803 D4 may be notably more compact than the 801 D4 or 802 D4, but it still bristles with technical innovation, most obviously in its use of a three-box construction. Its 130mm (5in) midrange cone is carefully isolated from the impact of its bass cones thanks to its Turbine Head enclosure. Instead of a conventional loudspeaker box, our cabinets are made from a continuous curved section of wood, with the drive units mounted at the heart of the curvature. This stiffer, more inert structure resists mechanical resonances far better and also ensures better dispersion of sound. Matrix bracing uses interlocking panels to reinforce loudspeaker cabinet walls in all directions internally, reducing resonance and creating a more believable soundstage. The Matrix assembly in 803 D4 is our best yet, ensuring optimum scale, power and intelligibility.