US3112006A - Loudspeaker enclosures - Google Patents

Loudspeaker enclosures Download PDF

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US3112006A
US3112006A US87909A US8790961A US3112006A US 3112006 A US3112006 A US 3112006A US 87909 A US87909 A US 87909A US 8790961 A US8790961 A US 8790961A US 3112006 A US3112006 A US 3112006A
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loudspeaker
enclosure
panels
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00Details of transducers, loudspeakers or microphones
    • H04R1/20Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/28Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
    • H04R1/2807Enclosures comprising vibrating or resonating arrangements
    • H04R1/2861Enclosures comprising vibrating or resonating arrangements using a back-loaded horn
    • H04R1/2865Enclosures comprising vibrating or resonating arrangements using a back-loaded horn for loudspeaker transducers

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  • a loudspeaker enclosure which has some lfeatures in common with the enclosure of my prior application, but which involves simplifications and impovements #and 1s particularly suitable for use as a stereophonic de-vice.
  • the essential differences with respect to the loudspeaker enclosure of my prior application are: (l) lthe capability of using a single wide range speaker with consequent reduction in cost, (2) the coaction of the supporting panel with the wall and oor to form a corner-horn type o-f mouth improves the loading upon the speaker in the bass range, (3) the downward disposition of the mouth which permits of transmitting the uttenmost low notes through coupling to .the floor, (4) the quarter wave air column is extended outwardly to the terminus of the mouth, reducing the anti-resonant frequency with consequent extension of the bass range, (5) the area of the mouth terminus may be controlled by employing the correct elevation of the superstructure from the floor so that the area of the mouth terminus can be made either equal or greater than the larea of the intermediate passage with consequent increase in radiated sound power, (6) the structure is compact and convenient for use in the home, and (7) the enclosure is particularly suited for use as -a stereophonic device.
  • FIGURE 1 Iis a vertical central sectional View of a preferred embodiment of the invention taken approximately on the line 1--1 of FIG. 2;
  • FIG. 2 is tan end elevational view of the loudspeaker enclosure of FIG. 1 as seen from the lright hand end;
  • FIG. 3 is a front elevational view of another preferred embodiment of Ithe invention with the speaker facing in a forward direction;
  • FIG. 4 is a vertical sectional view taken approximately on the line 4-4 of FIG. 3;
  • FIG. 5 is la diagrammatic view of the acoustical circuit as represented by the approximate electrical analogs.
  • FIG. 6 is a diagrammatic view showing the variation With frequency of Ithe motional impedance of the loudspeaker housed in the loudspeaker enclosure of the present invention.
  • FIGS. 1 and 2 of the drawings in which ya preferred embodiment of the invention is illust-rated, a pair of loudspeaker enclosures is shown as disposed at opposite ends or sides of ra cabinet RPC in which a record player (not shown) or the like may be disposed.
  • Each of the enclosures in accordance with the invention and in a practical and useful embodiment can have an exterior Width of the order of 14 to 18 inches, an exterior depth of thefsame order, and a total height in feet of where fo is the primary resonance of the loudspeaker in free air in cycles per second.
  • the enclosure preferably includes a horizontal top wall panel 10, .and vertical side wall panel-s connected to and extending downwardly from said top wall panel 10 and including vertical front ⁇ and rear ywall panels 11 and 12, an inner vertical end wall panel A13, and an outer vertical exterior or end Wall panel y15.
  • the panel 12 may be advantageously disposed against the vertical wall 14 of a room or other enclosure and the panel 13 extends downwardly to the floor on which the enclosure is supported and with the other panel 13 ⁇ of the other speaker enclosure can serve as a support.
  • the panel 13 is prefenaibiy of a width to serve a baille yand with the Wall 14 closes two vertical sides of the space below the enclosure.
  • An interior baille which includes a battle panel 16 extending inwardly and upwardly at an inclination with respect to the lower terminus of the panel 15, extends between the vertical wall panels 11 and 12 and has an inclined panel 17 extending upwardly therefrom which also extends to and between the panels 11 and 12.
  • the panels 10, @11, 12, 15, '16 and 17 may be made of any desired material, such as wood, plywood, Veneered shipboard, ,and the like and panels of a thickness of threequarters of fan inch have been found satisfactory.
