Chord Shapes

Dominant 7th Flat 5

Intervals: 1-3-b5-b7. An altered dominant where the perfect 5th is lowered, so the root and b5 also form a tritone. This greatly increases the sense of instability compared with a plain V7. In functional terms it still behaves as a dominant, especially in minor keys or as a secondary dominant targeting another chord by half-step or whole-step voice leading. Thinking of 7b5 as a variant of a lydian dominant or as part of a diminished/altered family helps: its b5 often resolves stepwise to the 3rd or 5th of the next chord. Use it when you want a dominant that is clearly functional but has a thinner, more brittle quality than a standard 7 or 9 chord.