A premix burner for a heat generator has partial cone shells (5) which make up a vortex generator, and which encompass a conically widening vortex chamber (6) and mutually define tangential air inlet slots (7), and also with feeds for gaseous and/or liquid fuel, of which at least one is arranged along the air inlet slots (7) on the partial cone shells (5), and at least one other is arranged along a burner axis (A) which centrally passes through the vortex chamber (6). At least n partial cone shells (5) encompass the vortex chamber (6), and define n air inlet slots (7), with n≧3, preferably n≧5, the n air inlet slots (7) each have at least a maximum slot width (10) which is equal to or larger than that slot width (10) which a generic type premix burner (1) of the same size and dimensioning with m≦2 partial cone shells (5) and m air inlet slots (7) has.