Seventh chords are an emotive way of adding depth and dimension to music, commonly seen in jazz, blues and film genres.
To fully comprehend these chords, one must know how they’re put together. We’ll begin by exploring the fundamental structure of a seventh chord.
Major 7th
The major 7th chord can be formed by adding a major seventh to a major triad, and is the chord most frequently seen in pop and rock music, but can also be found in jazz music. With its attractive sound and versatility, this chord can also be found within jazz music genres.
Construction of this chord is extremely straightforward; like triads, seventh chords consist of three stacked thirds: root, middle and fifth. In fact, major seventh chords can simply be seen as major triads with another major seventh added on top!
Note that, when creating a major seventh chord, its seventh note should always be played as a 6 instead of 7. This is done to avoid dissonant notes that would otherwise clash against the melody note; by comparison, playing through major scales with this harmony will help you hear this difference! Also keep in mind there are other types of triads which have their sevenths flattened to produce half-diminished chords such as minor 7 flat 5. These types are less commonly found and utilized in western music.
Minor 7th
Minor seventh chords feature an emotive “sad” quality that adds depth and color to music. Learning this chord can help create tension and release at the same time; typically resolving with either falling fifth (or rising fourth) root motion; this explains why so many blues musicians use V7 chords as turnarounds.
An easy way to construct a minor 7th chord is by lowering both third and seventh of an existing major seventh chord by half steps – you can find this information on the note interval chart at Major-7th Chord Intervals.
Like with triads, minor sevenths can be composed by stacking any combination of 3rds and 7ths above a minor triad to form it. Just be sure to include any accidentals from the key signature of the minor scale that apply in order to form the appropriate chord!
Dominant 7th
If you have ever seen a chord ending with 7 in its name, that could be a dominant seventh chord. These chords are created by adding a fourth note that is one minor 7th interval above the root chord and tend to produce dissonant 3rd and 7th notes that give them their characteristic dissonant sound; jazz composers such as Wayne Shorter often employ this style of chord to add floating sense of ambiguity into their compositions.
Assuming your major triad is in diatonic harmony, constructing a dominant seventh chord requires counting up three half steps (or one whole step from your root octave above and lowering by half step) from its root note (or alternatively counting up one whole step from there and then lowering seventh note by half step). Remember that functional chord symbols represent diatonic harmony.
Half-diminished 7th
A half diminished 7th chord is a minor seventh chord with an inverted fifth note that features a flattened 5th. It is less popular than major or minor 7th chords and typically found as connecting chords; it can be built using any scale degree, however most commonly found in minor keys.
To create a half diminished 7th chord, begin with a minor seventh flat five triad and add an interval number in brackets that indicates which scale note names to use as you add the diminished fifth interval above it. When building half diminished 7th chords it’s essential that they start from within your key’s triad chart as this allows for easy reference when selecting scale note names for building the chords.
Complete triads consist of the root, major 3rd, and minor 7th notes; additionally a diminished seventh is added in similar fashion but with its own name to easily differentiate them from fully diminished 7th chords.