Technology & Engineering

Super Cell Aerated Polypropylene

Picture the frustration of the speaker cone designer. The best speaker cone material would be stiff and rigid, to maintain its integrity and shape throughout the constant high speed back-and-forth motion without distorting. To move quickly, it needs to be extremely lightweight. And to keep this lightweight, stiff material from “ringing” with vibrations it should also be damped. But damping adds weight and softness, so you’re right back where you started. No wonder there’s an industrial-sized bottle of aspirin next to the water cooler in the engineering department.

The search for every more perfect cone materials has consumed Polk engineers since the beginning. No existing materials reproduced sound at all frequencies exactly the way we wanted to hear it: natural and uncolored. Years of fundamental research into the nature of materials and design, including our pioneering Dynamic Balance® Materials Tuning process, have helped us produce a completely new array of breakthrough materials that, amazingly, have the lightweight rigidity we demand, and the damping qualities we need.

The first breakthrough was our Aerated Polypropylene cone material. This advanced material is strong, lightweight and non-resonant. It plays a big part in the natural, transparently realistic reproduction of the award-winning LSi Series.

In designing the transducers for the new LSiM series, Polk engineers developed a process enhancement to the Aerated Polypropylene that exponentially improves performance. This Super Cell Aerated Polypropylene, like its predecessor, uses a proprietary process to “puff up” the foam-like filling between the two extremely rigid outer layers of the material. However, in the new process, the irregularity in the positions and sizes of the microscopic pockets of air results in a cone material that is still exceptionally stiff and non-resonant but weighing even less.

You can hear Super Cell Aerated Polypropylene cones at work in the flagship LSiM Series of Polk loudspeakers. Listen for (and be astounded by) their natural, engagingly transparent performance.

This article was last modified on Jul 10, 2012

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