  • 'Ihe vertical supporting panel 13 may be made of the same material as the panels just referred Ito, but is preferably of double thickness.
  • the interior of the enclosure preferably has reinforcing framing members '18 horizontally disposed therein.
  • the exterior panel 15 has a loudspeaker diaphragm opening 19 therethrough and is adapted to support a loudspeaker '20' secured thereto in any desired manner with one surface 20a of the speaker 'diaphragm facing outwardly and the other surface 20b being faced inwardly.
  • the loudspeaker 20 may be of -any preferred type such as an electro-magnetic or an electro-static speaker.
  • the loudspeaker 20 has a damping ring 21 of any 3 suitable material applied thereto :and held thereon.
  • the damping ring 21 may be of any desired construction but for the purposes of the present invention, a damping ring similar to that sho-wn in the application above identified is preferably e-mployed consisting of a ring 40 of glass wool snugly fitted within a cowl 41.
  • the space within the wall panels 11, 1.2 and 15 and the supporting panel 1.3 has an interior throat portion 36 bounded by the baflles 16 and 17, and the lower portions of :the fwaill panels 11, 12 and 15.
  • the space within the wall panels 11, 12, 13 and 15 also includes a space 31, functioning as an energy sink 31, communicating with the throat portion 30 and bounded by the top panel 10 and upper portions of the panels 11, 12, 13 and 15.
  • the space within the wall panels 11, 12 and 15, and the supporting panel 13 also includes an intermediate passage portion 35 extending down-ward Ifrom the energy sink 31 and is bounded by the architects 126 and 17 and the lower port-ions o-f the panels 11, 12 and 13, and communicates through a mouth portion 32 with the outer air, the mouth terminus 32a lying in the planes of the panels 11 and 15 projected downwardly to the iloor 14a of the room.
  • Va speaker enclosure at only one end of the cabinet RPC will suffice, but for stereophonic use, two spaced enclosures are provided with a phonoradio compartment RPC therebetween.
  • FIGS. 3 and 4 another orientation of the loud speaker 2t is shown with the speaker 20 lfacing away lfrom the wall 14 of the room, with a horizontal baffle panel 16a and inclined baille panel 17a and with an opening or aperture 19b in the front wall panel 11a at which one tace of the diaphragm of the loudspeaker 20 is exposed.
  • the enclosure in accordance with the invention makes use of the quarter-wave action of a folded air column to establish an anti-resonance at and near Ithe primary free air resonance frequency of a loudspeaker.
  • the enclosure resembles an organ pipe ⁇ closed at one end and folded once.
  • the proportions of the air column are, however, incompatible with those of an organ pipe or resonant tube and are in fact more those of a box.
  • the present invention resembles the Helmholtz resonator, which -is also known in one of its forms as the bassreex enclosure.
  • the interior throat portion 30 At
  • the mouth terminus 32a encompasses van area several times that of the interior throat portion 30, the latter area taken horizontally, and the ratio of these ⁇ areas multiplies, by impedance transformation, the useful load upon the loudspeaker diaphragm surface 20h of FIG. 1.
  • the present invention resembles a small corner horn 'of the type familiar in this art.
  • the enclosure in accordance with the present invention is disqualified, however, by reason of the large reactive impedance at the fold (the energy sink 31) 'and by reason of the flared orifice at the outer end of the air column.
  • the enclosure in accordance with the present invention is disqualified because the antiresonance is established by the length of the air column, rather than by restriction of area as in the vent of a bass-reflex enclosure.
  • the air column and the compliant air volume are coterminous and in eifect fvibrate in two modes.
  • the enclosure in accordance with the present invention is disqualliiied (l) by the pronounced quarter-wave antiresonance of the air column and (2) by the shortness of the air column with respect to the wavelengths transmitted.
  • Horns must encompass at least several wavelengths from throat to mouth; and any air column, no matter what its ilare, becomes a simple discontinuity at its outer end when shorter in length than a quarter wave. (See L. L. Beranek, Acoustics, McGraw- Hill Book Co., 1954; page 2.72.)
  • the present structure is a three-way acoustical hybrid whose behavior is regulated (l) by its structure and proportions and (2) by the use of dissipative damping.
