Abstract: Disclosed exemplary solid state light fixtures use optical cavities to combine or integrate light from LEDs or the like. In such a fixture, the cavity is formed by a light transmissive structure having a volume, and a diffuse reflector that covers a contoured portion of the structure. A heat sink member supports a flexible circuit board so as to position the light emitters to couple light to the transmissive structure and provide effective heat dissipation. The circuit board has flexible tabs mounting the emitters. When installed in the fixture, the tabs bend and the emitters press against a sufficiently rigid periphery of the light transmissive structure. TIM may be compressed between the heat sink member and the opposite surface of each tab. Heat conductive surface pads and heat conductors through vias through the tabs conduct heat from the emitters to the heat sink member, e.g. through the TIM.