EP0072991A2 - Speaker system - Google Patents
Speaker system Download PDFInfo
- Publication number
- EP0072991A2 EP0072991A2 EP82107390A EP82107390A EP0072991A2 EP 0072991 A2 EP0072991 A2 EP 0072991A2 EP 82107390 A EP82107390 A EP 82107390A EP 82107390 A EP82107390 A EP 82107390A EP 0072991 A2 EP0072991 A2 EP 0072991A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- vibration plate
- type vibration
- cone type
- cone
- speaker
- 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.)
- Granted
Links
- 230000000694 effects Effects 0.000 claims abstract description 35
- 230000000295 complement effect Effects 0.000 claims abstract description 10
- 230000002093 peripheral effect Effects 0.000 claims description 9
- 239000000725 suspension Substances 0.000 description 13
- 230000003247 decreasing effect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000000994 depressogenic effect Effects 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000009545 invasion Effects 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
- H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
- H04R9/06—Loudspeakers
-
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
- H04R7/12—Non-planar diaphragms or cones
Definitions
- This invention relates to a speaker system, and more particularly to a speaker system using a cone type in which the dip effect of the cone is decreased.
- a buffle with an infinite size is suitable for the buffle surface of the cone type speaker.
- a buffle with a finite plane surface has been applied.
- cylindrical surface, spherical surface and other types are used.
- a depression in the cone surface causes a later-mentioned so-called "dip effect" in the voice pressure-frequency characteristic and the voice pressure phase-frequency characteristic. This disturbs reproduction with high fidelity.
- Fig. 1 the cross-section of a cone type speaker is shown to explain the "dip effect".
- 1 and 1' denote cone type vibration plates with semi-vertical angles a and ⁇ , respectively.
- the object of this invention is to eliminate the above-mentioned defect of the prior art and to provide a speaker system of cone type with the dip effect reduced.
- a part of the cone type vibration plate is made to protrude above the buffle surface, or in the direction of a space to which the sound wave is radiated from the vibration plate, so that the dip and bump effects appear simultaneously in the center and outer peripheral parts respectively.
- a dome type vibration plate with a bump effect is fixed to the cone type vibration plate so that the bump and dip effects appear in the center and outer peripheral parts respectively.
- the complementary characteristic for the dip and bump effects is not perfect.
- the frequency range of both the cone type and dome type vibration plates is limited in such a range where the plates may be assumed to be a point sound source on an infinite size buffle (ka ⁇ ⁇ 2)
- a fair complementary characteristic can be obtained under the following condition: the protruded and depressed parts of the vibration plate with respect to a plane containing the buffle surface have substantially the same volume.
- This invention makes use of the complementary characteristic in this region.
- Fig. 3 is the cross-sectional view of a dome type vibration plate for the explanation of the bump effect as applied by this invention.
- Fig. 4 is a diagram of the frequency characteristic of the dome type vibration plate shown in Fig. 3.
- a reference numeral 11 denotes a speaker, 12 a cone type vibration plate (hereinafter referred to as a cone simply) and 12' a flexible edge-suspension.
- the edge-suspension 12' may be of the same material as that of the cone 12, or of a different material therefrom. In the latter case, a part of the edge-suspension is adhered to the cone 12.
- 12" denotes a margin part of adhering the edge-suspension 12'.
- 13 denotes a center cap which is used to avoid the generation of noise due to invasion of dust and iron powder, etc. into the speaker 11.
- the center cap 13 is also useful to avoid the bending vibration of the cone type vibration plate 12 and is called as a dust cap.
- 14 denotes a frame, 14' a frame raising part, 15 a magnetic circuit, 16 a buffle plate, 16' a front surface of the buffle plate 16 (hereinafter referred to as a buffle surface simply), and 16" a virtual plane which contains the buffle surface 16' and crosses the speaker 11. Even when the buffle surface 16' is a curves surface, the surface to which the speaker 11 is fixed may be a plane.
- the virtual surface 16" divides a group of surfaces consisting of the front surface of the cone 12, the front surface of the edge-suspension 12' and the front surface of the center cap 13 into front and rear parts.
- the front part B contains the edge-suspension 12' while the rear part C contains the center cap 13.
- the center cap 13 is formed by either a mesh or an apertured plate, the volume expressed by a shade is decreased by a fraction corresponding to the apertured ratio.
- the height of the frame raising part 14' should be determined along this line.
