WO1991016798A1 - Systeme a transducteurs audio - Google Patents

Systeme a transducteurs audio Download PDF

Info

Publication number
WO1991016798A1
WO1991016798A1 PCT/US1991/002481 US9102481W WO9116798A1 WO 1991016798 A1 WO1991016798 A1 WO 1991016798A1 US 9102481 W US9102481 W US 9102481W WO 9116798 A1 WO9116798 A1 WO 9116798A1
Authority
WO
WIPO (PCT)
Prior art keywords
audio
audio transducer
transducers
diaphragms
transducer system
Prior art date
Application number
PCT/US1991/002481
Other languages
English (en)
Inventor
Paul W. Paddock
Steven R. Geist
Original Assignee
Linaeum Corporation
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Linaeum Corporation filed Critical Linaeum Corporation
Publication of WO1991016798A1 publication Critical patent/WO1991016798A1/fr

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
    • 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 
    • H04R1/227—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only  using transducers reproducing the same frequency band
    • 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
    • H04R1/2869—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself
    • H04R1/2876—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of damping material, e.g. as cladding
    • H04R1/288—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of damping material, e.g. as cladding for loudspeaker transducers

Definitions

  • This invention generally relates to an audio transducer system. More particularly, the invention relates to an audio transducer system having plural audio transducers which cooperate with one another.
  • audio transducers as exemplified by audio loudspeakers, are known in the prior art.
  • One common form of audio transducer comprises a cone shaped diaphragm with an attached electromagnetic motor driving element.
  • the cone diaphragm is mounted to a frame by a flexible expanse which bounds the perimeter of the cone.
  • a wire coil located within a magnetic field responds to alternating current impulses generated by a signal source or amplifier, thereby causing the diaphragm to vibrate.
  • This type of transducer is generally characterized by a relatively high diaphragm and coil mass, which creates high inertial forces in the diaphragm. This characteristic is most pronounced in woofer or subwoofer type transducers which are designed to provide lower frequency responses.
  • the audio transducer is mounted in a loud speaker cabinet.
  • any movement or vibration of the cabinet represents lost energy which is unavailable to generate sound waves and therefore decreases the efficiency of the transducer.
  • the movement or vibration of the cabinet is transferred to the floor or other cabinet support surface, thereby causing the floor to act as a secondary membrane radiator which produces destructive interference effects through sound wave reinforcements and cancellations at various points within the room.
  • the foregoing problems are most acute in woofers and subwoofers having relatively large and heavy diaphragms. Consequently, the cabinets used to mount woofers and subwoofers tend to be bulky, heavy and relatively inefficient.
  • An object of this invention is to provide an improved audio transducer system which overcomes the above limitations and disadvantages.
  • an object of the invention is to provide an audio transducer system of improved efficiency.
  • Another object of the invention is to provide a transducer system which reduces deleterious cabinet vibration and movement caused by vibration of the diaphragm.
  • Still another object of the invention is to provide an acoustically and physically balanced transducer system.
  • a further object of the invention is to provide a transducer system which provides excellent low bass performance and yet is relatively compact, light in weight and highly efficient.
  • an improved audio transducer system includes a first audio transducer having a first diaphragm, and a second audio transducer having a second diaphragm.
  • the first and second audio transducers are supported by respective cabinets which are rigidly interconnected such that the first and second diaphragms are disposed in proximate, spaced apart, face-to-face relationship.
  • the performance of the transducers is further improved by electrical coupling means for coupling the first and second audio transducers so that they are operated in phase electrically with one another.
  • Other improvements relate to the characteristics of the transducers, the spacing between the two transducers, damping devices, cabinet construction, and construction for mounting the two transducers and their respective cabinets to one another to form a common unit.
  • Fig. 1 is a partially sectional view of a conventional cone-type audio transducer.
  • Fig. 2 is a perspective view of the present invention.
