EP0040281A1 - Lautsprecher- und Gehäusesystem mit digitalem codierendem phasenverschiebendem Aufteilungsfilter und selbständigem digitalem Leistungsstufensystem und modulare Methode zur Anwendung gegossener Einschübe - Google Patents

Lautsprecher- und Gehäusesystem mit digitalem codierendem phasenverschiebendem Aufteilungsfilter und selbständigem digitalem Leistungsstufensystem und modulare Methode zur Anwendung gegossener Einschübe Download PDF

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Publication number
EP0040281A1
EP0040281A1 EP80400691A EP80400691A EP0040281A1 EP 0040281 A1 EP0040281 A1 EP 0040281A1 EP 80400691 A EP80400691 A EP 80400691A EP 80400691 A EP80400691 A EP 80400691A EP 0040281 A1 EP0040281 A1 EP 0040281A1
Authority
EP
European Patent Office
Prior art keywords
horn
frame
digital
assembly
scr
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.)
Withdrawn
Application number
EP80400691A
Other languages
English (en)
French (fr)
Inventor
Walter Carl Thomas
Wayne William Thomas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LADY BEA ENTERPRISES Inc
Original Assignee
LADY BEA ENTERPRISES Inc
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 LADY BEA ENTERPRISES Inc filed Critical LADY BEA ENTERPRISES Inc
Priority to EP80400691A priority Critical patent/EP0040281A1/de
Priority to PCT/US1980/000889 priority patent/WO1981003595A1/en
Priority to AU71545/81A priority patent/AU7154581A/en
Publication of EP0040281A1 publication Critical patent/EP0040281A1/de
Withdrawn legal-status Critical Current

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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 
    • H04R1/24—Structural combinations of separate transducers or of two parts of the same transducer and responsive respectively to two or more frequency ranges
    • 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
    • H04R1/2819—Enclosures comprising vibrating or resonating arrangements of the bass reflex type for loudspeaker transducers
    • 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
    • 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 
    • H04R1/30—Combinations of transducers with horns, e.g. with mechanical matching means, i.e. front-loaded horns

