In 1981 Celestion built the hi-fi box model SL6, a compact two-way loudspeaker with a single-piece metal dome tweeter made of copper and a cone-shaped bass unit of PVC with integrated dustcap. Both speaker drivers designed with the help of laser interferometry. Afterwards followed the model SL600, which won worldwide awards in the audiophile hi-fi scene. Instead of wood for the loudspeaker enclosure a rigid honeycomb alloy called Aerolam was chosen, a material previously used only in the aerospace industry.
