US2097289A - Acoustic apparatus - Google Patents
Acoustic apparatus Download PDFInfo
- Publication number
- US2097289A US2097289A US758374A US75837434A US2097289A US 2097289 A US2097289 A US 2097289A US 758374 A US758374 A US 758374A US 75837434 A US75837434 A US 75837434A US 2097289 A US2097289 A US 2097289A
- Authority
- US
- United States
- Prior art keywords
- loudspeaker
- acoustic
- orifices
- cavities
- cabinet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000005192 partition Methods 0.000 description 6
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only
- H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
- H04R1/2807—Enclosures comprising vibrating or resonating arrangements
- H04R1/2815—Enclosures comprising vibrating or resonating arrangements of the bass reflex type
- H04R1/2823—Vents, i.e. ports, e.g. shape thereof or tuning thereof with damping material
- H04R1/2826—Vents, i.e. ports, e.g. shape thereof or tuning thereof with damping material for loudspeaker transducers
Definitions
- This invention relates to acoustic apparatus. More specifically it relates to apparatus for the elimination of cabinet resonance resulting from a loudspeaker or the like being enclosed in a 5; cabinet such as a radio cabinet.
- these frequencies which are referred to as the natural resonant periods of the system, the acoustic output of the loudspeaker and associated system is considerably greater than at frequencies on either side of the resonant frequencies. This effect leads to non-uniform response over the frequency range and to a decrease in the fidelity of the system.
- the acoustic impedance into which the back of the loudspeaker feeds is made such that sound will be transmitted therethrough without attenuation.
- FIG. 1 illustrates diagrammatically an arrangement for the elimination of resonance frequencies in the box enclosing the back of a loudspeaker diaphragm
- Fig. 2 is the electrical analog of the construction shown in Fig. 1
- Fig. 3 illustrates how the invention may be applied to a loudspeaker mounted in a radio cabinet.
- the loudspeaker is mounted in a box which encloses the back of the diaphragm.
- the driving mechanism has been omitted, but the diaphragm is illustrated at I0.
- the box II which encloses the loudspeaker, contains a plurality of panels I2a, I22), I20, IZd, and He, arranged substantially parallel with the front wall 13 in which the diaphragm I0 is mounted.
- Each of the panels I20, I21), I20, IM and I26 contains an orifice Ma, Mb, I40, Md and Me.
- the panels are spaced from the wall 13 and from each other to form cavities C1, C2, C3, C4, C5.
- the orifices constitute acoustic inertance m1, m2, m3, m4 and ms.
- the cavities formed by the par- 65 tltions constitute acoustic impedances.
- Fig. 1 The operation of the apparatus illustrated in Fig. 1 can be determined by referring to the circuit of Fig. 2 which is the electrical analog of the apparatus of Fig. 1.
- Z0 represents the'impedance of the opening in the back of the box into the surrounding air 5 and Z0 represents the total impedance of the loudspeaker.
- the shunt impedances C1, C2, C3, C4, C5 represent the acoustic capacitances of the cavities between partitions and the series imped- 10 ances m1, m2, ma, m4, m5 represent the acoustic inertance of the orifices.
- the structure as illustrated in Fig. 2 is an acoustic low pass filter.
- Z i s0 the acoustic impedance of the cavities
- FIG. 3 the system is shown applied to a radio 7 cabinet.
- the structure and arrangement of the panels and orifices is the same as in Fig. 1-. It is possible to put part of the radio receiving apparatus in the cavities but if this is to bedone, the cavities should be designed so-that they will have the proper volume when the apparatus is included therein. If the cabinet be placed against 'a wall or if the orifices in the outer'panel l2e be closed making the back of the box or cabinet completely closed;1Z-is infinite and therewill be a gradual attenuation of low frequencies but there will be no peaks or regions of undueresponse.
- Acoustic apparatus comprising a loudspeaker including a diaphragm, a cabinet in which said loudspeaker is mounted, partitions in said cabinet; one of said partitions being arranged to form a chamber incommunication with the back of said diaphragm, the other partitions being arranged to form cavities with adjacent partitions, and a single orifice in each of said partitions' interconnecting said cavities, said orifices obstructed; the dimensions of said orificesand cavities being such that sound will be transmitted therethroughwithout attenuation. .i
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- Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Details Of Audible-Bandwidth Transducers (AREA)
- Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
Description
Oct. 26, 1937. H. F. OLSON ACOUSTIC APPARATUS Fild Dec. 20, 1934 \\\\\\\\\\\\\\\\\\\\\\\\\\kl\\\\\\\\\\\\\\\\\\\\\\\\\\\/ a a 7. 1/ 4/ MW M rw INVENTOR ATTORNEY Patented Oct. 26, 1937 UNIV-TED STATES.