  • the network MtRbCbMm is a lowpass iilter of the T configuration. It is known that such a network, when properly proportioned, can be put to use as :an impedance transformer; when the network is matched to the internal impedance of the driver at one end and to the load impedance at the other the maximum trans-fer of energy is achieved.
  • curve A illustrates the rise in the motional impedance of a typical electromagnetic loudspeaker at its free air resonance point f2.
  • Curve B shows the similar ytree ai-r performance with a damping ring (such as 21 in FIGS. 1 and 2) attached to the speaker near the back Zlib of the diaphragm.
  • Curve ⁇ C shows the variation 'in inotional impedance of the same loudspeaker within the enclosure of FlGS. 1 and 2 with the damping ring 2l in place. These inotional impedances appear as voltages at the terminals of the loudspeaker woice coil.
  • Four frequency points are manned in FflG. 6:
  • f1 series resonance of Ms, CS, Mt and Mm (of FlG. 5)
  • f2 series resonance of Ms with Cs in free air
  • 3 series resonance of MS
  • Cs, Mt, and Cb f4 antiresonance of series branch Ms, Cs and Mt and shunt branch CDM
  • a loudspeaker enclosure for use along a vertical room wall and in spaced relation to the room oor having a plurality of spaced vertical Wall panels including t-wo antenne side wall panels and front ⁇ and rear wall panels, said vertical wall panels being vertically connected and one of said side wall panels extending downwardlyto the room door, a top wall panel closing said vertical panels, a baffle nieniher connected to rone of said vertical panels and to an opposed pair of said vertical panels and extending upwardly and terminated spaced relationship to said top wall panel, said baile providing on one ⁇ face thereof with its connected vertical panels an interior throat portion .and on the other face thereof with said opposite pair of connected vertical panels and with an opposing vertical panel an intermediate passage portion, the space within said vertical panels and above said baille and below said top wall panel providing an energy sink.
  • said energy sink being larger than said interior throat portion, the lspace below said vertical wall panels and to the roonn door providing a mouth por-tion terminating immediately below said vertical panels, and a loufdspearcer mounted at one side of said throat portion and having at least one diaphragm face thereof in ⁇ corranunication with said throat portion, said interior throat, energy sink, intermediate passage and mouth portions providing a folded air column no greater in length than a quarter wave of sound in air at the primary resonance frequency of said ⁇ loudspeaker.

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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)

Description

Nov. 26, 1963 A. H. ROBERTS 3,112,006
LoUDsPEAKER ENcLosuREs Filed Feb. s, 1961 m5 C: R;
SPEAKER lu i INVENTOR. ALFRED H.RoBERTs TQM# E FRELENCY P3 c, ATTORNEY United States Patent O 3,112,006 LOUDSPEAKER ENCLOSURES Alfred H. Roberts, 1615 Monk Road, Gladwyne, Pa. Filed Feb. 8, 1961, Ser. No. 87,909 1 Claim. (Cl. 181-31) This invention relates to loudspeaker enclosures.
in my prior application for patent for loudspeaker enclosures, Serial No. 803,856, tiled April 3, 1959, now U.S. Patent No. 2,978,060, there is disclosed a loudspeaker enclosure which has certain properties of a horn, of a Helmholtz resonator or basssreflex enclosure, and of a pipe folded once, but which does not satisfy all the criteria for any one of these lthree types of couplers.
In accordance with the present invention, a loudspeaker enclosure is provided which has some lfeatures in common with the enclosure of my prior application, but which involves simplifications and impovements #and 1s particularly suitable for use as a stereophonic de-vice.
The essential differences with respect to the loudspeaker enclosure of my prior application are: (l) lthe capability of using a single wide range speaker with consequent reduction in cost, (2) the coaction of the supporting panel with the wall and oor to form a corner-horn type o-f mouth improves the loading upon the speaker in the bass range, (3) the downward disposition of the mouth which permits of transmitting the uttenmost low notes through coupling to .the floor, (4) the quarter wave air column is extended outwardly to the terminus of the mouth, reducing the anti-resonant frequency with consequent extension of the bass range, (5) the area of the mouth terminus may be controlled by employing the correct elevation of the superstructure from the floor so that the area of the mouth terminus can be made either equal or greater than the larea of the intermediate passage with consequent increase in radiated sound power, (6) the structure is compact and convenient for use in the home, and (7) the enclosure is particularly suited for use as -a stereophonic device.
