How to construct seventh chords
A seventh chord is a 4-note chord. Like triads, they are formed by stacking up
thirds on top of a fundamental note. You can think of them in two ways, either in
terms of their intervals or by their scale alterations. Assuming you know how major,
minor, and diminished triads are formed, you can form the various types of
seventh chords by adding a note a seventh above the root to the triads:
| type
of triad |
type
of seventh |
resulting
seventh chord |
| major
|
M7 (major seventh)
|
maj7 (major seventh)
|
| major
|
m7 (minor seventh)
|
7 (dominant
seventh)
|
| minor
|
m7
|
m7 (minor
seventh)
|
| sus
|
m7
|
7sus (seven sus)
|
| diminished
|
m7
|
m7(b5) (minor
seventh, flat five--some people call it "half-diminished")
|
| diminished
|
d7
|
º7 (diminished
seventh)
|
| minor
|
M7
|
m (maj7)
|
As an exercise, you should write out the various types of seventh chords in
other keys. Start out with F and G major and work your way around the
circle.
The other way to think about chord formation is by starting with the
degrees of the major scale involved in making the major seventh chord, and then
making any necessary alterations. For example, in C major, the Cmaj7
chord is formed taking the 1st, 3rd, 5th, and 7th notes of the C major scale
(that is, C-E-G-B). The second chord in the series, C7 is
formed by taking the 1st, 3rd, 5th, and lowered 7th. Lowering and raising
are indicated by "-" and "+" signs and always result in a
change of one half step down or up from the maj7 scale degree.
If you play the chords in the following order from left to right you will
only change one note at a time--that scale degree is marked in red in the table
below. This makes a good keyboard exercise and should be transposed to
other keys systematically around the Circle of Fifths:
|
quality
|
major seventh
|
dominant seventh
|
seven, suspended 4th
|
minor seventh
|
minor seventh, lowered fifth
|
diminished seventh
|
|
example
chord
symbol
|
C maj 7
|
C7
|
C7sus
|
Cm7
|
Cm7(b5)
|
Co7
|
|
degrees
|
|
|
|
|
|
|
|
7
|
7
|
-7
|
-7
|
-7
|
-7
|
--7
|
|
5
|
5
|
5
|
5
|
5
|
-5
|
-5
|
|
3
|
3
|
3
|
4 (replaces 3)
|
-3
|
-3
|
-3
|
|
1
|
1
|
1
|
1
|
1
|
1
|
1
|
| |
|
|
|
|
|
|
|
example
(click to play)
|
|
|
|
|
|
|
We can make a chord scale out of seventh
chords the same way we have done with
triads.
The qualities of the seventh chords in any key are always the same:
| maj7 |
m7 |
7 |
m7(b5) |
| I,
IV |
ii,
iii, vi |
V |
vii |
Keyboard Exercise
Use the study worksheet to review the notes of the major
scale and how the chords are written on the staff. Be able to recognize and write
the notes on either the bass or treble clef.
If you play the chords in the following progression you will only move one
note a time, and it will always be a change of a half-step. Remember the formulas
for the scale degrees above and note which is the one degree that changes each time:
| C maj 7 |
C7 |
C7sus |
C7 |
Cm7 |
Cm7(b5) |
Co7 |
http://willshare.com/~willeyrk/music247/week3/seventh
©2001 Robert Willey