EP0015186B1 - Three-channel acoustic system - Google Patents

Three-channel acoustic system Download PDF

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Publication number
EP0015186B1
EP0015186B1 EP80400180A EP80400180A EP0015186B1 EP 0015186 B1 EP0015186 B1 EP 0015186B1 EP 80400180 A EP80400180 A EP 80400180A EP 80400180 A EP80400180 A EP 80400180A EP 0015186 B1 EP0015186 B1 EP 0015186B1
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EP
European Patent Office
Prior art keywords
speaker
enclosures
channel
opening
cavity
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EP80400180A
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German (de)
French (fr)
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EP0015186A1 (en
Inventor
Michel Maille
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D'electronique Industrielle De Moulins S Ste
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SELIMO ELECT IND MOULINS
D'ELECTRONIQUE INDUSTRIELLE de MOULINS - SELIMO Ste
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    • 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
    • H04R1/2838—Enclosures comprising vibrating or resonating arrangements of the bandpass type
    • H04R1/2842—Enclosures comprising vibrating or resonating arrangements of the bandpass 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
    • H04R5/00—Stereophonic arrangements
    • H04R5/02—Spatial or constructional arrangements of loudspeakers

Definitions

  • the present invention relates to a triphonic acoustic reproduction system according to the preamble of the claims.
  • the present invention includes low frequency loudspeakers and more particularly low frequency loudspeakers for triphonic systems.
  • each channel comprises at the output a loudspeaker or an acoustic enclosure capable of reproducing the whole band of audible frequencies
  • each channel comprises at the output a loudspeaker, or an acoustic enclosure, capable of rendering the medium and high frequencies, that is to say the mid and high sounds, the low sounds being reproduced by a loudspeaker, or an acoustic speaker, common to the two channels.
  • the electrical signal from the output of each of the two amplifier channels is injected into an electronic filter which separates the low frequency component from the rest of the signal.
  • the two low frequency signals thus obtained are then injected into an electronic mixer, at the output of which the low frequency speaker is connected.
  • the present invention overcomes these drawbacks by developing a triphonic acoustic reproduction system which comprises a low frequency box usable at the output of an amplifier without the aid of any filter.
  • the frequency response of the box according to the invention can be adapted as a function of its position in the listening room and it is possible to very easily adjust the level of the low frequencies.
  • the triphonic acoustic reproduction system is characterized in that the device for restoring low-frequency signals consists of an acoustic box with two speakers each supporting at least one speaker so that the rear face of each top -speaker radiates inside its enclosure, the front face of each speaker radiating inside a cavity linked to the two speakers, the interior space of this cavity communicating with the outside by an opening of dimensions predetermined, this cavity and this opening being such that the high cut-off frequency of the box depends on the volume of the cavity and that the sound efficiency of the box is a function of the surface of said opening, a loudspeaker of this box being directly connected by output of the amplifier's guache channel and the other speaker being directly connected to the output of the right channel.
  • the two speakers are placed symmetrically face to face, the front face of the speakers then radiating into the cavity formed by the extension of the partitions of the two speakers, perpendicular to the speaker support faces ( s) and so as to leave an opening of predetermined width.
  • the triphonic system shown in FIG. 1 includes a stereophonic source 1 such as a record player or even a tape recorder. This source is connected to the inputs of a stereo 2 high fidelity amplifier.
  • the two channels, left 2G and right 2D of amplifier 2 have various preamplification, tone correction and power amplification circuits.
  • the left channel 2G therefore amplifies the signal from the left output SG of source 1 and the right channel 2D the signal from the right output SD.
  • the signal amplified by the 2D straight channel is then injected at the input of a 3D electronic filter.
  • a 3D electronic filter We thus have at the 7D output of this filter the low frequency component, for example frequencies below 200 Hz, of this amplified signal, and at the 8D output of frequencies above for example 200 Hz.
  • the 8D output is connected to a 5D loudspeaker allowing the reproduction of medium and treble sounds.
  • the signal amplified by the left channel 2G is injected at the input of a 3G electronic filter to the 3D filter of the right channel.
  • the 8G output of this filter is also connected to a 5G speaker allowing the reproduction of mid and treble sounds.
  • the two low-frequency outputs 7D and 7G of the two filters are connected to the inputs of a mixer 4, which, from the two low-frequency signals applied to its inputs, supplies the speaker 6 connected to its output with a low- frequency identical to the signals injected at the input and level adapted to this low frequency speaker 6.
  • a stereophonic source 1 conforming to that of FIG. 1, has its outputs, right SD and left SG, connected to the inputs of a high-fidelity amplifier with two 2D and 2G channels.
  • the low-frequency box comprises two identical speakers 10D and 10G, for example parallelepipedic, placed parallel one opposite the other at a predetermined distance.
  • Each of these speakers supports on one of its faces at least one speaker, 11D for the 10D speaker and 11G for the 10G speaker, so that a speaker of a speaker is facing a high - identical speaker from the other speaker.
  • enclosures can be of the closed type.
