"Seventh Chords"
7 Kinds of Sevenths
That Add
Character to Songs
 Seventh
Chords are used to to create hip sounds with the music. The four
chords discussed at Music Theory Chords
can all have a 7th interval added to create a new sound.
There are 7 kinds of sevenths when you can create
by adding major and minor 3rds.
Why
only seven and not eight? It seems like Karma to have seven kinds of
sevens. Below we
will explore why there are seven you need to learn and use.
Types of Seventh Chords
Going
back to the original chords we have the option of adding the scale
interval of minor 7
and major 7 to the chords. However, For the augmented chord only a
major 7 can be added, that is because a minor 3rd added to the chord is
the major 7. We'll look at this closer below.
Major Chord Sevenths
There are two major chord sevenths each called a
specific name. The dominant seventh (C7 for C dominant 7) and the major
seventh (CM7 for C major 7). Notice how the notes will still be on
either all lines or all spaces on the staff.
 The
Major Chord Dominant
Seventh is the addition of the minor 3rd to the
chord, that is a minor 7th (b7). Here is how this chord is
mathematically.
Major
Chord Dominant
7th ; C7
Intervals: 1 3
5 b7
Half Steps: S + 4 + 3 + 3
Notes
for C7: C
E G Bb
The
Major Chord Major
Seventh chords uses 4 half steps to add the major seventh
(M7).
Major
Chord Major
7th ; CM7
Intervals:
1
3
5 7
Half
Steps: S + 4 +
3 + 4
Notes
for CM7: C
E G B
Minor Chord Sevenths
Again there are two minor chord sevenths each
called a
specific name. The dominant seventh (Cm7 or C-7 for C minor dominant 7)
and the major
seventh (CmM7 or C-M7 for the C minor major 7). Notice how the notes
will still be on
either all lines or all spaces on the staff the modification to the
note makes the difference let's take a close look.
 The
Minor Chord Dominant
Seventh is the addition of the minor 3rd (b3 or
m3) to the
chord, that is a minor 7th (b7). With the third being minor as well.
Here is how this chord is
mathematically.
Minor
Chord
Dominant
7th ; C-7
Intervals: 1
b3 5 b7
Half Steps: S + 3 + 4 + 3
Notes
for C7: C Eb G
Bb
The
Minor Chord Major
Seventh chords uses 4 half steps to add the major seventh
(M7).
Minor
Chord Major
7th ; C-M7
Intervals:
1
b3 5 7
Half
Steps: S + 3 + 4 + 4
Notes
for C7: C Eb G
Bb
Diminished Chord Sevenths
Again there are two minor chord sevenths each
called a
specific name. The dominant seventh (Cm7 or C-7 for C minor dominant 7)
and the major
seventh (CmM7 or C-M7 for the C minor major 7). Notice how the notes
will still be on
either all lines or all spaces on the staff the modification to the
note makes the difference let's take a close look.
 The
Diminished Chord
Dominant
Seventh is the addition of the minor 3rd (b3 or
m3) to the
chord, that is a diminished minor 7th (bb7). This is unusual as all the
notes are minor 3rds. Called the diminished 7th.
Diminished
Chord 7th ; C°7
Intervals: 1
b3 b5 bb7
Half Steps: S + 3 + 3 + 3
Notes
for C7: C
Eb Gb Bbb
The Half Diminished
Chord Seventh chords uses 4 half steps the major
3rd to add the seventh (b7).
Diminished
Chord Half
7th ; Cø7 or Cm7b5
Intervals:
1
b3 b5 b7
Half
Steps: S + 3 + 3 + 4
Notes
for C7: C Eb Gb
Bb
Augmented Chord Seventh
There is only one chord seventh for the
augmented chord. It is the addition of a 3rd that makes it
a major
seventh addition.
 The Augmented
Chord Seventh is the addition of the
minor 3rd to the
chord, that creates a Major 7th (M7) interval addition. Here
is how this chord is
mathematically.
Augmented
Chord 7th ; C+7
Intervals: 1 3
5 7
Half Steps: S + 4 + 4 + 3
Notes
for C7: C
E G+ B
There is No minor 7th interval
for the augmented
chord. Trying to add the m7 to the chord
would make this addition an addition of 2 half steps which is a second
addition and violates the interval 3rd addition to be a chord
construction.
Also this chord acts differently and is not
considered a seventh chord. It would take to long to explain it here,
so stick to the 7 kinds of sevenths and you will be safe in 95 percent
of your chord identifications.
Seventh Chord Summary
You've just had a quick introduction to basics of
seventh chords. The staff line below covers the seven kinds of
sevenths to show the relationships for the C chord types.
Be aware
that the symbols for the chords vary by instruction or instructor. Most
musicians can adapt to the different writings. Sometimes it just takes
a little getting use to it. Variations also include superscript and
subscripts.
In jazz the half diminished 7 chord is often
referred to as the minor 7th with a flat 5. I think that this may be
due
to the fact that the half diminished chord was not taught with the name
associated with it.
Play the chords in sequence and listen to the
character changes associated with each.
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