Definitions

  • This invention lies in the field of acoustical loud-speakers. More particularly it concerns a construction for a loud speaker enclosure system which has superior acoustical properties.
  • the enclosure, or frame is in the form of a cube with side walls, top and bottom, but with no front or back wall.
  • a back wall is provided of a planar sheet of foamed plastic, such as styrofoam, which is attached to form a back closure of the frame.
  • a truncated pyramidal horn is provided of selected dimensions such that it will fit within the inner walls of the frame, with the wide portion of the horn at the front end of the frame.
  • the angle of the walls with respect to the axis of the horn is a selected angle.
  • the horn is truncated, and provided with a closure wall at the small end, such that the plane of the closure wall is substantially halfway between the front and back planes of the frame.
  • a circular opening is provided in the transverse wall closing the small end of the horn, and a low frequency loud-speaker of the cone type, is mounted to that closure wall with the speaker inside of the horn and the cone facing outwardly toward the rear wall of the frame.
  • Means are provided for mounting the horn to the frame at the front end thereof.
  • a suitable structure preferably made of foamed plastic, is provided for support of one or more higher frequency, small, loud-speakers attachable to the low frequency speaker.
  • the small speaker, or speakers are directed toward the front of the frame.
  • the front may be covered with a porous cloth or screen, such as is well-known in the art.
  • the frame is made in a cylindrical form, and the horn to which the speaker assembly is mounted, is a conical horn, of diameter at its wide end, which is smaller than the interior diameter of the frame, by a selected dimension.
  • the cone is made of foamed plastic of a selected material and wall thickness.
  • Figure 1 illustrates a front view of the invention, indicated generally by the numeral 10.
  • Figure 2 illustrates a side view, in section, of the same embodiment, taken along the plane 2-2 of Figure 1.
  • the enclosing structure of the assembly, or system is a frame of approximately cubical shape, indicated generally by numeral 12. This includes a top 18 and a bottom 20, with two sidewalls 2l and 22, fastened together to form a rigid enclosure.
  • the frame has no front or back walls.
  • the back is closed off by means of a panel 28 of foamed plastic, such as styrofoam, which is supported inside of the frame 12, and attached to strips 30 which are supported to the frame 12 by means of screws 31, and so on, as is well-known in the art.
  • the styrofoam panel 28 closing off the back end of the frame 13 can be of thickness in the range of 3/4" to 1". This provides sufficient strength and rigidity of the panel, but also because of the plastic properties of the material provides the ability to vibrate and transmit acoustical waves impinging on the inner surface and transmitting them outwardly from the back surface.
  • a horn indicated generally by the numeral 14.
  • this is a truncated pyramidal horn of square cross-sections, of selected angles 34 with respect to the axis of the horn.
  • This horn can be molded in one piece from suitable foamed plastic, and would have 4 tapering walls 36, and a transverse wall 40 closing off the small end of the horn.
  • the wall 40 has a central circular opening 38 of such a size as to approximately equal the diameter of a speaker 52 of the cone type, which is fastened by conventional means to the transverse wall 40.
  • the fastening can be by support ring 54 and screws 56.
  • the horn 14 At the large end of the horn 14 there are fixture- -.2 molded into the corners, such as will adapt for the tapered horn to fit snuggly into the corners of the frame 12.
  • the horn can be fastened to the frame 12 by means such as screws 44, or other suitable fasteners.
  • the walls 36 are spaced from the inner surface of the frame 12 by gaps 29, which are of width, a selected dimension 46.
  • the sound generated by the speaker 52 facing backward into the space 70 behind and outside of the horn, is transmitted outwardly partially by vibration of the back wall panel 28, and also by transmission of sound outside of the horn, and through the apertures, or slots, 29 and out to the front of the enclosure. There will be transmission of sound from the back surface of the cone of the speaker 52. There will also be lateral vibration, of the walls 36 of the horn, all of which together provides a flat response of considerable breadth, from very low to high frequencies.
  • the speaker 52 has an enclosure 58 around the magnet.
  • a support member 60 is molded of styrofoam, or other suitable foam plastic, with a cylindrical opening 62, adapted to fit over the magnet structure 58 of the speaker. This fixture 60 can be clamped around the cylindrical surface 64, so as to be held tightly to the magnet 58 of the speaker 52.
  • This foamed plastic structure 60 serves to support, in any selected manner, one or more higher frequency loud-speakers, such as a tweeter 66, which is mounted facing to the front, and one or more mid-range speakers 68A, 68B. These intermediate range speakers would complete the full range of frequency from the high tweeter frequencies down to the low frequencies of the woofer speaker 52.
  • the horn 14 is a symmetrical pyramid, and is fitted symmetrically into the square frame 12 to provide four openings 29 symmetrically positioned
  • Figure 3 there is shown a variation of Figure 1, in which the horn is comprised of a structure which has two parallel walls 76, and two sloping walls 36A, of slope angles similar to those of Figure 1. This could be fitted into a rectangular frame 12A, to provide two slots or openings 29A at top and bottom, similar to those of Figure 1.
  • the transverse wall 40 of the horn 14A in Figure 3 would be substantially identical to that of Figure 1, as would be the speaker assembly 16 for the two embodiments.
  • Figure 4 a third embodiment, which has a circular symmetry.
  • the frame 12B is a cylindrical, substantially rigid frame.
  • the back wall is closed with a circular styrofoam panel, not shown.
  • the front is partially closed by a conical horn 14B, which is fastened at a plurality of points to the interior surface of the frame, by means of cast members 42B, made of the same foam plastic of which the horn 14B is cast.
  • the transverse wall across the small end of the horn would be circular in shape and in the form of an annular wall, just sufficiently wide to support the loud speaker assembly 16 in a manner similar to that shown in Figure 2.
  • the horn is shown assembled symmetrically within the circular frame, providing an annular opening 29B between the outer perimeter of the horn and the inner wall of the frame.
  • the speaker assemblies 16 are identical, and are supported from the transverse wall 40 by conventional means, such as support rings 52 and screws 56 for example.
  • the slope angle of the walls of the horn are substantially the same, namely at an angle 34 to the axis of the horn 14, or to the walls of the enclosure 12.
  • This angle 34 of the wall of the horn 14 can be in the range of 15° - 30°. More preferably it can be in the range of 20° - 25 0. The optimum angle has been found to be 23°.
  • the wall thickness of the styrofoam horn 14, like that of the back panel 28 is in the range of 3/4" to 1".
  • the position of the transverse wall 40 is substantially in the midplane 46 between the front face 24 of the frame, and the back closure panel 28.
  • dimensions 47 and 48 are substantially equal, and half of the dimension 50.
