WO1993014606A1 - Loudspeaker system - Google Patents
Loudspeaker system Download PDFInfo
- Publication number
- WO1993014606A1 WO1993014606A1 PCT/US1993/000151 US9300151W WO9314606A1 WO 1993014606 A1 WO1993014606 A1 WO 1993014606A1 US 9300151 W US9300151 W US 9300151W WO 9314606 A1 WO9314606 A1 WO 9314606A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- loudspeaker
- enclosure
- channel
- frequency range
- degrees
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R5/00—Stereophonic arrangements
- H04R5/02—Spatial or constructional arrangements of loudspeakers
Definitions
- the present invention relates to loudspeaker systems, and more particularly to a center channel loudspeaker system for a DOLBY PRO LOGIC home theater system.
- the Dolby system is a stereophonic system which includes surround sound encoding based upon 4-2-4 matrix methods for four-channel recording devised in the early 1970's.
- the four original signals are mixed to make a two channel stereo recording which is decoded upon playback to recover an approximation of the original four channels, which are left, center, right, and surround.
- the center channel signal is added to the left and right channels as a monophonic in-phase signal.
- the surround channel signal is added to the left and right channel signals but as an out- of-phase signal.
- the total left and total right channels are added together in a decoder to recover the center channel signal while the L-R subtraction extracts the out- of-phase surround channel signal.
- Logic steering circuitry is used upon decoding to increase the apparent separation of the left, center, right, and surround signal.
- the surround channel signal is delayed by about 20 milliseconds to prevent unwanted location of frontal sounds in the surround channel loudspeakers.
- the center channel provides most of the dialogue for a motion picture or a television program, and carries music and effects sounds as well.
- the purpose of the center channel is to insure that voices and other sounds originating from on-screen sources, will appear to come from the screen even when viewers are seated off-center.
- the center channel loudspeaker system must be capable of generating the same acoustic output levels as the left and right loudspeakers over its operating frequency range.
- center channel loudspeaker system should be located as physically close to the television screen as possible to maintain the fusion of the visual and auditory images.
- the most practical location to locate the center channel loudspeaker system in a typical living room is either on top of or underneath the television receiver. This requires that the center channel loudspeaker system be compact.
- the need for compactness, along with a minimum radiating area requirement, are important design considerations for a center channel loudspeaker system.
- the acoustic outputs from the two sources will interfere destructively causing large notches in the frequency response of the system.
- This "notching" similar to a comb filter, causes a perceptible degradation in the quality of the sound. It is desirable to minimize this destructive interference so that off axis listeners will not suffer from degraded sound quality.
- the destructive interference that occurs due to the two woofers displaced in space having the same acoustic radiation can also occur in the crossover frequency range where the woofers and tweeter are both operating. It is desirable to minimize this source of destructive interference.
- a center channel loudspeaker system for use with a Dolby four channel sound system is presented.
- a first loudspeaker is mounted at the front of an enclosure.
- Second and third loudspeakers are mounted at the front of the enclosure, one on each side of the first loudspeaker, at an angle of approximately 40 degrees in the vertical plane back from the first loudspeaker.
- FIG. 1 shows a representation of a prior art center loudspeaker system with the listeners being exposed to cancellation of sound due to destructive interference.
- FIG. 2 shows a representation of a center loudspeaker system, according to aspects of the present invention, showing how cancellation of the sound due to destructive interference is minimized.
- FIG. 1 shows loudspeaker enclosure arrangement according to the prior art.
- the loudspeaker enclosures shown are for three channels, i.e., left, right, and center, for a Dolby Pro-Logic system, with the surround loudspeakers not shown.
- the left and right stereophonic loudspeakers are any appropriate loudspeakers suitable for the purpose, and receive standard left and right signals.
- the structure and operation of the left and right stereophonic sound radiating loudspeakers form no part of the present invention and will not be discussed further.
- FIG. 1 shows a prior art center loudspeaker system comprised of a pair of 5.25 inch drivers 12 and 14 mounted within a common enclosure 16.
