Abstract:

At the start of recorded sound, acoustical horns were an integral part of early home audio. As electrical reproducers were developed, horns were still required because of electromechanical driver and amplifier limitations. In 1928, the wider bandwidth of the Rice--Kellogg direct radiator loudspeaker and availability of higher-power amplifiers all but removed the horn loudspeaker from home audio systems. After 1928, horn loudspeakers were only found in theater PA systems, until the introduction in the late '40s of the Klipschorn, which spawned a revival of horn loudspeakers in the 1950s. The introduction of high-power solid-state amplifiers and small bookshelf speakers in the 1960s removed horns from home audio systems. In the early '90s, the reintroduction of low-power class A tube amplifiers spurred a new interest in new horn designs. The new horn designs utilize the Tractrix horn contour for high frequencies and hyperbolic-exponential horn contours for the bass frequencies. Also, the new horn design efforts have removed colorations in the sound which plagued many of the vintage horn systems. Future horn systems will feature lighter diaphragms, better magnets, and (maybe) room temperature super conducting voice coils for higher efficiencies.