  • One characteristic of this invention is that low frequency energy is directed into the space surrounding the horn, where part of the enclosing walls are made of flexible foamed plastic, whereas the high frequency energy is directed directly to the front of the enclosure, from inside of the horn.
  • Figures 8 and 10 are embodiments, utilizing the concept of polystyrene foam molded speaker inserts.
  • Figure 9 is a rigid outer housing for the inserts of Figures 8 and 10.
  • the outer housing 1 of Fig. 9 can be made of aluminum, plexiglass, or laminated wood, molded fibre glass (blown), or any material of rigid density.
  • the base 2 of Figure 9 can be of any suitable material to support the speaker.
  • the grill-cloth can be wrapped and glued to the polystyrene insert of Figures 8, 10, or 11 before being inserted from the back and slid to the front.
  • a rigid grill cloth (frame mounted) can be slid into an aluminum "L" shaped mounting ring 3 mounted on the end or inside of the outer housing 1.
  • the molded horn portion is the same inside as horn 14 in Figure 2.
  • the circular horn of Figure 9 is dimensionally identical to the circular horn of Fig. 4.
  • the circular holes 8 - Figure 8 - are for small mid-range speakers.
  • the tweeter mouth 7 of Fig. 8 is also dimensional as in Fig. 3.
  • a small tweeter opening 7 of Figure 10 is dimensional as shown in Figure 3.
  • the bass vents 11 of Figures 8 and 10 are dimensional as shown in Figure 1.
  • FIG 11 is shown an embodiment to accommodate many inserts of the configuration of Figures 8 and 10, which when.the holes 10 are filled with speaker inserts combine to make a large auditorium type speaker conducive to the multi-speaker digital power booster multiplexing system whose circuit is described in Figure 7.
  • This multi-speaker can be made of any semi-rigid material such as polystyrene, and inserted into a rigid frame.
  • FIG 5 is shown the electrical circuit for the enclosure system.
  • three bandwidth zones for the bass, midrange, and tweeter sections are utilized. However, one or more can be utilized separately.
  • variable resistor 11 The audio signal attenuated to pre-amp level by variable resistor 11 is fed to filter 2, which by known and standard methods filter the audio signal to include only the mid-range frequencies. (Nominally in the range of 250 Hz to 3 or 4 thousand Hz.).
  • the filtered audio signal emerges at 2a and is taken off at 15b where it is rectified by standard and known procedures and the negative going output of rectifier 15b fed into voltage controlled oscillator 4b.
  • Variable resistor 15c allows the VCO 4b to be positively biased to set the oscillation of VCO 4b in the proper frequency range with the negative going output of 15b decreasing the speed of VCO 4b as loud or more powerful fluctuations of 2a are passed by filter 2. This has the effect of slowing down the frequency sensitive control input l6b of Delay 5b.
  • VCO 4b automatically sets the drive time oscillation speed which determines the length of delay at various precise moments.
  • the automatically delayed analog audio signal is then fed to analog to digital converter 6b where (this can be' a 4 bit, 8 bit, 16 bit, or any size bit configuration depending on the amount of accuracy decoding desired - in this case, nominally an 8 bit word or byte is considered sufficient) via 14b the 8 bit word byte digital signal is fed to digital power booster amplified 7b which ultimately powers the mid-range speakers 9a and 9b.
  • the digital power booster amplifier will be described in Figure 6 and the following text.
  • the analog to digital converter 6b and digital amplified 7b will be synhronized by control clock 5 of Figure 6 to connection 11 of Figure 6, via line 22b of Figure 5.
  • FIG 6 the digital power amplifier section is shown.
  • the heart of this power amplifier is the SCR line 3, which overcomes the prior arts in-ability to digitally generate enough power to drive high power speakers.
  • SCR's are readily available in practically any power or amperage rating desirable. However they have one drawback which has eliminated them in the past for high power digital sound reproduction; namely when they are gated on by the control pulse they stay on until sufficiently reverse biased or their main source of power disconnected; turned off. This tended to eliminate the on and off requirements of digital audio reproduction for SCR's because audio frequencies do turn on and off at a relative high speed.
  • An out of phase negative pulse on line 6 is simultaneously fed to the H.F. A.C. power supply 4 while it simultaneously feeds a positive pulse via line 7 to the eight clock inputs of the 8 bit shift register 2; causing the new information to be loaded on the right side of the shift register 2a'b'c'd'e'f'g'h', while the SCR line 3 is turned off.
  • the clock 5 is loading the shift register 2abcdefgh (while its square wave is negative going to line 7) it is simultaneously exiting the positive going edge of its positive swing, via line 6, to the H.F. A.C. power supply 4 to send a powerful power pulse to read and execute the digital word byte present at the gates of the 8 SCR line 3, as read from 2 a'b'c'd'e'f'g'h'.
  • the digital to analog converters of Figure 5 are clocked in step or synchronization to keep the whole system in sync, or step with itself.
  • the resistor ladder 12 is made up of 8 resistors of proper wattage and resistance to handle the power amperage rating selected for the H.F. A.C. power supply 4 (this determined by the power requirements of the speakers).
  • R the value for R
  • it is binarily multiplied according to the ⁇ ⁇ procedures (i.e. ⁇ X R, 6X R, C X R, ⁇ X R, h X R, g X R, f X R, e X R)
  • ⁇ ⁇ procedures i.e. ⁇ X R, 6X R, C X R, ⁇ X R, h X R, g X R, f X R, e X R
  • the digital booster power lines A,B & C of Figure 5 can optionally draw their power and synchronizing clock pulses from a single clock and H.F. A.C. power supply; in which case H.F. A.C. power supply 4 of Figure 6 would set or designed at the maximum power requirements to handle the amperage drain of all the digital booster power lines, and clock 5 of Figure 5 set at maximum speed (i.e. at least 50,000 Hz to give a 25 kHz frequency response for the system. In this case filtering of the bandwidth zones would rely entirely upon the conventional filters 1,2 & 3 of Figure 5.
  • the maximum frequency allowed to be amplified is held to 250 Hz by setting the control clock 4 of Figure 6 at 500 Hz (using the rule of thumb 2X factor any frequencies over approximately 250 Hz simply would not be decoded). Additionally by specifying a high volt/amp H.F. A.C. power supply the bass frequencies decoded would be attenuated. (The H.F. A.C. power supply in this configuration oscillating at 500 Hz in sync with clock 5 of Figure 5).
  • FIG 7 a multi-speaker enclosure installation in a large auditorium or system.
  • the digital audio words of line A,B & C can be taken off at data busses l4a, 14b & 14c of Figure 5 and fed to any number of the above described speaker systems 1 containing, individually, only the digital amplifiers of Figure 6.
  • the clock sync pulse output of 11 Figure 6 and H.F. A.C. power supply output 14 of Figure 6 being supplied to all the speakers or systems externally.
  • These "slave" speaker enclosures would physically be the same as in Figure 1 but would only have the electronics as shown from the right of dotted line 18 of Figure 5, with external encoding via data busses 14a, 14b, and 14c, and sync from output 11 of Figure 6 and H.F.
  • A.C. power supply output 14 of Figure 6. (Again optionally, one feed of sync and H.F. A.C. could power any number of speakers or systems as long as clock 5 of Figure 6 speed was approximately 50 kHz, or two times the frequency response desired, and H.F. A.C. power supply 4 of Figure 6 was of sufficient amperage to meet the requirenents of the additional slave units or systems.)

