Rockport Technologies has long been a pioneer in developing innovative methods of cabinet construction, but the company pulled out all the stops for the Lyra. No other speaker enclosure has ever been built to this level of sophistication.
For many years Rockport has eschewed making cabinets from flat sheet stock in favor of advanced molding techniques. For example, the enclosure of Rockport’s Altair (see my review in Issue 214) is made from an inner and outer fiberglass shell, with the void between them filled with dense epoxy (see photo, a cross-section of the Altair’s cabinet, on the following page). This method not only creates a stiff and dense enclosure, it also allows cabinet shapes optimized for acoustic performance without the limitations imposed by gluing together flat sheets of material. An added benefit is a seamless monocoque structure with no joinery.
For the Lyra, Rockport has taken this concept to an extreme. Rather than make the inner and outer shells from fiberglass or even carbon-fiber, the Lyra’s two “shells” are massive cast-aluminum structures. The inner enclosure fits inside the outer enclosure, the joint is sealed, and then the cavity is filled with a proprietary, high density, highly damped urethane core material. The inner enclosure (which is also the baffle) is an intricately designed casting with extensive reinforcement structures inside to brace the drivers. Rockport created a 3-D animated video showing this technique (available on YouTube). The company calls this construction technique “Damstif,” which appears to be exceptionally dense, stiff, and well damped and should reduce enclosure vibration to levels never before realised.