  • Fig. 3 is a vertical sectional view of the present invention.
  • Fig. 4 is an electrical schematic in accordance with the present invention.
  • Fig. 5 is a partial vertical sectional view of a second embodiment of the present invention.
  • an audio transducer system includes a pair of identical audio transducers 10a, 10b which are fixedly coupled together as a common unit so as to provide a symmetrical and balanced system in which the transducers are electrically and mechanically in phase with one another.
  • Audio transducers 10a, 10b are mirror images of one another and have respective sound producing diaphragms 14a, 14b and electromagnetic driving elements 20a, 20b.
  • Transducers 10a, 10b are conventional cone-style transducers of the type shown in Fig. 1, which has a cone- shaped diaphragm 14.
  • the present invention also includes cabinet means for supporting audio transducers 10a, 10b in an acoustic suspension manner and electrical coupling means for coupling transducers 10a, 10b in electrically in phase relationship.
  • Transducer positioning means are provided to fixedly position transducers 10a, 10b with respect to one another such that the audio transducers and their respective diaphragms 14a, 14b are disposed in axially aligned, spaced apart, face-to-face relationship with an air space therebetween.
  • a signal source means such as an amplifier 18, is provided to generate alternating current impulses proportional to audio signals, which impulses shift polarity between 20 and 20,000 times per second.
  • the electrical coupling means supplies the current impulses generated by amplifier 18 to transducers 10a, 10b.
  • audio transducers 10a, 10b are identical high mass, high compliance audio transducers designed to provide a low resonant frequency in a cabinet means of desired volume.
  • the transducers have good extended low bass performance, a diaphragm diameter of 8 inches, and a maximum excursion limit of 0.75 inch.
  • audio transducers 10a, 10b preferably are identical so that they have the same acoustic and physical characteristics, and are true mirror images of one another.
  • transducers 10a and 10b have the same mass, shape, size and maximum excursion.
  • Transducers 10a, 10b are supported by respective cabinets or enclosures 22a, 22b.
  • Each cabinet 22a, 22b each have an identical construction and form part of the cabinet means.
  • Each cabinet 22a, 22b includes a cylindrical member 26 which is constructed from a thirty- four inch long section of polyvinyl chloride (PVC) pipe having a diameter of eight inches and a wall thickness of 1/4 inch.
  • the cabinet has a volume of 1600 cubic inches.
  • the rigidity of the PVC material and cylindrical construction serve to minimize wasted energy, undesirable distortions and extraneous frequency responses caused by cabinet walls which otherwise might flex and vibrate. It will be appreciated that other known cabinet configurations and materials which limit cabinet wall flexure and attendant acoustic loss also will work well.
  • transducers 10a, 10b could easily be mounted in a square cabinet. Each transducer and cabinet combination serves a loud speaker.
  • Each cylindrical member 26 has a diameter comparable to that of the audio transducer and therefore is suited to receive and mount one of the audio transducers at one end thereof.
  • An internal annular shoulder 30 is provided at such end to seat the audio transducer which is fixedly, but removably mounted in place by fastening screws 34 threaded into either shoulder 30 or an end face of member 26.
  • the opposite end of member 26 is sealed by an end cap or plug 38, which is glued in place to provide an air-tight seal.
  • cylindrical member 26 is sealed at one end by plug 38 and at its opposite end by audio transducer 10a or 10b, with an internal cavity or chamber defined therebetween.
  • the audio transducer is supported in an acoustic-suspension manner whereby movement of the diaphragm causes the air in the internal cavity to compress or rarify, depending upon whether the movement of the diaphragm is toward or away from plug 38.
  • the air inside the sealed cabinet acts as a mechanical or acoustic spring to facilitate piston-like, back-and-forth motion of the diaphragm, with minimal distortion or undesirable flexing of the diaphragm.
  • Such acoustic suspension is particularly desirable in the case of woofers and subwoofers for which the present invention is particularly well suited, since woofers and subwoofers typically have compliant diaphragms designed for maximum excursion but prone to extraneous distortion and flexing.
  • a chamber damping means is provided within the internal cavity of each cabinet 22a, 22b to dampen any standing wave reflection which otherwise might be encountered in a long, narrow cabinet enclosure.
