High Band Signals Research Articles

Cinema sound system for unperforated screens

A cinema sound system for unperforated screens includes for each stereophonic channel a floor positioned direct radiator bass speaker unit radiating into quarter space and an upper frequency speaker unit mounted above the screen. Each upper frequency speaker unit includes a middle frequency driver mounted in a sealed rear enclosure which is attached to the throat of a middle frequency horn. A constant directivity high frequency horn with a high frequency driver attached to a rear end is mounted coaxially in the middle frequency horn. Sharp cutoff active crossover filters divide the input signal into low, middle, and high frequency band signals which are separately power amplified. The middle frequency horn is adapted to function as a direct radiator at a lower end of the middle band and as a sectoral horn above an unloading frequency of the middle frequency horn. The middle frequency horn is contoured such that with the high frequency horn in place, unobstructed cross sectional areas grow exponentially from the throat to the mouth of the middle frequency horn.