ACOUSTIC APPARATUS Harry I. Olson, Collingswood, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application December .20, 1934, Serial No. 758,374 2 Claims. (oi. 181- 31) This invention relates to acoustic apparatus. More specifically it relates to apparatus for the elimination of cabinet resonance resulting from a loudspeaker or the like being enclosed in a 5; cabinet such as a radio cabinet.
The usual type of .box' enclosing the back of loudspeakers'coristitutes an acoustic impedance of such nature that the sign of the acoustic reactance at the loudspeaker changes from plus to minus or vice versa, as the sound being reproduced passes through certain frequencies. At these frequencies which are referred to as the natural resonant periods of the system, the acoustic output of the loudspeaker and associated system is considerably greater than at frequencies on either side of the resonant frequencies. This effect leads to non-uniform response over the frequency range and to a decrease in the fidelity of the system.
It is an object of the invention to improve the response over the frequency range of a loudspeaker by changing the type of acoustic impedance into which the back of the loudspeaker feeds. According to the invention the acoustic impedance into which the back of the loudspeaker feeds is made such that sound will be transmitted therethrough without attenuation. Other objects of the invention will become apparent upon reading the following specification and appended claims.
An approved form of the invention is illustrated in the accompanying drawing in which Fig. 1 illustrates diagrammatically an arrangement for the elimination of resonance frequencies in the box enclosing the back of a loudspeaker diaphragm; Fig. 2 is the electrical analog of the construction shown in Fig. 1, and Fig. 3 illustrates how the invention may be applied to a loudspeaker mounted in a radio cabinet.
In the modification illustrated by Fig. 1 the loudspeaker is mounted in a box which encloses the back of the diaphragm. For the purpose of convenience the driving mechanism has been omitted, but the diaphragm is illustrated at I0.
The box II which encloses the loudspeaker, contains a plurality of panels I2a, I22), I20, IZd, and He, arranged substantially parallel with the front wall 13 in which the diaphragm I0 is mounted. Each of the panels I20, I21), I20, IM and I26 contains an orifice Ma, Mb, I40, Md and Me. The panels are spaced from the wall 13 and from each other to form cavities C1, C2, C3, C4, C5. The orifices constitute acoustic inertance m1, m2, m3, m4 and ms. The cavities formed by the par- 65 tltions constitute acoustic impedances.
The operation of the apparatus illustrated in Fig. 1 can be determined by referring to the circuit of Fig. 2 which is the electrical analog of the apparatus of Fig. 1. In the electrical analog Z0 represents the'impedance of the opening in the back of the box into the surrounding air 5 and Z0 represents the total impedance of the loudspeaker. The shunt impedances C1, C2, C3, C4, C5 represent the acoustic capacitances of the cavities between partitions and the series imped- 10 ances m1, m2, ma, m4, m5 represent the acoustic inertance of the orifices. The structure as illustrated in Fig. 2, is an acoustic low pass filter.
The acoustic impedance of the orifices is given by equations 15 10.: Z1 -5 where l=density of air w=21rf c=conductivity of orifices 20 ,f=frequency and where R=radius of orifices l=length of orifices The acoustic impedance of the cavities is given by Z i s0 where A=velocity of sound V=volume of cavity the limiting values of no attenuation is determined It will be seen that it is possible to so choose the size of the orifices and cavities that sound will be transmitted through the back with no attenuation.
In this system there is no abrupt change in the acoustic impedance into which the back of the loudspeaker feeds and therefore the structure does not introduce irregularities in the response.
It may be desirable to locate the high fre- 5O quency cut off for the system within the region of response of the diaphragm. This should not cause any difficulty because at the higher frequencies the loudspeaker is very loosely coupled to the filter system. As the frequency increases any device enclosing a diaphragm has only a' slight effect upon the performance. That ls, the system enclosing the loudspeaker has the largest effect on the response at the lower frequencies.
' At low frequencies there is no abrupt change in the filter impedance and therefore there should be no discontinuities in the response of the loudspeaker due to the filterr system terminating the back of the speaker. V
V In Fig. 3 the system is shown applied to a radio 7 cabinet. The structure and arrangement of the panels and orifices is the same as in Fig. 1-. It is possible to put part of the radio receiving apparatus in the cavities but if this is to bedone, the cavities should be designed so-that they will have the proper volume when the apparatus is included therein. If the cabinet be placed against 'a wall or if the orifices in the outer'panel l2e be closed making the back of the box or cabinet completely closed;1Z-is infinite and therewill be a gradual attenuation of low frequencies but there will be no peaks or regions of undueresponse.