It is the principal object of the present invention to provide a loudspeaker enclosure having an improved low audible frequency response which economical of space and materials.
It is a further object of the present invention to provide a loudspeaker enclosure -which is efficient in the reproduction of sound yet is capable of operationwith loudspeakers having diver-se operational properties.
It is a further object of the present invention to provide a loudspeaker enclosure in which the speaker fis supponted by a panel which functions `with the wall and floor of the room in which the encl-osure is used to provide an improved type of discharge.
It is a further object of the present invention to provide a loudspeaker enclosure in which a preferred emf bodiment has provisions for the direct delivery of the speaker output on one side of the speaker and indirect delivery from the other face of the diaphragm through an elongated path which includes 1an energy sink.
Other objects and advantageous features of the invention will be apparent from the description and claim.
The nature and characteristic features of the invention will be more readily understood from the following description, taken in connection with the accompanying drawings forming pant thereof, in which:
FIGURE 1 Iis a vertical central sectional View of a preferred embodiment of the invention taken approximately on the line 1--1 of FIG. 2;
FIG. 2 is tan end elevational view of the loudspeaker enclosure of FIG. 1 as seen from the lright hand end;
FIG. 3 is a front elevational view of another preferred embodiment of Ithe invention with the speaker facing in a forward direction; v
ICC
FIG. 4 is a vertical sectional view taken approximately on the line 4-4 of FIG. 3;
FIG. 5 is la diagrammatic view of the acoustical circuit as represented by the approximate electrical analogs; and
FIG. 6 is a diagrammatic view showing the variation With frequency of Ithe motional impedance of the loudspeaker housed in the loudspeaker enclosure of the present invention.
It should, of course, be understood that the description and drawings herein `are illustrative merely, and that various modiiications and changes can be made in the structure disclosed without departing from the spirit of the invention.
Like numerals refer to like parts throughout the several views.
Referring nou more particularly to FIGS. 1 and 2 of the drawings in which ya preferred embodiment of the invention is illust-rated, a pair of loudspeaker enclosures is shown as disposed at opposite ends or sides of ra cabinet RPC in which a record player (not shown) or the like may be disposed.
Each of the enclosures in accordance With the invention and in a practical and useful embodiment can have an exterior Width of the order of 14 to 18 inches, an exterior depth of thefsame order, and a total height in feet of where fo is the primary resonance of the loudspeaker in free air in cycles per second.
The enclosure preferably includes a horizontal top wall panel 10, .and vertical side wall panel-s connected to and extending downwardly from said top wall panel 10 and including vertical front `and rear ywall panels 11 and 12, an inner vertical end wall panel A13, and an outer vertical exterior or end Wall panel y15. The panel 12 may be advantageously disposed against the vertical wall 14 of a room or other enclosure and the panel 13 extends downwardly to the floor on which the enclosure is supported and with the other panel 13` of the other speaker enclosure can serve as a support. The panel 13 is prefenaibiy of a width to serve a baille yand with the Wall 14 closes two vertical sides of the space below the enclosure.
An interior baille is provided which includes a baiile panel 16 extending inwardly and upwardly at an inclination with respect to the lower terminus of the panel 15, extends between the vertical wall panels 11 and 12 and has an inclined panel 17 extending upwardly therefrom which also extends to and between the panels 11 and 12. The panels 10, @11, 12, 15, '16 and 17 may be made of any desired material, such as wood, plywood, Veneered shipboard, ,and the like and panels of a thickness of threequarters of fan inch have been found satisfactory.
'Ihe vertical supporting panel 13 may be made of the same material as the panels just referred Ito, but is preferably of double thickness.
The interior of the enclosure preferably has reinforcing framing members '18 horizontally disposed therein. The panels, at their meeting margins, .are pretferalbly secured together in any desired manner so as to be rigid and airtight therealong.
As shown in lFIGS. 1 and 2, the exterior panel 15 has a loudspeaker diaphragm opening 19 therethrough and is adapted to support a loudspeaker '20' secured thereto in any desired manner with one surface 20a of the speaker 'diaphragm facing outwardly and the other surface 20b being faced inwardly.
