Advanced-Grundkurs
A seventh chord extends a triad by a fourth note a seventh above the root. The quality of the triad and the type of seventh determine the chord type.
Major with major seventh · maj7
Major triad + major seventh. A colourful, tense sonority without an obligatory dominant function.
Dominant seventh · 7
Major triad + minor seventh. The tritone between third and seventh creates a clear tendency to resolve.
Minor seventh · m7
Minor triad + minor seventh. It combines minor colour with a relatively open seventh.
Half-diminished · m7♭5
Diminished triad + minor seventh. The diminished fifth shapes its unstable structure.
Fully diminished · dim7
Diminished triad + diminished seventh. Three minor thirds form a symmetrical chord.