A light fixture comprising a chamber portion is disclosed. In some embodiments, the fixture comprises a chamber portion shaped to house circuitry required for lighting elements such as light emitting diodes (LEDs) mounted elsewhere in the fixture. In some embodiments, LEDs are mounted facing a back reflector, which in turn reflects light out of a troffer to form an indirect lighting fixture. In some embodiments, light is emitted from one mixing chamber. In some embodiments, light is emitted from two or more mixing chambers. In some embodiments, LEDs are mounted on a heat sink which cooperates with a chamber portion.