Patents Assigned to Polk Investment Corporation
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Patent number: 5696357Abstract: A bass-reflex loudspeaker system includes a number of ports configured to reduce acoustic depth mode re-radiation associated with the loudspeaker cabinet during use. The length of a first port is dependent upon the interior depth of the loudspeaker cabinet and the first port is configured such that the half-wavelength resonance of the first port coincides with the half-wavelength depth mode resonance of the loudspeaker cabinet. The length of a second port is less than the length of the first port and the cross sectional area of the first port is approximately equal to the cross sectional area of the second port.Type: GrantFiled: August 25, 1995Date of Patent: December 9, 1997Assignee: Polk Investment CorporationInventor: Bradely M. Starobin
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Patent number: 5517573Abstract: 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.Type: GrantFiled: August 23, 1994Date of Patent: May 14, 1996Assignee: Polk Investment CorporationInventors: Matthew S. Polk, Colin B. Campbell
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Patent number: 5475764Abstract: 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.Type: GrantFiled: August 23, 1994Date of Patent: December 12, 1995Assignee: Polk Investment CorporationInventor: Matthew S. Polk
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Patent number: 4903300Abstract: 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.Type: GrantFiled: April 21, 1989Date of Patent: February 20, 1990Assignee: Polk Investment CorporationInventor: Matthew S. Polk
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Patent number: 4759066Abstract: 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.Type: GrantFiled: May 27, 1987Date of Patent: July 19, 1988Assignee: Polk Investment CorporationInventors: Matthew S. Polk, Colin B. Campbell
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Patent number: D350135Type: GrantFiled: January 31, 1992Date of Patent: August 30, 1994Assignee: Polk Investment CorporationInventors: Matthew S. Polk, Jr., William E. Rupert
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Patent number: D351388Type: GrantFiled: March 23, 1992Date of Patent: October 11, 1994Assignee: Polk Investment CorporationInventors: Keith A. Ballard, Allen S. Baron, Gary B. Davis, Christian H. Fink, Stuart W. Lumsden, Dale B. Rose, Peter W. Bressler
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Patent number: D351839Type: GrantFiled: March 20, 1992Date of Patent: October 25, 1994Assignee: Polk Investment CorporationInventors: Keith A. Ballard, Allen S. Baron, Gary B. Davis, Christian H. Fink, Stuart W. Lumsden, Dale B. Rose, Peter W. Bressler
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Patent number: D357480Type: GrantFiled: April 7, 1993Date of Patent: April 18, 1995Assignee: Polk Investment CorporationInventors: Stuart W. Lumsden, John D. Crisco, Matthew P. Lyons, Allen S. Baron