Technology: Enclosure

Loudspeaker enclosures are subjected to direct driver vibration and airborne sound pressure waves. As a result they also vibrate, particularly at their natural resonant frequencies. Being relatively large, they are efficient sound radiators and their resonances colour the sound. In response most designers try to make their cabinets inert, using thick, heavy walls and bracing. Others use thin-walled materials like plywood, and, knowing that they will resonate, apply damping to reduce the effect. We take a third view: We accept cabinet vibration as inevitable, but seek not to clamp it or damp it, but to render it so evenly distributed, well-behaved and transitory as to be unperceivable.

Our 44litre enclosure uses a very low mass composite material with a hard foam core and treated paper skins. The total weight is under 1.8kg (4lbs), including no less than 16 internal braces. No wood or MDF is involved (a trial equivalent MDF cabinet weighed 26kg). For comparison, the cabinet filling itself weighs 1.0kg: So the cabinet is less than twice as heavy as its stuffing. This extremely low mass structure and the critically placed bracing results in very low stored energy levels spread evenly across a wide frequency range. Compared to conventional boxes, our cabinet has a very fast vibration decay or ring-down. A unique cabinet suspension system allows this natural controlled decay behaviour to work unhindered, providing a minimal sonic signature, with very low colouration. In effect the cabinet is inaudible.