A reflector (R) having an improved neck section that increases the useful light output of the lamp is disclosed. The reflector lamp comprises a concave reflector having a primary reflective surface with a parabolic shape, one or more intermediate reflective surfaces with a parabolic shape substantially confocal with the primary reflective surface, and an improved neck section comprising a reducing section, a first substantially straight cylindrical section, an expanding section and a second substantially straight cylindrical section.