- the existence of the above-mentioned volume has equivalently an effect that a part of the buffle surface 16' protrudes toward the edge-suspension 12' and the margin part 12". Therefore, the effect of protruding the group of surfaces above the virtual plane 16" is to some extent cancelled.
- the diameter of the frame raising part 14' is made infinitely large, not only the group of surfaces but also the buffle surface 16' protrude. This means that the group of surfaces do not protrude above the buffle surface 16' at all. In order to recover the cancelled part, the group of surfaces should be further protruded. If the frame 14 does not have such a frame raising part 14', an annular body similar to 14' may be separately formed and combined.
- Fig. 7 shows the second embodiment of a speaker system according to this invention and the cross-section of the peripheral part of it.
- a combination of a cone type vibration plate and a vibration plate with a concave surface, e.g. a dome type vibration plate the aforementioned object can be attained without protruding the frame 14 above the virtual plane 16".
- a speaker denotes a speaker, 21 a frame, and 22 a dome type vibration plate (hereinafter referred to as a dome simply).
- the dome 22 is fixed to the cone 12.
- a volume @ which consists of a surface part of the dome 22 below the virtual plane 16" and a surface part of the cone 12 that is not covered with the dome 12 and lies below the virtual plane 16".
- the volume E projected to a plane vertical to the virtual plane 16" is shown by a shade.
- a volume F which consists of a surface part of the dome above the virtual plane 16" and is shown by another shade.
- the mass of the dome 22 according to this method is liable to become large.
- the strength of the cone 12 should be considerably large. A drawback of this method, therefore, is that the mass of the cone becomes easily large.
- Fig. 8 is a diagram showing the third embodiment of a speaker system according to this invention and the cross-section of the peripheral part of it. In this embodiment, the methods of the first and second embodiments shown in Figs. 5 and 7 are commonly applied.
- a part of the cone type vibration plate 12 is protruded above the buffle surface 16' in the direction of a space to which the sound wave is radiated from the cone type vibration plate 12, thereby to obtain a dip effect.
- a vibration plate with a concave surface e.g. a dome type vibration plate 22
- the cone type vibration plate is combined with the cone type vibration plate, thereby to obtain a bump effect.
- this invention since the dip effect of a vibration plate can be decreased without using any planar vibration plate, sound pressure-frequency and sound pressure phase-frequency characteristics which can match those of a speaker system with use of a planar vibration plate can be obtained. Moreover, this invention has an effect of making the cost as low as or equal to that of a prior art speaker system using a cone type vibration plate.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Multimedia (AREA)
- Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
Abstract
Description
- This invention relates to a speaker system, and more particularly to a speaker system using a cone type in which the dip effect of the cone is decreased.
- In principle, a buffle with an infinite size is suitable for the buffle surface of the cone type speaker. Usually, however, a buffle with a finite plane surface has been applied. Occasionally, cylindrical surface, spherical surface and other types are used. As the cone surface is more depressed than the buffle surface, a depression in the cone surface causes a later-mentioned so-called "dip effect" in the voice pressure-frequency characteristic and the voice pressure phase-frequency characteristic. This disturbs reproduction with high fidelity.
- In Fig. 1, the cross-section of a cone type speaker is shown to explain the "dip effect". In this figure, 1 and 1' denote cone type vibration plates with semi-vertical angles a and β, respectively.
- Fig. 2 shows frequency characteristics (described in IECE of Japan Vol. 77 No. 128 KGEA 77-26, Oie et al) of the cone type speaker of Fig. 1 with different semi-vertical angles. It is assumed that
vibration plates 1 and 1' of cone type are making a piston-like vibration in the horizontal direction. Now, defining k as the wave number (k = 2 π/λ, λ is wave length), a as the actual working radius of the vibration plate and c as the sound speed, it can be seen in Fig. 2 that for a deeper cone and a smaller semi-vertical angle the bump at ka = 1 - 2 becomes larger while the dip at ka = 3 - 4 becomes smaller. - Recently, a plane speaker has been used in order to suppress such a dip effect. However, the plane type speaker has usually a heavier vibration plate and hence the electric-acoustic conversion efficiency is worse than that of cone type. If the magnetic energy is increased in order to enhance this efficiency, the cost required therefor could be above that of the vibration plate itself. This will raise the cost of the speaker. This has been the above-mentioned drawback of the plane speaker.
