, thus calling it a “double-flatted 7th”.
Oh! Look at this! We quite literally have four minor intervals place next to each other in this structure.
C to Eb is a minor 3rd, Eb to Gb is a minor 3rd, Gb to Bbb is a minor 3rd, and Bbb back to C is a minor 3rd - as you can see in this chart:
The diminished 7 chord is used frequently in traditional jazz and blues music as a sort of passing chord between the “IV” and the “I” in the chord progression.
You can experiment with all three diminished chords by playing and listening to what they sound like in the following chord progressions.
The first diminished chord you see is the “Cm7b5”. Remember, this is also considered a “Cø” (C half-diminished) chord. The fourth chord in this progression is the “D°”. The And finally, the eight chord in this progression is the “Db°7”.
I hope this helps you better understand the mysteries of the diminished, half-diminished and diminished 7th chords.
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Dave