If you’ve read our post on all the types of chords there are in music, you’ll already know that there are lots of different kinds. One of those types that is very common in jazz music is the seventh chord.
In this post, we’re going to look at what they are and everything you need to know about them, but first let’s cover what exactly is a seventh chord.
What Is A Seventh Chord?
A seventh chord is a type of chord that is built by taking a triad chord and adding an additional note: the 7th note of the scale.
For example, if we took a C major triad and added the seventh note of C major scale (B) we would then be playing a C major 7 chord.
The 5 Types Of Seventh Chords
In music, there are five different types of 7th chords.
Each of these types uses different intervals between the notes in the chord which gives it a different sound and feel.
The five types are:
- Major 7th
- Dominant 7th
- Minor 7th
- Half diminished 7th
- Diminished 7th
Now we’ll take a look at each type in a bit more detail and how to build them.
Major 7th chords
First we’ll take a look at a major 7th chord.
Major 7th chords are built by taking the major triad and adding a 4th note which is a major 7th interval about the root note.
A C major 7th chord would use the notes C, E, G and B.
There are a few ways to write a major 7th chord as a chord symbol.
You might see it written as whatever note is the tonic of the chord + M7, Ma7, Maj7, or Δ.
When writing M7 it’s important that the M is an uppercase M as a lower case m would indicate a minor 7th chord.
Dominant 7th chords
Up next we have a dominant 7th chord.
A dominant 7th chord comes from the mixolydian mode which is also known as the dominant scale as it’s built on the 5th degree of the scale (called the dominant).
A dominant 7th chord is built by taking the major triad and adding a 4th note which is a minor 7th interval about the root note.
In C, this would be C, E, G and Bb.
A dominant 7th chord symbol or the way of writing it in shorthand is to just have the tonic note of the chord followed by a 7.
So if you saw a C7 chord symbol, it’s telling you to play a C dominant 7th chord.
Minor 7th Chords
Another type of 7th chord that is very common is a minor 7th chord.
Instead of using a major triad, these are built using a minor triad with a minor 7th interval.
In C this would be C, Eb, G and Bb.
Minor 7th chords tends to be written using a lowercase m with a number 7 or by writing min7 after the tonic note as shown below.
Again, it’s important to write minor 7th chords with a lowercase M otherwise you’ll be indicating a major 7th chord.
Half diminished 7th chords
Next, we have half diminished 7th chords.
Half diminished chords come from the locrian mode which is the 7th mode of the major scale.
These are built by combining a diminished triad chord with a minor 7th interval which in C would be C, Eb, Gb and Bb.
Half diminished 7th chords are typically notated as a small circle with a line through it followed by a 7 like this: ø7. You could also see it written as 7 b5 which means the same thing.
Diminished 7th chords
And last, but not least, we have a diminished 7th chord which are sometimes called fully diminished 7th chords.
Diminished 7th chords are built using a diminished triad with a diminished 7th interval with every interval between each of the notes being 3 semitones apart.
In C this would be C, Eb, Gb and Bbb.
To notate a fully diminished 7th chord you’ll often see it written as o7 or by writing dim7.
Summing Up Seventh Chords
I hope that helps to make a bit more sense of 7th chords and what you should play when you see their chord symbols on a chart.
They’re vitally important to know about especially with more modern music like pop and jazz where they’re used extensively.
If you have any questions just pop a comment below and I’ll try to answer!