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)
EP80400691A 1980-05-20 1980-05-20 Lautsprecher- und Gehäusesystem mit digitalem codierendem phasenverschiebendem Aufteilungsfilter und selbständigem digitalem Leistungsstufensystem und modulare Methode zur Anwendung gegossener Einschübe Withdrawn EP0040281A1 (de)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP80400691A EP0040281A1 (de) 1980-05-20 1980-05-20 Lautsprecher- und Gehäusesystem mit digitalem codierendem phasenverschiebendem Aufteilungsfilter und selbständigem digitalem Leistungsstufensystem und modulare Methode zur Anwendung gegossener Einschübe
PCT/US1980/000889 WO1981003595A1 (en) 1980-05-20 1980-07-18 Multi-way horn loudspeaker enclosure with electrical reverberation and digital power amplifier
AU71545/81A AU7154581A (en) 1980-05-20 1980-07-18 Loud speaker and enclosure system with digital encoding phaseshifted crossover network and self contained digital power drive system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP80400691A EP0040281A1 (de) 1980-05-20 1980-05-20 Lautsprecher- und Gehäusesystem mit digitalem codierendem phasenverschiebendem Aufteilungsfilter und selbständigem digitalem Leistungsstufensystem und modulare Methode zur Anwendung gegossener Einschübe