- The object of this invention is to eliminate the above-mentioned defect of the prior art and to provide a speaker system of cone type with the dip effect reduced. In order to attain this object, according to this invention, a part of the cone type vibration plate is made to protrude above the buffle surface, or in the direction of a space to which the sound wave is radiated from the vibration plate, so that the dip and bump effects appear simultaneously in the center and outer peripheral parts respectively. Alternatively, a dome type vibration plate with a bump effect is fixed to the cone type vibration plate so that the bump and dip effects appear in the center and outer peripheral parts respectively. With use of such a cone type speaker with a complementary characteristic for dip and bump effects, this invention realizes voice pressure-frequency and voice pressure phase-frequency characteristics which are similar to those of a plane type speaker.
- It is needless to say that the complementary characteristic for the dip and bump effects is not perfect. However, if the frequency range of both the cone type and dome type vibration plates is limited in such a range where the plates may be assumed to be a point sound source on an infinite size buffle (ka < √2), a fair complementary characteristic can be obtained under the following condition: the protruded and depressed parts of the vibration plate with respect to a plane containing the buffle surface have substantially the same volume. This invention makes use of the complementary characteristic in this region.
- Preferred embodiments of this invention will be described hereinafter in conjunction with the accompanying drawings, in which:
- Fig. 1 is the cross-sectional view of a cone type speaker for the explanation of the dip effect.
- Fig. 2 is a graph showing the frequency characteristic of the cone type speaker of Fig. 1 for different semi-vertical angles.
- Fig. 3 is the cross-sectional view of a dome type vibration plate for the explanation of the bump . effect as applied by this invention.
- Fig. 4 is a diagram of the frequency characteristic of the dome type vibration plate (refer to "Acoustic Vibration Theory" Hayasaka et al published by Maruzen in 1974) shown in Fig. 3.
- Fig. 5 is the cross-sectional view showing a first embodiment of the speaker system according to this invention.
- Fig. 6 is a planar view of Fig. 5.
- Fig. 7 is the cross-sectional view showing a second embodiment of the speaker system according to this invention.
- Fig. 8 is the cross-sectional view showing a third embodiment of the speaker system according to this invention.
- Embodiments of the speaker system of this invention will be explained hereinafter with reference to the drawings.
- Fig. 3 is the cross-sectional view of a dome type vibration plate for the explanation of the bump effect as applied by this invention.
- Fig. 4 is a diagram of the frequency characteristic of the dome type vibration plate shown in Fig. 3.
- In Fig. 3, according as the distance H is decreased from R of a semi-sphere ⓓ to © , ⓑ and ⓐ, the fractional variation D of the velocity potential against ka varies due to the bump effect, as shown in Fig. 4. It is seen further that as the distance H increases from @ to @ in Fig. 3 the dip in the frequency characteristic at ka = 1 - 2 increases. According to this invention, another vibration plate having a bump effect is fixed to a cone type vibration plate having a dip effect as mentioned above. Through utilization of a complementary characteristic for the dip and bump effects, the invention obtains a characteristic similar to that of a plane speaker.
- In Fig. 5 showing the first embodiment of the speaker system according to this invention and the cross-section of the peripheral portions thereof, a reference numeral 11 denotes a speaker, 12 a cone type vibration plate (hereinafter referred to as a cone simply) and 12' a flexible edge-suspension. The edge-suspension 12' may be of the same material as that of the
cone 12, or of a different material therefrom. In the latter case, a part of the edge-suspension is adhered to thecone 12. 12" denotes a margin part of adhering the edge-suspension 12'. 13 denotes a center cap which is used to avoid the generation of noise due to invasion of dust and iron powder, etc. into the speaker 11. Thecenter cap 13 is also useful to avoid the bending vibration of the conetype vibration plate 12 and is called as a dust cap. 14 denotes a frame, 14' a frame raising part, 15 a magnetic circuit, 16 a buffle plate, 16' a front surface of the buffle plate 16 (hereinafter referred to as a buffle surface simply), and 16" a virtual plane which contains the buffle surface 16' and crosses the speaker 11. Even when the buffle surface 16' is a curves surface, the surface to which the speaker 11 is fixed may be a plane. Thevirtual surface 16" divides a group of surfaces consisting of the front surface of thecone 12, the front surface of the edge-suspension 12' and the front surface of thecenter cap 13 into front and rear parts. The front part B contains the edge-suspension 12' while the rear part C contains thecenter cap 13. - Now, let us consider the band width where the
