Seventh chords are the most important chords after the major and minor triads. They consist of the major or minor triad plus the
seventh scale degree, which may be modified depending on the type of seventh chord required.
Types of seventh (with formula)
The dominant seventh (1 3 5 b7)
This chord is generally referred to simply as a
seventh chord, e.g.,
C7. The name
dominant comes from the
dominant scale degree, i.e. the fifth degree (note) of major or minor scales. Originally ALL seventh chords were built on this scale degree. This is no longer the case as they now often appear built on any scale degree, but the name has stuck.
Example
G seventh (G7) =
1 3 5 b7 of the
G major scale (GABCDEF#) =
G B D F
Some common shapes are:
320001 = GBDGBF
353433 = GDFBDG
XX5767 = XXGDFB
The major seventh (1 3 5 7)
The word ‘
major’ in this case is referring to the fact that the seventh scale degree is not a
flat seven, as it is in the case of the
dominant seventh, but simply the unmodified seventh note of the
major scale
G major seventh (G maj7) = 1 3 5 7 of the
G major scale (GABCDEF#) =
G B D F#
Some common shapes are:
320002 = GBDGBF
XX5432 = XXGBDF#
The minor seventh (1 b3 5 b7)
For example,
Am7 = 1 b3 5 b7 of the
A major scale (ABC#DEF#G#) =
A C E G (notes 3 & 7 have been flatted from sharp notes to natural notes)
Some common shapes are
X02010 = AEGCE
X02213 = XAEACG
575555 = AEGCEA
The minor major seventh (1 b3 5 7)
This chord is very rare and also very discordant.
For example,
Amin maj7 = 1 b3 5 7 of the
A major scale (ABC#DEF#G#) =
A C E G#
Some typical shapes are:
X02110 = XAEG#CE
577595 = AEACG#A (the high
A is often muted in this shape to avoid a semitone clash with
G#)
The diminished seventh (1 b3 b5 bb7)
This is a very useful chord because it has some unusual properties. The
bb7 note (double flatted seventh) sounds the same as the 6th note of the scale, but to be correctly named as a
diminished seventh, the 7th degree of the major scale has to be
double flatted.
For example
E diminished 7th =
1 b3 b5 bb7 of the
E major scale (EF#G#ABC#D#) =
E G Bb Db
An unusual property of the diminished seventh chord is that the distance (
interval) between each note is equal. The interval is a
minor third. As all the intervals are identical, any one of them could be the root. Which means every diminished seventh shape can have four names
For example, a common diminished seventh shape such as
XX1212 could be
Eb (or D#)
dim7,
A dim7, C dim7 or
Gb (or F#)
dim7
This ambiguity of identity makes them ideal chords for changing into other keys.
Typical shapes (e.g., E dim7)
XX2323 = X X E Bb Db G
X7868X = X E Bb Db G X
The only other chord that exhibits this strange property is the augmented triad (1 3 #5) as it’s the only other chord with equal spacing between its notes. The interval separating them is a major third, rather than the minor third of the diminished seventh chord.
The half diminished seventh (1 b3 b5 b7)
This chord is less common than the
fully diminished seventh
For example
E half dim7 = 1 b3 b5 b7 of the
E major scale (EF#G#ABC#D#) =
E G Bb D.
Typical shapes are:
XX2333 = X X E Bb D G
X7878X = X X E Bb D G
Another name for this chord is
minor seventh flat fifth (min7b5).
PRACTICE SECTION
Use the
three step method shown in the triad lesson to practise building
seventh chords as follows:
Example – make the chord
E7
Step 1 – Write the notes of the
E major scale, which would give you:
E F# G# A B C# D#.
Step 2 – Apply the formula for
(dominant) seventh chords.
The formula is
1 3 5 b7 , which gives the notes
E G# B D.
Step 3 - Find those notes anywhere on the fretboard within reach of your fingers, such as:
020100 = EBDG#BE
022130 = EBEG#DE