BMC's Arcadia Speakers
The sealed enclosure is constructed from two clamshells of a alumina-based ceramic with an acrylic binder, welded together. This material is said to combine high stiffness with good self-damping and is also used for the external crossover. The woofers use a cone constructed from a sandwich of Kevlar-honeycomb-Kevlar. The tweeter is an AMT-style unit and is claimed to have a high sensitivity of 105dB; usually, the tweeter is the limiting factor in a system's sensitivity, meaning the lower-frequency drivers have to attenuated to match. In this case, it is the tweeter that is potted down, to give a system figure of 91dB/2.83/m, with a 4 ohm impedance.