cone 12 performs such a piston vibration as shown by an arrow A of Fig. 5. The inner periphery of the edge-suspension 12' moves with thecone 12, but the outer periphery thereof is fixed to theframe 14. The effective radius a of the edge-suspension 12' in this case is obtained by the following equation (1)cone 12 and a2 is the radius of the outermost part of the edge-suspension which stands still. In another word, it may be assumed that the peripheral region with a radius a is making a piston vibration and that the outer part is standing still. We call the surface of the region Ⓓ with a piston vibration as an equivalent piston vibration surface. - Now, consider a front part of the equivalent piston vibration surface @ above the
virtual plane 16", and define ashaded area 17 formed by projecting the front part of the equivalent piston vibration surface onto a plane vertical to thevirtual plane 16". Next, consider a rear part of the equivalent piston vibration surface @ below thevirtual plane 16", and define ashaded area 18 formed by projecting the rear part of the equivalent piston vibration surface onto a plane vertical to thevirtual plane 16". If nocenter cap 13 is formed, the shaded part inside thebobbin 19 in Fig. 5 disappears. Hence, the shaded volume below thevirtual plane 16" is decreased by a corresponding fraction. Furthermore, when thecenter cap 13 is formed by either a mesh or an apertured plate, the volume expressed by a shade is decreased by a fraction corresponding to the apertured ratio. In any case, it is preferable to determine the position of thevirtical plane 16" with respect to the equivalent piston vibration surface in such a manner that the above-mentionedvolumes cylindrical surface 20 which lies on the periphery of the edge-suspension 12' with a radius a vertically to thevirtual plane 16", a surface part of the edge-suspension 12' lying outside the virtualcylindrical surface 20, the surface of themargin part 12", the outer surface of the frame raising part 14' and thevirtual surface 16". The reason is as follows. The existence of the above-mentioned volume has equivalently an effect that a part of the buffle surface 16' protrudes toward the edge-suspension 12' and themargin part 12". Therefore, the effect of protruding the group of surfaces above thevirtual plane 16" is to some extent cancelled. If the diameter of the frame raising part 14' is made infinitely large, not only the group of surfaces but also the buffle surface 16' protrude. This means that the group of surfaces do not protrude above the buffle surface 16' at all. In order to recover the cancelled part, the group of surfaces should be further protruded. If theframe 14 does not have such a frame raising part 14', an annular body similar to 14' may be separately formed and combined. - Fig. 7 shows the second embodiment of a speaker system according to this invention and the cross-section of the peripheral part of it. In this figure, by a combination of a cone type vibration plate and a vibration plate with a concave surface, e.g. a dome type vibration plate, the aforementioned object can be attained without protruding the
frame 14 above thevirtual plane 16". - In Fig. 7, 11' denotes a speaker, 21 a frame, and 22 a dome type vibration plate (hereinafter referred to as a dome simply). The
dome 22 is fixed to thecone 12. Define a volume @ which consists of a surface part of thedome 22 below thevirtual plane 16" and a surface part of thecone 12 that is not covered with thedome 12 and lies below thevirtual plane 16". The volume Ⓔ projected to a plane vertical to thevirtual plane 16" is shown by a shade. Further, define a volume Ⓕ which consists of a surface part of the dome above thevirtual plane 16" and is shown by another shade. If the size and the shape of thedome 22 are determined in such a manner that the volumes Ⓔ and Ⓕ become substantially equal to each other, the afore-mentioned object can be attained without protruding theframe 21 above thevirtual plane 16". However, the mass of thedome 22 according to this method is liable to become large. Moreover, in order to support thedome 22, the strength of thecone 12 should be considerably large. A drawback of this method, therefore, is that the mass of the cone becomes easily large. - Fig. 8 is a diagram showing the third embodiment of a speaker system according to this invention and the cross-section of the peripheral part of it. In this embodiment, the methods of the first and second embodiments shown in Figs. 5 and 7 are commonly applied.
- In Fig. 8 as in Fig. 5, a part of the cone
type vibration plate 12 is protruded above the buffle surface 16' in the direction of a space to which the sound wave is radiated from the conetype vibration plate 12, thereby to obtain a dip effect. At the same time, as in Fig. 7, a vibration plate with a concave surface, e.g. a dometype vibration plate 22, is combined with the cone type vibration plate, thereby to obtain a bump effect. As a result, in Fig. 8, a complementary characteristic of dip and bump effects is attained by setting - As described above, according to this invention, since the dip effect of a vibration plate can be decreased without using any planar vibration plate, sound pressure-frequency and sound pressure phase-frequency characteristics which can match those of a speaker system with use of a planar vibration plate can be obtained. Moreover, this invention has an effect of making the cost as low as or equal to that of a prior art speaker system using a cone type vibration plate.