While I have shown and described an approved form of my invention it is to be understood that various modifications and changes may be made thereto withoutdeparting from the spirit of the invention and i therefore desire to be limited only by the scope of the appended claims.
I claim: Q
1; Acoustic apparatus comprising a loudspeaker including a diaphragm, a cabinet in which said loudspeaker is mounted, partitions in said cabinet; one of said partitions being arranged to form a chamber incommunication with the back of said diaphragm, the other partitions being arranged to form cavities with adjacent partitions, and a single orifice in each of said partitions' interconnecting said cavities, said orifices obstructed; the dimensions of said orificesand cavities being such that sound will be transmitted therethroughwithout attenuation. .i
r ""HARRYOLSONK
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US758374A US2097289A (en) | 1934-12-20 | 1934-12-20 | Acoustic apparatus |
DER95037D DE712170C (en) | 1934-12-20 | 1935-12-20 | Arrangement to avoid housing resonance in loudspeaker housings |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US758374A US2097289A (en) | 1934-12-20 | 1934-12-20 | Acoustic apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
US2097289A true US2097289A (en) | 1937-10-26 |
Family
ID=25051502
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US758374A Expired - Lifetime US2097289A (en) | 1934-12-20 | 1934-12-20 | Acoustic apparatus |
Country Status (2)
Country | Link |
---|---|
US (1) | US2097289A (en) |
DE (1) | DE712170C (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2541163A (en) * | 1946-09-27 | 1951-02-13 | Edison Inc Thomas A | Acoustically filtered phonographic reproducer |
US2627931A (en) * | 1949-12-03 | 1953-02-10 | Stromberg Carlson Co | Means for improving frequency response of sound systems |
US2656004A (en) * | 1947-04-29 | 1953-10-20 | Rca Corp | Multisection acoustic filter |
US2880817A (en) * | 1953-10-28 | 1959-04-07 | Pickard & Burns Inc | Loudspeaker system |
US2971597A (en) * | 1941-09-05 | 1961-02-14 | Henry Heinrich & Co | Electro-acoustic devices |
US3470976A (en) * | 1967-12-11 | 1969-10-07 | Procter Brevard | High fidelity speaker |
US4189627A (en) * | 1978-11-27 | 1980-02-19 | Bell Telephone Laboratories, Incorporated | Electroacoustic transducer filter assembly |
EP0062401A1 (en) * | 1981-04-02 | 1982-10-13 | Ronald Leslie Stephens Daniel | A loudspeaker cabinet |
DE19620010B4 (en) * | 1995-05-18 | 2012-02-23 | Bose Corp. | Speaker system with satellite housing |
-
1934
- 1934-12-20 US US758374A patent/US2097289A/en not_active Expired - Lifetime
-
1935
- 1935-12-20 DE DER95037D patent/DE712170C/en not_active Expired
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2971597A (en) * | 1941-09-05 | 1961-02-14 | Henry Heinrich & Co | Electro-acoustic devices |
US2541163A (en) * | 1946-09-27 | 1951-02-13 | Edison Inc Thomas A | Acoustically filtered phonographic reproducer |
US2656004A (en) * | 1947-04-29 | 1953-10-20 | Rca Corp | Multisection acoustic filter |
US2627931A (en) * | 1949-12-03 | 1953-02-10 | Stromberg Carlson Co | Means for improving frequency response of sound systems |
US2880817A (en) * | 1953-10-28 | 1959-04-07 | Pickard & Burns Inc | Loudspeaker system |
US3470976A (en) * | 1967-12-11 | 1969-10-07 | Procter Brevard | High fidelity speaker |
US4189627A (en) * | 1978-11-27 | 1980-02-19 | Bell Telephone Laboratories, Incorporated | Electroacoustic transducer filter assembly |
EP0062401A1 (en) * | 1981-04-02 | 1982-10-13 | Ronald Leslie Stephens Daniel | A loudspeaker cabinet |
DE19620010B4 (en) * | 1995-05-18 | 2012-02-23 | Bose Corp. | Speaker system with satellite housing |
Also Published As
Publication number | Publication date |
---|---|
DE712170C (en) | 1941-10-15 |
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