- Drivers 12 and 14 cover the low and middle frequency ranges.
- a horn tweeter 18, covering the high frequency range, is mounted between drivers 12, 14.
- the loudspeaker radiation would produce nulls in the combined response of the two drivers 12, 14. Only in regions A, B, and C would the response be reasonably accurate.
- the radiation from both drivers 12, 14 would be sufficiently strong to cause cancellation effects, since the path length differences between a listener in these regions and the two drivers is a significant fraction of a wavelength, or even multiple wavelengths within the similar passbands of the two drivers.
- the polar response for non-optimized loudspeakers includes wide angular spaces in which destructive interference between the acoustic radiation of drivers 12, 14 occurs.
- each of the 5.25 inch drivers 12, 14 of the exemplary embodiment are mounted at a backward angle of approximately 40 degrees, e.g., 37.5 degrees, within the vertical plane, with respect to loudspeaker 18.
- the optimum angle will be different for different sized and different frequency range loudspeakers. With such a mounting angle, as one moves off -axis to center loudspeaker 18, one moves on-axis to one of drivers 12, 14, and further off-axis to the other one of drivers 12, 14.
- horn loudspeaker 18 is mounted so that its acoustic center is approximately 4.5 cm behind the front panel of the speaker (not shown) with the optimal displacement depending on the characteristics of the particular loudspeakers used. This places the acoustic center of loudspeaker 18 in close but not in exact alignment with the acoustic centers of loudspeakers 12 and 14.
- FIG. 2 shows the approximate coverage of the two mid-woofers 12, 14 just below the frequency at which the crossover frequency for the tweeter 18 occurs in the exemplary center channel loudspeaker system.
- region A the acoustic outputs of drivers 12, 14 arrive essentially in phase and no cancellations occur.
- regions B and C the acoustic outputs of loudspeakers 12 and 14 will be shifted in phase with respect to each other.
- the net effect on the system is small because the mounting angle of loudspeakers 12, 14 significantly reduces the sound level from the further loudspeaker with respect to the nearer loudspeaker.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1019940702326A KR940704110A (en) | 1992-01-08 | 1993-01-08 | Loudspeaker system |
EP93903022A EP0639317A1 (en) | 1992-01-08 | 1993-01-08 | Loudspeaker system |
JP5512588A JPH07503112A (en) | 1992-01-08 | 1993-01-08 | speaker system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB929200302A GB9200302D0 (en) | 1992-01-08 | 1992-01-08 | Loud speaker systems |
GB9200302.9 | 1992-01-08 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1993014606A1 true WO1993014606A1 (en) | 1993-07-22 |
Family
ID=10708255
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1993/000151 WO1993014606A1 (en) | 1992-01-08 | 1993-01-08 | Loudspeaker system |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0639317A1 (en) |
JP (1) | JPH07503112A (en) |
KR (1) | KR940704110A (en) |
CA (1) | CA2117383A1 (en) |
GB (1) | GB9200302D0 (en) |
WO (1) | WO1993014606A1 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1427254A3 (en) * | 2002-12-03 | 2006-11-02 | Bose Corporation | Electroacoustical transducing with low frequency aufmenting devices |
US8045743B2 (en) | 2005-09-12 | 2011-10-25 | Bose Corporation | Seat electroacoustical transducing |
US8139797B2 (en) | 2002-12-03 | 2012-03-20 | Bose Corporation | Directional electroacoustical transducing |
US8483413B2 (en) | 2007-05-04 | 2013-07-09 | Bose Corporation | System and method for directionally radiating sound |
US9100748B2 (en) | 2007-05-04 | 2015-08-04 | Bose Corporation | System and method for directionally radiating sound |
