Loudspeaker array system
View Patent ↗The invention is a multi-channel loudspeaker system that provides a compact loudspeaker configuration and filter design methodology that operates in the digital signal processing domain. Further, the loudspeaker system can be designed as a multi-way loudspeaker system comprised of a symmetric arrangement of loudspeaker drivers in a two-dimensional plane and can achieve high-quality sound, constant directivity over a large area in both the vertical and horizontal planes and can be used in connection with stereo loudspeaker systems, multi-channel home entertainment systems and public address systems.
1. A loudspeaker array comprising:
at least one digital FIR filter configured to receive a digital audio signal from an audio sound source;
at least one power D/A converter configured to receive a filtered signal from the at least one FIR filter, where the at least one digital FIR filter includes linear phase filter coefficients determined for optimized transducer positions; and
a plurality of transducers of at least two different sizes, the plurality of transducers arranged symmetrically about a first axis and about a second axis perpendicular to the first axis at optimized transducer positions determined and optimized using a cost minimization function to determine a minimum difference between a desired performance of the loudspeaker array indicated by a directivity target function and a measured frequency response, the plurality of transducers coupled to the at least one power D/A converter.
2. The loudspeaker array of claim 1 where the at least two different sizes of the plurality of transducers are tweeters and midrange drivers.
3. The loudspeaker array of claim 1 where the at least two different sizes of the plurality of transducers are tweeters and woofers.
4. The loudspeaker array of claim 1 where the plurality of drivers include tweeters, midrange drivers and woofers.
5. The loudspeaker array of claim 1 further comprising a center transducer positioned with its center at the intersection of the first and second axis.
6. The loudspeaker array of claim 5 where the center transducer receives a signal from at least one power D/A converter that has been filtered through at least one digital FIR filter.
7. The loudspeaker array of claim 1 where the linear phase filter coefficients for each FIR filter is determined by establishing the initial driver positions; establishing the initial directivity target functions for the system; applying the cost minimization function based upon the initial directivity target function; and computing linear phase filter coefficients for each filter in the system.
8. The loudspeaker array of claim 7 where the initial driver positions are coordinates relative to the center of origin of the loudspeaker.
9. The loudspeaker array of claim 7 , where frequency points are established on a logarithmic scale with a predetermined frequency range based upon the established initial directivity target functions.
10. The loudspeaker array of claim 7 , where the cost minimization function is applied at the frequency points, starting with the lowest frequency increment stepwise.
11. The loudspeaker array of claim 7 , where the Fourier approximation method is utilized to establish the linear phase filter coefficients.
12. A loudspeaker system comprising:
at least one digital FIR filter configured to receive a digital audio signal from an audio sound source;
at least one power D/A converter configured to receive a filtered signal from the at least one FIR filter, where the at least one digital FIR filter includes linear phase filter coefficients determined for optimized transducer positions; and
at least five transducers of at least two different sizes, four of the at least five transducers symmetrically arranged about both a first axis and a second axis perpendicular to the first axis, and one transducer centered at the intersection of the first and second axes, the symmetrically arranged transducers positioned at optimized transducer positions determined and optimized using a cost minimization function to determine a minimum difference between a desired performance of the loudspeaker array indicated by a directivity target function and a measured frequency response, the plurality of transducers configured to receive an audio signal output from. the at least one power D/A converter.