  • the damping means includes sections of fiberglass building insulation 40 (R16 or 19) , which are loosely packed in layers to completely fill the cabinet's internal cavity.
  • a screen 41 separates fiberglass insulation 40 from the audio transducer.
  • Other known damping materials such as polyester fluff, felt, long fiber wool and acoustic foam, and known methods for damping standing waves also will work well.
  • the transducer positioning means preferably includes a plurality of rigid column-like support members or spacer bars 42, which rigidly mount and interconnect cabinet 22a to cabinet 22b such that diaphragm 14a and diaphragm 14b are disposed in proximate spaced-apart, axially-aligned, face-to-face relationship with respect to each other.
  • Four support members 42 are equally spaced around the central circumference of the stacked transducer arrangement.
  • Each support member 42 is fastened at one end by suitable fastening means 44a to cabinet 22a and at its opposite end by suitable fastening means 44b to cabinet 22b.
  • Support members 42 are made of metal or comparable material to provide a rigid interconnection between cabinets 22a and 22b, and have sufficient strength to support the upper cabinet when disposed in an upright "stacked" position on a floor F (Fig. 3) .
  • the support members are sufficiently thin to provide a spacious, largely unobstructed central air space between the pair of face-to-face audio transducers, thereby permitting sound waves emanating from such central air space to travel unencumbered radially outwardly in a 360 degree arc.
  • diaphragm 14a to diaphragm 14b is important. It is preferable to make the spacing between the two diaphragms as close as possible, leaving just enough room to allow for maximum diaphragm excursion. For example, in the case of transducers having a maximum excursion limit of 0.75 inch, the optimum spacing between the diaphragms is approximately equal to the sum of the maximum excursions of each diaphragm, or about 1-1/2 inches. As so spaced, in normal operation diaphragms 14a and 14b will rarely, if ever, contact one another. The closest feasible spacing optimizes the operating efficiency of the system at the lowest frequencies in the range of about 20 to 30 Hertz.
  • improved efficiency also can be attained at greater spacings which preferably are no greater than the maximum transverse dimension (i.e., diameter) of the diaphragms.
  • the maximum spacing necessary for at least some level of improved efficiency is believed to be no greater than about 8 inches.
  • the preferred range of spacings available to improve the efficiency of tandem face-to-face transducers having various parameters and properties can be readily determined empirically by experimentation.
  • the advantages associated with a mechanically balanced system can be obtained regardless of the spacing between the diaphragms.
  • the electrical coupling means preferably includes a common electrical circuit 50 having leads 51a, 51b, in which audio transducers 10a, 10b are coupled together to operate in electrical parallel with amplifier 18.
  • the audio transducers are in phase electrically and, therefore, simultaneously receive the same alternating current impulses generated by amplifier 18.
  • a central damping means is provided between diaphragms 14a and 14b to dampen extraneous frequency responses, especially higher frequency irregularities, caused by sound waves bouncing between the diaphragms.
  • the central damping means preferably includes a damping disc 46 made of high-density fiberglass (preferably about 6 to 8 pounds per cubic foot), felt, or other suitable material. Damping disc 46 is supported by wires 52 or other suitable fastening means attached at one end to disc 46 and at their other end to respective support members 42.
  • a damping disc 46 having a thickness of about one-half to one inch and a diameter of about 3 inches works well when positioned centrally between 8-inch cone-style woofers to absorb energy in the upper frequency regions above the useful range of the woofers.
  • disc 46 can have various sizes and shapes depending upon the acoustic properties of the material. Disc 46 does not interfere with the vibrating motion of diaphragms 14a, 14b because it is axially aligned with recessed portions of the diaphragms where the spacing or gap between the diaphragms is relatively large.
  • the present invention provides a balanced self-actively loaded, dual transducer system in which both transducers are in phase electrically and mechanically, and operate in mirror image fashion.
  • diaphragms 14a, 14b move simultaneously either toward or away from each other.
  • the diaphragms travel toward and away from each other the same amount with respect to a neutral "at rest" reference base line.
  • the dual transducer system provides a near- perfect mechanical balance which virtually eliminates deleterious cabinet movement and vibration.