Claims (4)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13409681A JPS5838097A (en) | 1981-08-28 | 1981-08-28 | Loudspeaker system |
JP134096/81 | 1981-08-28 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0072991A2 true EP0072991A2 (en) | 1983-03-02 |
EP0072991A3 EP0072991A3 (en) | 1983-04-20 |
EP0072991B1 EP0072991B1 (en) | 1985-07-03 |
Family
ID=15120337
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19820107390 Expired EP0072991B1 (en) | 1981-08-28 | 1982-08-13 | Speaker system |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0072991B1 (en) |
JP (1) | JPS5838097A (en) |
DE (1) | DE3264559D1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1989004581A1 (en) * | 1987-11-12 | 1989-05-18 | Robert Michael Grunberg | Electro-acoustic transducers |
WO1999025149A2 (en) * | 1997-11-06 | 1999-05-20 | Macklaine Di Francesco Di Summa E C. S.N.C. | Moving-coil loudspeaker |
DE102005023759B3 (en) * | 2005-05-19 | 2006-09-14 | Florat Seta | Acoustic transducer with full cone membrane for loud speaker cabinet |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR673659A (en) * | 1928-08-13 | 1930-01-17 | Sound reproducer | |
US2303989A (en) * | 1941-03-01 | 1942-12-01 | Rca Corp | Signal translating apparatus |
US2549091A (en) * | 1946-10-25 | 1951-04-17 | Bell Telephone Labor Inc | Diaphragm for electroacoustic transducers |
DE899048C (en) * | 1950-05-04 | 1953-12-07 | Adelbert Stephan | Loudspeaker with tilt-free multi-cone membrane |
US3746125A (en) * | 1971-09-10 | 1973-07-17 | Lowell Mfg Co | Protective speaker back-can |
US3940576A (en) * | 1974-03-19 | 1976-02-24 | Schultz Herbert J | Loudspeaker having sound funnelling element |
US4057694A (en) * | 1975-10-23 | 1977-11-08 | Pioneer Electronic Corporation | Speaker diaphragm having flat response curve |
US4146756A (en) * | 1977-01-28 | 1979-03-27 | Hitachi, Ltd. | Moving voice coil transducer with diaphragm having concentric sections of opposite curvature |
-
1981
- 1981-08-28 JP JP13409681A patent/JPS5838097A/en active Pending
-
1982
- 1982-08-13 DE DE8282107390T patent/DE3264559D1/en not_active Expired
- 1982-08-13 EP EP19820107390 patent/EP0072991B1/en not_active Expired
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR673659A (en) * | 1928-08-13 | 1930-01-17 | Sound reproducer | |
US2303989A (en) * | 1941-03-01 | 1942-12-01 | Rca Corp | Signal translating apparatus |
US2549091A (en) * | 1946-10-25 | 1951-04-17 | Bell Telephone Labor Inc | Diaphragm for electroacoustic transducers |
DE899048C (en) * | 1950-05-04 | 1953-12-07 | Adelbert Stephan | Loudspeaker with tilt-free multi-cone membrane |
US3746125A (en) * | 1971-09-10 | 1973-07-17 | Lowell Mfg Co | Protective speaker back-can |
US3940576A (en) * | 1974-03-19 | 1976-02-24 | Schultz Herbert J | Loudspeaker having sound funnelling element |
US4057694A (en) * | 1975-10-23 | 1977-11-08 | Pioneer Electronic Corporation | Speaker diaphragm having flat response curve |
US4146756A (en) * | 1977-01-28 | 1979-03-27 | Hitachi, Ltd. | Moving voice coil transducer with diaphragm having concentric sections of opposite curvature |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1989004581A1 (en) * | 1987-11-12 | 1989-05-18 | Robert Michael Grunberg | Electro-acoustic transducers |
WO1999025149A2 (en) * | 1997-11-06 | 1999-05-20 | Macklaine Di Francesco Di Summa E C. S.N.C. | Moving-coil loudspeaker |
WO1999025149A3 (en) * | 1997-11-06 | 1999-07-22 | Macklaine Di Francesco Di Summ | Moving-coil loudspeaker |
DE102005023759B3 (en) * | 2005-05-19 | 2006-09-14 | Florat Seta | Acoustic transducer with full cone membrane for loud speaker cabinet |
Also Published As
Publication number | Publication date |
---|---|
JPS5838097A (en) | 1983-03-05 |
DE3264559D1 (en) | 1985-08-08 |
EP0072991B1 (en) | 1985-07-03 |
EP0072991A3 (en) | 1983-04-20 |
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