Audio system with amplifier and signal device

DETAILED DESCRIPTION The present invention provides a sound system which is particularly adapted for use with such an unperforated movie screen.
The system includes a bass speaker unit and a mid-to-high or upper frequency speaker unit for each stereophonic channel of the sound track format employed.
The bass speaker units function as direct radiators and are arrayed across the screen and are positioned on a floor therebelow.
The upper frequency speaker units are placed above the screen in general alignment with the bass speaker units and are oriented to optimally acoustically excite the audience seating area of the theater.
Each upper frequency speaker unit includes a middle frequency horn and driver and a coaxially mounted high frequency horn and driver.
The middle frequency driver is mounted in a sealed rear enclosure which is attached to the throat of the middle frequency horn.
The high frequency horn has its driver attached thereto and the combination is mounted along the projection axis of the middle frequency driver on posts extending across the mouth of the middle frequency horn.
The high frequency horn is a constant directivity type horn and has a dispersion pattern of about 90 degrees laterally by 40 degrees vertically.
The middle frequency horn is adapted to function as a direct radiator below an unloading frequency thereof and increasingly as a sectoral horn above the unloading frequency.
The middle frequency horn is contoured such that with the high frequency horn in place, unobstructed cross sectional areas of the middle frequency grow exponentially.
The system according to the present invention includes active crossovers for dividing each main sound track signal into a low frequency band, a middle frequency band, and a high frequency.
The crossover filters are sharp cutoff filters, such as fourth order Butterworth filters.
The high frequency path includes a delay circuit to compensate for delay introduced in the middle frequency signal due to the physical positioning of the drivers in the upper frequency unit