  • One diaphragm's electromagnetically-induced inertia causes forces to be exerted on its supporting cabinet.
  • such forces are offset by equal and opposite in phase forces resulting from the second diaphragms's electromagnetically-induced inertia.
  • These offsetting forces virtually eliminate cabinet movement and vibration and the attendant energy loss accompanying same, thereby significantly improving the over all efficiency of the system.
  • the problematic tendency of a single unbalanced transducer to excite the floor or other cabinet support surface into a secondary membrane radiator is greatly reduced, thereby virtually eliminating the resultant destructive interference effects particularly common in conventional subwoofer and woofer systems.
  • the present system greatly reduces energy loss, destructive harmonic distortions and peaks and valleys in the response curve caused by cabinet movement and vibration or flexing of the cabinet walls. It will be apparent that a rigid connection between the opposed transducers and their cabinets is necessary to permit the forces generated by the two diaphragms to counteract and offset one another. It will also be apparent that the foregoing advantages of a mechanically balanced system are not dependent upon the spacing of the two diaphragms, but rather on a physical arrangement of the diaphragms which is mechanically balanced. Thus, for example, a pair of face-to-face loud speakers separated by one to two feet or more can still be mechanically balanced.
  • the present system is particularly well-suited for use in subwoofers and woofers having relatively high diaphragm/coil mass and, hence, high inertial forces.
  • the illustrated embodiment described herein is designed for use as a subwoofer primarily in the frequency range of 20 to 120 Hertz. Woofers and subwoofers are particularly susceptible to the problems overcome by the present invention, as evidenced by the common personal experience of feeling the floor vibrate when a woofer or subwoofer is operated at a moderate to loud volume.
  • the present system works best for frequencies below about 400 to 500 Hertz, depending upon the size of the diaphragm, because the diaphragm behaves as a point source for large sound waves. Ideally, the diameter of the diaphragm should exceed the wave length of the highest frequency produced by a factor of about two. At higher frequencies the diaphragm no longer functions as a point source, causing phase cancellations and aberrations in the response curve.
  • the present system produces a net gain in efficiency of about 2 to 3 decibels when compared to a pair of identical audio transducers arranged in a different physical relationship. Such gain equates to a two-fold increase in efficiency. Some of the efficiency gain undoubtedly is attributable to the virtual elimination of extraneous cabinet motion and vibration. However, it is believed that the in phase operation of face-to-face diaphragms in close proximity to one another causes the air space therebetween to rarify and compress, depending upon whether the diaphragms are moving away from or toward one another, thereby causing the diaphragm pair to behave in combination as a larger diaphragm of greater surface area.
  • the air space between the two diaphragms is excited enough to cause a more efficient coupling of acoustic power falling somewhere between conventional baffle loading and horn loading. It is possible that the two audio transducers load each other acoustically. It is also possible that the compression/rarefication effect creates a ring of excited air surrounding such air space which behaves like a large diaphragm. This would explain the present invention's ability to pressurize a very large area relative to the relative small size of the transducer diaphragms.
  • the rarefication and compression effect is expected to drop off to the point where normal efficiency is reached once the spacing between the diaphragms roughly corresponds to the magnitude of the diaphragm diameter (the benefits of reduced cabinet motion aside) .
  • the rarefication and compression effect will drop off at a spacing of about 8 inches for cone style diaphragms having a maximum transverse dimension or diameter of 8 inches.
  • the present audio transducer system is particularly well suited to stand upright, it retains its inherent mechanical and acoustic balance regardless of its orientation.
  • cone-style diaphragms commonly used in woofers and subwoofers tend to settle somewhat because of their large mass.
  • the present audio transducer system with its symmetry in all three directions, can be periodically flipped upside down to counteract any such settling of the diaphragm. It will be apparent that the present audio transducer is suited for more than just loud speaker applications including, for example, microphone applications.