The loudspeaker 20 may be of -any preferred type such as an electro-magnetic or an electro-static speaker.
f The loudspeaker 20 has a damping ring 21 of any 3 suitable material applied thereto :and held thereon. The damping ring 21 may be of any desired construction but for the purposes of the present invention, a damping ring similar to that sho-wn in the application above identified is preferably e-mployed consisting of a ring 40 of glass wool snugly fitted within a cowl 41.
The space within the wall panels 11, 1.2 and 15 and the supporting panel 1.3 has an interior throat portion 36 bounded by the baflles 16 and 17, and the lower portions of :the fwaill panels 11, 12 and 15. The space within the wall panels 11, 12, 13 and 15 also includes a space 31, functioning as an energy sink 31, communicating with the throat portion 30 and bounded by the top panel 10 and upper portions of the panels 11, 12, 13 and 15. The space within the wall panels 11, 12 and 15, and the supporting panel 13 also includes an intermediate passage portion 35 extending down-ward Ifrom the energy sink 31 and is bounded by the baies 126 and 17 and the lower port-ions o-f the panels 11, 12 and 13, and communicates through a mouth portion 32 with the outer air, the mouth terminus 32a lying in the planes of the panels 11 and 15 projected downwardly to the iloor 14a of the room.
For -monaural systems Va speaker enclosure at only one end of the cabinet RPC will suffice, but for stereophonic use, two spaced enclosures are provided with a phonoradio compartment RPC therebetween.
Referring now to FIGS. 3 and 4, another orientation of the loud speaker 2t) is shown with the speaker 20 lfacing away lfrom the wall 14 of the room, with a horizontal baffle panel 16a and inclined baille panel 17a and with an opening or aperture 19b in the front wall panel 11a at which one tace of the diaphragm of the loudspeaker 20 is exposed.
Reference will now be had to the -acoustical properties of the enclosure in accordance with the present invention.
The enclosure in accordance with the invention makes use of the quarter-wave action of a folded air column to establish an anti-resonance at and near Ithe primary free air resonance frequency of a loudspeaker. In this respect, the enclosure resembles an organ pipe `closed at one end and folded once.
The proportions of the air column, most particularly at the fold, are, however, incompatible with those of an organ pipe or resonant tube and are in fact more those of a box. Above the top edge of the interior bathe 17 and bounded by panels 10, 1-1, 12, 13 and 15 there exists an elastic volume of air which functions as an energy sink 31 at the antiresonance frequency. In this respect, the present invention resembles the Helmholtz resonator, which -is also known in one of its forms as the bassreex enclosure.
At |the inner end of the air column the interior throat portion 30 is located, and at the outer end, beyond the mouth portion 32, lies the mouth ter-minus 32a, peripheral to the solid angle defined by the room wall `114, the iloor 14a and the lower part of the panel 13, and lying in the planes of panels 11 and 15, as previously described. The mouth terminus 32a encompasses van area several times that of the interior throat portion 30, the latter area taken horizontally, and the ratio of these `areas multiplies, by impedance transformation, the useful load upon the loudspeaker diaphragm surface 20h of FIG. 1. In this respect, the present invention resembles a small corner horn 'of the type familiar in this art.
'Considered as a pipe, the enclosure in accordance with the present invention is disqualified, however, by reason of the large reactive impedance at the fold (the energy sink 31) 'and by reason of the flared orifice at the outer end of the air column.
Considered as a IHelmholtz resonator, the enclosure in accordance with the present invention is disqualified because the antiresonance is established by the length of the air column, rather than by restriction of area as in the vent of a bass-reflex enclosure. Within the energy sink 31, .the air column and the compliant air volume are coterminous and in eifect fvibrate in two modes.
Considered as a horn, the enclosure in accordance with the present invention is disqualliiied (l) by the pronounced quarter-wave antiresonance of the air column and (2) by the shortness of the air column with respect to the wavelengths transmitted. Horns must encompass at least several wavelengths from throat to mouth; and any air column, no matter what its ilare, becomes a simple discontinuity at its outer end when shorter in length than a quarter wave. (See L. L. Beranek, Acoustics, McGraw- Hill Book Co., 1954; page 2.72.)