EP3041265A3 (en) * | 2014-09-08 | 2016-07-20 | Adamson Systems Engineering Inc. | Loudspeaker with improved directional behavior and reduction of acoustical interference |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
RU2013158172A (en) * | 2011-06-09 | 2015-07-20 | Конинклейке Филипс Н.В. | DEVICE FOR AUDIO SPEAKERS |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2143175A (en) * | 1937-10-23 | 1939-01-10 | Samuel A Waite | Sound reproducing system |
US3026957A (en) * | 1959-06-02 | 1962-03-27 | Gladstone Lewis | Loudspeaker system |
US4073365A (en) * | 1977-07-11 | 1978-02-14 | Johnson Joseph W | Speaker system |
US4888804A (en) * | 1988-05-12 | 1989-12-19 | Gefvert Herbert I | Sound reproduction system |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3983333A (en) * | 1974-03-01 | 1976-09-28 | Allison Acoustics Inc. | Loud speaker system |
JPS54148501A (en) * | 1978-03-16 | 1979-11-20 | Akg Akustische Kino Geraete | Device for reproducing at least 2 channels acoustic events transmitted in room |
FI81471C (en) * | 1988-11-08 | 1990-10-10 | Timo Tarkkonen | HOEGTALARE GIVANDE ETT TREDIMENSIONELLT STEREOLJUDINTRYCK. |
-
1992
- 1992-01-08 GB GB929200302A patent/GB9200302D0/en active Pending
-
1993
- 1993-01-08 JP JP5512588A patent/JPH07503112A/en active Pending
- 1993-01-08 EP EP93903022A patent/EP0639317A1/en not_active Withdrawn
- 1993-01-08 WO PCT/US1993/000151 patent/WO1993014606A1/en not_active Application Discontinuation
- 1993-01-08 CA CA002117383A patent/CA2117383A1/en not_active Abandoned
- 1993-01-08 KR KR1019940702326A patent/KR940704110A/en not_active Application Discontinuation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2143175A (en) * | 1937-10-23 | 1939-01-10 | Samuel A Waite | Sound reproducing system |
US3026957A (en) * | 1959-06-02 | 1962-03-27 | Gladstone Lewis | Loudspeaker system |
US4073365A (en) * | 1977-07-11 | 1978-02-14 | Johnson Joseph W | Speaker system |
US4888804A (en) * | 1988-05-12 | 1989-12-19 | Gefvert Herbert I | Sound reproduction system |
Non-Patent Citations (1)
Title |
---|
See also references of EP0639317A4 * |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1427254A3 (en) * | 2002-12-03 | 2006-11-02 | Bose Corporation | Electroacoustical transducing with low frequency aufmenting devices |
US7676047B2 (en) | 2002-12-03 | 2010-03-09 | Bose Corporation | Electroacoustical transducing with low frequency augmenting devices |
US8139797B2 (en) | 2002-12-03 | 2012-03-20 | Bose Corporation | Directional electroacoustical transducing |
US8238578B2 (en) | 2002-12-03 | 2012-08-07 | Bose Corporation | Electroacoustical transducing with low frequency augmenting devices |
US8045743B2 (en) | 2005-09-12 | 2011-10-25 | Bose Corporation | Seat electroacoustical transducing |
US8483413B2 (en) | 2007-05-04 | 2013-07-09 | Bose Corporation | System and method for directionally radiating sound |
US9100748B2 (en) | 2007-05-04 | 2015-08-04 | Bose Corporation | System and method for directionally radiating sound |
US9100749B2 (en) | 2007-05-04 | 2015-08-04 | Bose Corporation | System and method for directionally radiating sound |
EP3041265A3 (en) * | 2014-09-08 | 2016-07-20 | Adamson Systems Engineering Inc. | Loudspeaker with improved directional behavior and reduction of acoustical interference |
US9706289B2 (en) | 2014-09-08 | 2017-07-11 | Adamson Systems Engineering Inc. | Loudspeaker with improved directional behavior and reduction of acoustical interference |
Also Published As
Publication number | Publication date |
---|---|
EP0639317A1 (en) | 1995-02-22 |
GB9200302D0 (en) | 1992-02-26 |
KR940704110A (en) | 1994-12-12 |
JPH07503112A (en) | 1995-03-30 |
CA2117383A1 (en) | 1993-07-22 |
EP0639317A4 (en) | 1994-10-17 |
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