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)

Abstract

Un système à deux transducteurs audio comprend une paire de transducteurs audio identiques (10a, 10b) comportant chacun un diaphragme de type conique. Chaque transducteur est monté en suspension acoustique à une extrémité d'une enceinte cylindrique (26), laquelle est obturée à son extrémité opposée. Les enceintes sont montées fixes l'une par rapport à l'autre par des éléments de support en forme de colonne (42) de manière que les deux diaphragmes sont disposés à proximité adjacente, alignés axialement, espacés et face-à-face. Les deux transducteurs sont couplés ensemble en parallèle dans un circuit électrique commun de manière qu'ils sont électriquement en phase mutuellement. Cet agencement élimine les mouvements et les vibrations indésirables dus à des forces inertielles exercées dans une enceinte.
PCT/US1991/002481 1990-04-25 1991-04-11 Systeme a transducteurs audio WO1991016798A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US51429890A 1990-04-25 1990-04-25
US514,298 1990-04-25

Publications (1)

Publication Number Publication Date
WO1991016798A1 true WO1991016798A1 (fr) 1991-10-31

Family

ID=24046605

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1991/002481 WO1991016798A1 (fr) 1990-04-25 1991-04-11 Systeme a transducteurs audio

Country Status (2)

Country Link
AU (1) AU7771591A (fr)
WO (1) WO1991016798A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2258365A (en) * 1991-07-09 1993-02-03 Sohn Tong Hoon Speaker system with opposed drive units
WO1994004008A1 (fr) * 1990-04-27 1994-02-17 Wolf Daniel T Generateur d'ondes soniques
US5850460A (en) * 1994-09-01 1998-12-15 Matsushita Electric Industrial Co., Ltd. Bass speaker
WO2007081671A3 (fr) * 2006-01-03 2008-05-22 Iroquois Holding Company Système de haut-parleurs hébergés sphériquement avec équilibrage de force
WO2009039852A1 (fr) * 2007-09-28 2009-04-02 Lennart Jarde Système d'émission sonore isobare
NL1040501C2 (en) * 2013-11-15 2015-05-19 Qsources Bvba Device for creating a sound source.
FR3119960A1 (fr) 2021-02-18 2022-08-19 Moca Audio Véhicule comportant un dispositif de restitution sonore disposé dans un espace médian avant de l’habitacle, dispositif adapté

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4268719A (en) * 1977-06-04 1981-05-19 Manger J W Loudspeaker arrangements
US4327257A (en) * 1979-09-10 1982-04-27 Schwartz Leslie H Alignment device for electro-acoustical transducers
US4590333A (en) * 1984-06-14 1986-05-20 John Strohbeen Multidriver loudspeaker
US4783820A (en) * 1985-01-03 1988-11-08 Lyngdorf Johan P Loudspeaker unit
US4897877A (en) * 1987-05-18 1990-01-30 Oxford Speaker Company Sub-woofer driver combination with dual voice coil arrangement

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4268719A (en) * 1977-06-04 1981-05-19 Manger J W Loudspeaker arrangements
US4327257A (en) * 1979-09-10 1982-04-27 Schwartz Leslie H Alignment device for electro-acoustical transducers
US4590333A (en) * 1984-06-14 1986-05-20 John Strohbeen Multidriver loudspeaker
US4783820A (en) * 1985-01-03 1988-11-08 Lyngdorf Johan P Loudspeaker unit
US4897877A (en) * 1987-05-18 1990-01-30 Oxford Speaker Company Sub-woofer driver combination with dual voice coil arrangement