-Undesired resonances, both longitudinal and transverse, must be avoided and these may be eliminated or suppressed (l) by diverting higher frequencies from the loudspeaker by means of an electrical crossover network, (2) by proper design of the damping ring, which discriminates against higher rfrequencies, and (3) by placement of acoustically absorbent material within the interior throat portion and/ or energy sink portion of the coupler, either as a blanket lining or a stuiiing, and (4) by the inherent character of the invention, wherein the transverse dimensions become comparable to a wavelength at frequencies -within the lower midrange of audibility, thus giving rise to dissonant weaker resonances in several modes and -in turn smoothing the frequency response.
The present structure is a three-way acoustical hybrid whose behavior is regulated (l) by its structure and proportions and (2) by the use of dissipative damping.
The electrical analogs shown in FIG. 5 aid in understanding the operation of the present invention, making clear its `differences from the enclosures heretofore available.
Referring now more particularly to FIG. 5, the acoustical properties of the present invention are described in the electrical impedance analog as follows:
Cs=Compliance of the elastic suspension of the loudspeaker diaphragm Rs=Resistance Iof the speaker suspension lumped with radiation res-istance encountered by the `face of the diaphragm 2Go Ms=Inertance of loudspeaker moving system lumped 'with that of the air lying immediately in yfront of the Idiaphragm 20a Rd=Dissipative resistance introduced close to the diaphragm 20 by acoustically absorbent material such as damping ring lZ1 Pc=Acoustical pressure acting upon the transmission network U=Volume velocity produced by Pc Mt=lnertance of interior throat portion 30 Rb=Dissipative resistance within energy sink 31 Cb=Complian`ce of air volume within energy sink 31 Mm=lnertance of mouth portion 32 and mouth terminus 32a Rar-:Radiation resistance at mouth terminus 32a Ub=Volurne 'velocity through energy sink 31 Ua=Volume velocity through mouth terminus 32a Ra and Rd vary approximately with the second power of the frequency at the .frequencies of interest y(i.e., below 500 c.p.s.).
It is apparent that the network MtRbCbMm is a lowpass iilter of the T configuration. It is known that such a network, when properly proportioned, can be put to use as :an impedance transformer; when the network is matched to the internal impedance of the driver at one end and to the load impedance at the other the maximum trans-fer of energy is achieved.
In the present invention, it is desired to extend the low frequency response below the point at which it starts to fall olf in a closed box. This lower cutoff point occurs when the inertances of the loudspeaker and the associated air load resonate with the compliances of the speaker suspension and the closed box, in series. This resonance occurs at 'a frequency higher than the primary free air resonance of the loudspeaker.
Referring now more particularly to FIG. 6 wherein impedances expressed in decibels are plotted as ordinates and frequency in cycles per second as abscissas, curve A illustrates the rise in the motional impedance of a typical electromagnetic loudspeaker at its free air resonance point f2. Curve B shows the similar ytree ai-r performance with a damping ring (such as 21 in FIGS. 1 and 2) attached to the speaker near the back Zlib of the diaphragm. Curve `C shows the variation 'in inotional impedance of the same loudspeaker within the enclosure of FlGS. 1 and 2 with the damping ring 2l in place. These inotional impedances appear as voltages at the terminals of the loudspeaker woice coil. Four frequency points are manned in FflG. 6:
f1=series resonance of Ms, CS, Mt and Mm (of FlG. 5) f2=series resonance of Ms with Cs in free air 3=series resonance of MS, Cs, Mt, and Cb f4=antiresonance of series branch Ms, Cs and Mt and shunt branch CDM,
he effect of the `damping ring 21, as shown in ourve B is clear. it has reduced the impedance liu-nip by approximately two to one. The antiresonant effect of the quarter wave air column as shown in curve C is also clear. Since the eloeities of the diaphragm and the antiresonant air column at the throat are in phase opposition, the excursion of the diaphragm f2 is reduced to its normal level. This in turn reduces harmonie distortion arising `from nonlinearitiesin the loudspeaker system and maximizes radiation at the mouth terminus 32a.
