Abstract: A direct field acoustic testing system comprising a control microphone, a controller operatively coupled to the control microphone such that the controller receives at least one input signal from the control microphone, and a plurality of acoustic transducer groups receiving an electronic signal from the controller, each transducer group including at least one acoustic transducer. An average power density of the direct field acoustic testing system for a pre-determined acoustic test spectrum being equal to or greater than 46 acoustic watts per square meter of total active acoustic transducer radiating surface area.

Abstract: A compact audio reproduction system for two input signals includes at least four loudspeakers disposed at the vertices of a quadrilateral not more than two feet on any side and such that no two loudspeakers are located at a distance from one another which is less than one-fourth the greatest distance between any two loudspeakers. The two input signals are connected to alternate speakers such that no two loudspeakers at adjacent vertices of the quadrilateral produce the same signal such that a listener at an arbitrary location perceives a sound source larger than the quadrilateral and significant stereo image. The signals received by two loudspeakers located at adjacent vertices may receive signals which are equalized separately from the signals received by the other loudspeakers for the purpose of reducing comb filtering and improving the tolerance of the device to placement near walls and other obstructions.

Abstract: In a loudspeaker system with main and sub-speakers, a modified and inverted left surround signal is added to the signals driving the right main speaker and a modified and inverted right surround signal is added to the signals driving the Left Main Speaker for the purpose of creating more credible rear located phantom sound images. In a system using variations of a difference signal to create phantom rear located sound images, the components of the difference signal are modified by introducing a time delay to one of the components for the purpose of preventing the components of the difference signal from substantially canceling each other. The components of the difference signal may be modified by altering the relative level and frequency response of the components for the purpose of preventing the components of the difference signal from substantially canceling each other.

Abstract: A loudspeaker system includes a cabinet with an interior air volume, a transducer, a first port extending from an opening in the front wall of the cabinet to the interior of the cabinet, and a second port extending from and opening in the rear wall of the cabinet to the interior of the cabinet. The first and second ports are aligned along a common longitudinal axis and the interior ends of the ports are separated from each other by a predetermined distance. First and second flanges having a diameter larger than the first and second ports are disposed at the interior ends of the first and second ports, respectively.

Abstract: A port for a loudspeaker is disclosed which is sufficiently weather resistant for long term outdoor use and which prevents debris, insects and other vermin from entering the loudspeaker and which is compact and efficient.

Abstract: A surround sound reproduction system uses a series of filters and a system of main and sub-speakers to produce phantom rear surround sound channels or a phantom surround sound effect from a loudspeaker system or pair of loudspeaker systems located in front of the listener. The sound system includes left and right surround input signals, and left and right front input signals. Left and right sub-speakers, and left and right main speakers are located in front of a listening location. Spacing between respective main and sub-speakers is approximately equal to ear spacing for an average person. The input to the left sub-speaker comprises the right surround signal subtracted from the left surround signal each signal having previously passed through a front-to-back filter and a series of high and low pass filters. The input into the left main speaker comprises the left front signal added to the left surround signal after the left surround signal has passed through a front-to-back filter.

Abstract: A loudspeaker system includes a cabinet with an interior air volume, a transducer, a first port extending from an opening in the front wall of the cabinet to the interior of the cabinet, and a second port extending from and opening in the rear wall of the cabinet to the interior of the cabinet. The first and second ports are aligned along a common longitudinal axis and the interior ends of the ports are separated from each other by a predetermined distance. First and second flanges having a diameter larger than the first and second ports are disposed at the interior ends of the first and second ports, respectively.

Abstract: A mounting system for loudspeakers is provided. In general, the system comprises a flexible arm having a first end and a second end. The first end of the flexible arm is suitably mounted to the loudspeaker. The second end of the flexible arm is suitably mounted to a surface. The surface may comprise a wall, another loudspeaker and/or a computer monitor. Various combinations and arrangements of speakers are disclosed, including mounting systems advantageously configured to provide surround sound experiences.

Abstract: A mounting system for loudspeakers is provided. In general, the system comprises a flexible arm having a first end and a second end. The first end of the flexible arm is suitably mounted to the loudspeaker. The second end of the flexible arm is suitably mounted to a surface. The surface may comprise a wall, another loudspeaker and/or a computer monitor. Various combinations and arrangements of speakers are disclosed, including mounting systems advantageously configured to provide surround sound experiences.

Abstract: A vent loudspeaker system is provided which has at least one active driver and a port opening in a speaker cabinet. Disks or baffle plates are mounted a predetermined distance to and concentric to the port opening, resulting in a vented system achieving an equivalent performance as would result from a flared, ducted port, but with several performance advantages and simpler construction.

Abstract: A vented loudspeaker system is provided which has at least one active driver and a port opening in a speaker cabinet, Disks or baffle plates are mounted a predetermined distance to and concentric to the port opening, resulting in a vented system achieving an equivalent performance as would result from a flared, ducted port, but with several performance advantages and simpler construction. Flow guides are provided, attached to the disks or baffle plates, extending back into the port to block areas of stagnant air and enhance laminar air flow.