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994004008A1 (fr) * 1990-04-27 1994-02-17 Wolf Daniel T Generateur d'ondes soniques
GB2258365A (en) * 1991-07-09 1993-02-03 Sohn Tong Hoon Speaker system with opposed drive units
GB2258365B (en) * 1991-07-09 1995-05-10 Sohn Tong Hoon Speaker system with reproduced sound wave manipulation
US5850460A (en) * 1994-09-01 1998-12-15 Matsushita Electric Industrial Co., Ltd. Bass speaker
US8422713B2 (en) * 2006-01-03 2013-04-16 J. Craig Oxford Spherically housed loudspeaker system
US7796775B2 (en) * 2006-01-03 2010-09-14 Oxford J Craig Spherically housed loudspeaker system
US20110096947A1 (en) * 2006-01-03 2011-04-28 Oxford J Craig Spherically housed loudspeaker system
WO2007081671A3 (fr) * 2006-01-03 2008-05-22 Iroquois Holding Company Système de haut-parleurs hébergés sphériquement avec équilibrage de force
US20130301855A1 (en) * 2006-01-03 2013-11-14 J. Craig Oxford Spherically housed loudspeaker system
US9584904B2 (en) * 2006-01-03 2017-02-28 J. Craig Oxford Spherically housed loudspeaker system
WO2009039852A1 (fr) * 2007-09-28 2009-04-02 Lennart Jarde Système d'émission sonore isobare
NL1040501C2 (en) * 2013-11-15 2015-05-19 Qsources Bvba Device for creating a sound source.
WO2015071742A3 (fr) * 2013-11-15 2016-03-03 Qsources Bvba Dispositif permettant de créer une source sonore
US9936287B2 (en) 2013-11-15 2018-04-03 Rsonance B.V. Device for creating a sound source
FR3119960A1 (fr) 2021-02-18 2022-08-19 Moca Audio Véhicule comportant un dispositif de restitution sonore disposé dans un espace médian avant de l’habitacle, dispositif adapté
WO2022175328A1 (fr) 2021-02-18 2022-08-25 Moca Audio Console centrale avant de véhicule avec haut-parleurs, et véhicule la comportant

Also Published As

Publication number Publication date
AU7771591A (en) 1991-11-11

Similar Documents

Publication Publication Date Title
US5710395A (en) Helmholtz resonator loudspeaker
JP2673002B2 (ja) スピーカシステム
US9060219B2 (en) Loudspeakers and systems
AU2003217250B2 (en) Low profile audio speaker
US6460651B1 (en) Passive speaker system
US6320970B1 (en) High frequency compression drivers
AU2003217250A1 (en) Low profile audio speaker
JPH0879876A (ja) 低音再生スピーカ
US3649776A (en) Omnidirectional horn loudspeaker
EP0886457A1 (fr) Enceinte acoustique d'ordinateur portable comportant un orifice
US4553628A (en) Speaker system
AU2407300A (en) Speaker system
US7225895B2 (en) Audio speaker with wobble free voice coil movement
US4466505A (en) Sound reproducing combination
JP2004343286A (ja) スピーカ装置
US5097514A (en) Equilateral tetrahedral speaker system
WO1991016798A1 (fr) Systeme a transducteurs audio
US6863152B1 (en) Low profile audio speaker
US4176253A (en) Current loaded pneumatically driven loudspeaker arrangements
JP3896675B2 (ja) スピーカ装置
US20020057819A1 (en) High frequency compression drivers
US3202773A (en) Electromagnetically damped speaker system
US20230145438A1 (en) Multifunctional Electromagnetic Transducer
US6014448A (en) Fluid coupled subwoofer acoustic enclosure system
JP7474518B2 (ja) オーディオラウドスピーカシステム

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AT AU BB BG BR CA CH DE DK ES FI GB HU JP KP KR LK LU MC MG MW NL NO PL RO SD SE SU

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE BF BJ CF CG CH CM DE DK ES FR GA GB GR IT LU ML MR NL SE SN TD TG

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

NENP Non-entry into the national phase

Ref country code: CA