l claim: A loudspeaker enclosure for use along a vertical room wall and in spaced relation to the room oor having a plurality of spaced vertical Wall panels including t-wo antenne side wall panels and front `and rear wall panels, said vertical wall panels being vertically connected and one of said side wall panels extending downwardlyto the room door, a top wall panel closing said vertical panels, a baffle nieniher connected to rone of said vertical panels and to an opposed pair of said vertical panels and extending upwardly and terminated spaced relationship to said top wall panel, said baile providing on one `face thereof with its connected vertical panels an interior throat portion .and on the other face thereof with said opposite pair of connected vertical panels and with an opposing vertical panel an intermediate passage portion, the space within said vertical panels and above said baille and below said top wall panel providing an energy sink. in communication with said interior throat portion `and with sain intermediate passage portion, said energy sink being larger than said interior throat portion, the lspace below said vertical wall panels and to the roonn door providing a mouth por-tion terminating immediately below said vertical panels, and a loufdspearcer mounted at one side of said throat portion and having at least one diaphragm face thereof in `corranunication with said throat portion, said interior throat, energy sink, intermediate passage and mouth portions providing a folded air column no greater in length than a quarter wave of sound in air at the primary resonance frequency of said` loudspeaker.
References Cited in the file of this patent UNTED STATES PATENTS 2,765,864 Glenn Oct. 9, i956 2,866,513 White Dec. 30, 1958 2,985,229 Ferlsins May 30, 1961 OTHER REFERENCES Saunat (German printed application) L2G-852 VH1 aZlaZ, Aug. 30, 1956.
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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3165587A (en) * 1962-10-08 1965-01-12 Richard L Alderson Multiple-loudspeaker system
US3729061A (en) * 1970-02-27 1973-04-24 Pioneer Electronic Corp Speaker box
US3730291A (en) * 1970-08-18 1973-05-01 Neckermann Versand Kgaa Sound source cabinets
EP0132530A2 (en) * 1983-05-31 1985-02-13 Rainer Boscheinen Loudspeaker box
US5012889A (en) * 1989-11-30 1991-05-07 Rogersound Labs, Inc. Speaker enclosure
US5111905A (en) * 1989-11-30 1992-05-12 Rogersound Labs, Inc. Speaker enclosure
US8256566B1 (en) * 2011-08-19 2012-09-04 Rogersound Labs, LLC Speaker enclosure
US20220369027A1 (en) * 2019-06-28 2022-11-17 Nnnn As Directional loudspeaker

Citations (3)

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Publication number Priority date Publication date Assignee Title
US2765864A (en) * 1955-03-14 1956-10-09 Gen Electric Acoustic horn assembly
US2866513A (en) * 1952-11-24 1958-12-30 Edward V Bracken Apparatus for generating sound
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US2765864A (en) * 1955-03-14 1956-10-09 Gen Electric Acoustic horn assembly
US2986229A (en) * 1957-01-15 1961-05-30 Gen Dynamics Corp Loudspeaker enclosures

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3165587A (en) * 1962-10-08 1965-01-12 Richard L Alderson Multiple-loudspeaker system
US3729061A (en) * 1970-02-27 1973-04-24 Pioneer Electronic Corp Speaker box
US3730291A (en) * 1970-08-18 1973-05-01 Neckermann Versand Kgaa Sound source cabinets
EP0132530A2 (en) * 1983-05-31 1985-02-13 Rainer Boscheinen Loudspeaker box
EP0132530A3 (en) * 1983-05-31 1986-10-29 Rainer Boscheinen Loudspeaker box
US5012889A (en) * 1989-11-30 1991-05-07 Rogersound Labs, Inc. Speaker enclosure
US5111905A (en) * 1989-11-30 1992-05-12 Rogersound Labs, Inc. Speaker enclosure
US8256566B1 (en) * 2011-08-19 2012-09-04 Rogersound Labs, LLC Speaker enclosure
US20130043089A1 (en) * 2011-08-19 2013-02-21 Rogersound Labs Llc Speaker enclosure
US8397860B2 (en) * 2011-08-19 2013-03-19 Rogersound Labs, LLC Speaker enclosure
US20220369027A1 (en) * 2019-06-28 2022-11-17 Nnnn As Directional loudspeaker
US11882400B2 (en) * 2019-06-28 2024-01-23 Nnnn As Directional loudspeaker

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