THE HORN PROBLEM

摘要

KEF began using the Uni-Q driver array in 1988. Enabled by the development of neodymium-iron-boron magnet materials, which allowed a sufficiently powerful tweeter magnet to be made much smaller than with ferrite, the Uni-Q array was the first melding of a dome tweeter and cone midrange or bass-midrange driver that was both coaxial and coincident, since the two elements were naturally time-aligned. A decade earlier Siegfried Linkwitz had cast a light on the vertical off-axis behaviour of speakers with non-coincident drive units, and it was becoming clear that, ideally, a speaker should have well-controlled directivity in all directions through crossover, to prevent intrusive spectral disparities between its direct sound and the early reflections and reverberant sound from the listening room. Uni-Q addressed such issues, but by placing the tweeter at the apex of the cone it also opened itself up to the traditional problems of horn loading, notably coloration-inducing reflections from the horn mouth. This latest Uni-Q design comes a big step closer to eliminating these.