Abstract A loudspeaker system includes a loudspeaker mounted in an enclosure, the enclosure having a front port for exiting the sound energy radiated by the front of the speaker cone and a port, or ports, or other areas for exiting the sound energy radiated by the rear of the speaker cone which is out of phase with the front radiation. The port, ports or areas through which the energy from the back cone surfaces is radiated is made acoustically resistive so as to delay the sound energy in conjunction with the acoustic compliance of the enclosure. The dimensions of the enclosure, the effective resistivity, and the total area from which the speaker rear energy is radiated are chosen so that the sound energy from the rear of the speaker cone effectively cancels out sound arriving from the front of the speaker cone at regions to the rear of the enclosure. This minimizes the effective acoustical energy to the rear of the loudspeaker system so as to make for a forwardly directed sound radiation pattern.
A speaker system comprising: a speaker member having a cone with front and rear portions for radiating acoustical energy in phase opposition relationship and an enclosure in which said speaker is mounted, said enclosure having a port formed therein for exiting the acoustical energy radiated by the front portions of said cone to the front of said enclosure, the improvement comprising: a pair of similar ports formed in the sides of said enclosure for exiting a predetermined amount of energy radiated by the rear portion of said cone, and resistive material for providing a predetermined acoustical resistance covering said ports so as to time delay the acoustical energy exited from said ports, said ports having a predetermined area, said enclosure having a predetermined volume, and said resistive means providing a predetermined acoustical resistance such that the acoustical energy exiting from said ports within a predetermined frequency range effectively reduces the acoustical energy radiated by the front portions of said cone within said frequency range at substantially all points to the rear of said speaker enclosure.
Claim 2
Dependent Claim
175 words
A speaker system comprising: a speaker member having a cone with front and rear portions for radiating acoustical energy in phase opposition relationship and an enclosure in which said speaker is mounted, said enclosure having a port formed therein for exiting the acoustical energy radiated by the front portions of said cone to the front of said enclosure, the improvement comprising: a pair of similar ports formed in the sides of said enclosure for exiting a predetermined amount of energy radiated by the rear portion of said cone, and resistive material for providing a predetermined acoustical resistance covering said ports so as to time delay the acoustical energy exited from said ports, said ports having a predetermined area, said enclosure having a predetermined volume, and said resistive means providing a predetermined acoustical resistance such that the acoustical energy exiting from said ports within a predetermined frequency range effectively reduces the acoustical energy radiated by the front portions of said cone within said frequency range at substantially all points to the rear of said speaker enclosure.
Claim 3
Dependent Claim
112 words
The device of claim 1 wherein the acoustical radiation pattern of said speaker system within a predetermined frequency range is a hypercardioid and the total effective area, A, of said port means is in accordance with the following equation: A RV/ Rho c2 Tau where: R is the specific acoustic resistance of the exit port material, V is the volume of the enclosure, Rho is the density of air, c is the velocity of sound and air, and Tau Delta x/3c, where Delta x is the effective acoustical path length from the front side of the speaker cone to the apparent point of radiation of the sound exited by the port means.