Trenner & Friedl Duke
Each 12" woofer uses a fiber-glassreinforced paper cone and is loaded by what is referred to as "a hybrid form of horn-resonator and bass reflex design." The mid/HF module is coupled to the woofer modules with spheres of varying hardness, to drain vibrations optimally, and can be adjusted to bring the drivers into proper time alignment at the listening position. The midrange unit features a papyrus cone with an elmwood phase plug and an alnico magnet, while the enclosure is filled with wool from "locally raised sheep" to reduce internal reflections being retransmitted through the drive-unit cone. The tweeter uses a titanium nitride dome loaded with a Tractrix-flare horn, while the supertweeter is a diamond-diaphragm type. The upper-range crossover is passive; the woofers are fed via a line-level crossover, and internal wiring is all Cardas Clear.