In 1984, the former Backes & Müller production engineer, Berhard Thiel, invented an electrochemical process to produce very thin sheets of extremely hard Corundum. This patented process yielded the manufacture of a very rigid, light weight, and highly damped speaker diaphragm.

These diaphragms of Al²O³ in a Sapphire lattice prove to have high internal damping, which is unusual for such a hard material. The stiffness/weight ratio of this material is unsurpassed, excluding Diamond, which is necessary for accurate impulse response. The diaphragms exhibit high internal sound velocity important for elevating breakup frequencies and extending linear range. These features are essential for extremely low coloration and distortion. The well balanced concave shape yields uniformed energy distribution as opposed to merely high on-axis SPL. The front plate is made of heavy, acoustically inert, zinc instead of plastic or aluminum. All mechanical parts are manufactured to very close tolerances.

As you can imagine, this is not a simple process. The process is slow and costly, making the price of Accuton drivers quite a bargain. Accuton has gained a remarkable reputation in the Audiophile realm. In commercially available loudspeakers, these drivers are exclusively found in the Ultra High-End!