Publications (1)

Publication Number Publication Date
EP0040281A1 true EP0040281A1 (de) 1981-11-25

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EP80400691A Withdrawn EP0040281A1 (de) 1980-05-20 1980-05-20 Lautsprecher- und Gehäusesystem mit digitalem codierendem phasenverschiebendem Aufteilungsfilter und selbständigem digitalem Leistungsstufensystem und modulare Methode zur Anwendung gegossener Einschübe

Country Status (2)

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EP (1) EP0040281A1 (de)
WO (1) WO1981003595A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996004764A1 (en) * 1994-08-02 1996-02-15 Philips Electronics N.V. Apparatus including a loudspeaker unit, loudspeaker unit, and housing for a loudspeaker unit
WO2005081576A1 (en) * 2004-02-20 2005-09-01 Jamo International Aps Loudspeaker surround system

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1891968A (en) * 1932-02-25 1932-12-27 William C Bidwell Loud-speaker apparatus
FR768463A (fr) * 1934-02-10 1934-08-07 Andre Le Conte Et Co Perfectionnements aux haut-parleurs
FR908709A (fr) * 1942-03-31 1946-04-17 Nouveau système de baffle pour haut-parleurs électrodynamiques
US3129782A (en) * 1961-05-04 1964-04-21 James Willis Hughes Public address apparatus
US3235028A (en) * 1965-02-25 1966-02-15 William H Quinion High fidelity speaker enclosure
DE1512746A1 (de) * 1967-05-27 1969-07-17 Philips Patentverwaltung Lautsprecherbox
US3529691A (en) * 1969-05-27 1970-09-22 Fred A Wesemann Twin equilateral sound speaker enclosure
US4130174A (en) * 1977-05-25 1978-12-19 Audioanalyst, Inc. Loudspeaker
EP0008274A1 (de) * 1978-08-16 1980-02-20 Dominique Launay Unidirektionales akustisches Gehäuse

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3835256A (en) * 1973-07-09 1974-09-10 H Wieder Loudspeaker enclosure
US3912866A (en) * 1974-01-30 1975-10-14 Showsound Inc Folded bass horn speaker
US3931867A (en) * 1975-02-12 1976-01-13 Electrostatic Research Corporation Wide range speaker system
US4227051A (en) * 1979-02-26 1980-10-07 Thomas Wayne W Loud speaker and enclosure system

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1891968A (en) * 1932-02-25 1932-12-27 William C Bidwell Loud-speaker apparatus
FR768463A (fr) * 1934-02-10 1934-08-07 Andre Le Conte Et Co Perfectionnements aux haut-parleurs
FR908709A (fr) * 1942-03-31 1946-04-17 Nouveau système de baffle pour haut-parleurs électrodynamiques
US3129782A (en) * 1961-05-04 1964-04-21 James Willis Hughes Public address apparatus
US3235028A (en) * 1965-02-25 1966-02-15 William H Quinion High fidelity speaker enclosure
DE1512746A1 (de) * 1967-05-27 1969-07-17 Philips Patentverwaltung Lautsprecherbox
US3529691A (en) * 1969-05-27 1970-09-22 Fred A Wesemann Twin equilateral sound speaker enclosure
US4130174A (en) * 1977-05-25 1978-12-19 Audioanalyst, Inc. Loudspeaker
EP0008274A1 (de) * 1978-08-16 1980-02-20 Dominique Launay Unidirektionales akustisches Gehäuse

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996004764A1 (en) * 1994-08-02 1996-02-15 Philips Electronics N.V. Apparatus including a loudspeaker unit, loudspeaker unit, and housing for a loudspeaker unit
US5771304A (en) * 1994-08-02 1998-06-23 U.S. Philips Corporation Apparatus including a loudspeaker unit, loudspeaker unit, and housing for a loudspeaker unit
WO2005081576A1 (en) * 2004-02-20 2005-09-01 Jamo International Aps Loudspeaker surround system

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