Abstract: A single-vented bandpass woofer loudspeaker system design and method for enabling operation in smaller enclosure volumes with only moderate loss of efficiency. The bandpass system has an enclosure with a partition dividing it into a first sealed chamber and a second chamber having a passive radiating port communicating with air outside the enclosure. A driver is mounted in the partition. Novel, empirically determined tuning ratios which depend upon system variables are defined. By adjusting the system variables to keep the tuning ratios within empirically determined values, a good relationship between flat response, bandwidth and efficiency is achieved. Unexpectedly, using a higher than normal moving mass of the driver leads to an acceptable system with a very small enclosure volume.

Abstract: A loudspeaker system is provided for installation in a space between a front panel and an enclosed area behind the front panel of a partition such as a wall, ceiling or floor fronting a listening area. Electroacoustical transducers are provided which have a two sided vibratory diaphragm driven by an electrical signal. An enclosure mounts the electroacoustical transducers such that one side of the vibratory diaphragm is in contact with air outside the enclosure, with the enclosure being configured to substantially enclose and define a specific volume of air within the enclosure having a predefined acoustic compliance and which is in contact with the other side of the vibratory diaphragm of the electroacoustical transducers.

Abstract: A loudspeaker system is provided for installation in a space between a front panel and an enclosed area behind the front panel of a partition such as a wall, ceiling or floor fronting a listening area. Electroacoustical transducers are provided which have a two sided vibratory diaphragm driven by an electrical signal. An enclosure mounts the electroacoustical transducers such that one side of the vibratory diaphragm is in contact with air outside the enclosing between the front and rear panels of the partition, with the enclosure being configured to substantially enclose and define a specific volume of air within the enclosure having a predefined acoustic compliance and which is in contact with the other side of the vibratory diaphragm of the electroacoustical transducers.

Abstract: A loudspeaker system for reproducing stereophonic sound having an expanded acoustic image has left and right main speakers and left and right dimensional speakers. The main speakers are fed the right and left channel signals R and L and the dimensional speakers are fed the difference signals R - L and L - R. Interspeaker cabling includes one or more transformers used to develop and couple the difference signals to the dimensional speakers, which serve as isolation means and also suppress the -R and -L components of the difference signals for low frequencies. The loudspeaker system is particularly suited for automobile installations where the main speakers are in front and the dimensional speakers in the rear of the automobile interior, or vice versa.

Abstract: A loudspeaker system for use with a stereo system having right R and left L signal outputs, has a right main speaker and right sub-speaker, and a left main speaker and left sub-speaker. Inter-speaker cabling means, which connect to the R and L signal outputs, apply an R signal to the right main speaker and an R-L signal to the right sub-speaker, as well as an L signal to the left main speaker and an L-R signal to the left sub-speaker. The inter-speaker cabling means includes impedances for substantially attenuating the -R portion of the L-R signal and the -L portion of the R-L signal for signal frequencies below approximately 200 Hz.

Abstract: Apparatus for reproducing sound having a realistic ambient field and acoustic image is used in a stereophonic sound reproduction system having a left channel output and a right channel output. A right main speaker and a left main speaker are disposed at right and left main speaker locations, respectively, which are equidistantly spaced from a listening location along a listening axis perpendicular to a line joining the left and right main speakers. A right sub-speaker and a left sub-speaker are respectively disposed at right and left sub-speaker locations equidistantly spaced from the listening location, and further from the listening location than the main speaker. In one particular arrangement each main speaker includes a driver and a tweeter and each sub-speaker includes only a driver. The left and right channel outputs are respectively coupled to the left and right main speakers.

Abstract: Apparatus for reproducing sound having a realistic ambient field and acoustic image is used in a stereophonic sound reproduction system having a left channel output and a right channel output. A right main speaker and a left main speaker are disposed at right and left main speaker locations, respectively, which are equidistantly spaced from a listening location along a listening axis perpendicular to a line joining the left and right main speakers. A right sub-speaker and a left sub-speaker are respectively disposed at right and left sub-speaker locations equidistantly spaced from the listening location, and further from the listening location than the main speaker. In one particular arrangement each sub-speaker includes a driver and a tweeter, with the driver spaced a distance approximately 50% further from the main speaker location than the tweeter. The left and right channel outputs are respectively coupled to the left and right main speakers.

Abstract: Apparatus for reproducing sound having an expanded acoustic image is used in a stereophonic sound reproduction system having a left channel output and a right channel output, which need not be binaural. A right main speaker and a left main speaker are disposed at right and left main speaker locations, respectively, which are equidistantly spaced from a listening location along a listening axis perpendicular to a line joining the left and right main speakers. The interaural time delay between the ears of a listener at the listening location with respect to the main speakers is .DELTA.t. A first right sub-speaker and a first left sub-speaker are respectively disposed at right and left sub-speaker locations equidistantly spaced from the listening location, and spaced such that sound from the sub-speakers as perceived by the ears of a listener is delayed as compared to sound from the main speakers by .DELTA.t. The left and right channel outputs are coupled to the left and right main speakers, respectively.