  • enclosures which avoid the phenomena of acoustic short circuit due to the compensation of the pressure between the front and rear faces of the diaphragm of the loudspeaker for low frequencies, oblige to have enclosures of large dimensions.
  • closed enclosures there appears a phenomenon of resonance at frequencies related to the dimensions of the enclosure. The lower the resonant frequency, the larger the dimensions of the speaker.
  • speakers of the counter-resonance or "bass reflex" type are adopted.
  • an opening, or vent is provided in the enclosure. This then behaves as a Helmholtz resonator. The dimensions of this enclosure are calculated so that the low energy low frequency sounds are amplified and emitted to the outside by the vent. This vent then behaves like a second speaker which only works for very low frequencies.
  • the two speakers are held symmetrically, that is to say the loudspeaker of one facing the loudspeaker of the other, and the vent of one facing the vent of the other.
  • the two closed or counter-resonant enclosures have their walls extended perpendicular to the speaker support faces so as to form a cavity 15.
  • This cavity 15 has an opening of width x, representing the distance between the end of the extension of the partition of enclosure 10D and the end of the extension of the partition of enclosure 10G.
  • the low frequency loudspeaker 11 D of the enclosure 10D is connected at the output of the right channel 2D of the amplifier 2 and the loudspeaker 11G of the enclosure 10G at the output of the left channel 2G.
  • These two speakers receive the amplified signals from source 1. These two signals are different for high frequencies and identical for low frequencies. Indeed, sound recordings, such as discs, are made in stereophony for high and medium frequencies, that is to say above about 200 Hz and can be affected in monophony for lower frequencies, because the ear human is no longer able to clearly locate the place of emission for very serious sounds.
  • the low frequency loudspeakers having only a very limited pass band because of the great inertia of their membrane, only radiate audibly for relatively low frequencies, for example less than 200 Hz.
  • the two speakers facing each other being supplied for low frequencies by identical signals, vibrate in phase and the assembly then operates in a so-called forced air manner.
  • the sounds emitted by the two loudspeakers are mixed in the volume delimited by two loudspeaker support faces, that is to say the volume of the cavity 15, and emitted towards the outside by the opening of width x.
  • the sound efficiency of the acoustic box according to the invention is linked to the dimensions of the opening through which the sound is emitted, that is to say the surface of width x through which the volume of the cavity 15 communicates with the outside. of the box. Any change in the distance between the two speakers, that is to say any change in the width x, causes a change in the emissive surface and therefore a change in the overall sound performance.
  • the two enclosures can be maintained at a variable distance, using a system of shims inserted between these two enclosures, or even using adjustable jacks or any other means capable of performing this function.
  • FIG. 3 represents a block diagram of a triphonic system equipped with a low frequency box according to a second embodiment of the invention.
  • the two speakers 10D and 10G are placed side by side and have a common partition.
  • the 11 G speaker (s) of the 10G speaker are placed in the same plane as the 11 G speaker (s) of the 10G speaker.
  • the front faces of these speakers radiate into a cavity 15 formed by the extension of the non-common partitions of the speakers 10D and 10G and by a wall covering the whole parallel to the speaker support faces.
  • This cavity 15 communicates with the outside through an opening 17, the dimensions of which condition the sound performance of the box.
  • the speaker 11D of the enclosure 10D, as well as a mid-high-range speaker 5D are connected at the output of the 2D channel of an amplifier 2, and the speaker 11G of the enclosure 10G, as well as a 5G mid-treble speaker are connected at the output of the 2G channel.
  • the loudspeakers 11 D and 11 G vibrate in phase, and the sounds emitted by each of them are mixed in the cavity 15, and emitted towards the exterior by the opening 17.
  • low-frequency subwoofers are mainly used in high-fidelity triphonic chains, but can also be used without disadvantage for the reproduction of bass sounds on a monophonic chain, or even a stereophonic chain, a subwoofer according to the invention being connected to each of the two ways.

Description

La présente invention concerne un système de reproduction acoustique triphonique selon la pre- ambule de la revendications.The present invention relates to a triphonic acoustic reproduction system according to the preamble of the claims.

Dans les systèmes monophoniques ou stéréophoniques classiques, il est très difficile de reproduire fidélement avec un seul haut-parleur, toute la gamme des fréquences audibles, car la bande passante d'un haut-parleur dépend de sa conception et des ses dimensions. Par exemple, pour la reproduction des sons aigus, la membrane du haut-parleur doit être légère et rigide, alors que par contre, pour la reproduction des sons graves, la membrane doit être aussi grande que possible et suspendue souplement. On utilise donc généralement, pour obtenir une bonne reproduction dans toute la gamme des fréquences audibles, des systèmes de haut-parleurs combinés dans un coffret commun de manière à former une enceinte acoustique unique large bande passante, ou encore dans des coffrets séparés, formant ainsi des enceintes basse, moyenne ou haute fréquence.In conventional monophonic or stereophonic systems, it is very difficult to reproduce faithfully with a single speaker, the whole range of audible frequencies, because the bandwidth of a speaker depends on its design and dimensions. For example, for the reproduction of high sounds, the diaphragm of the loudspeaker must be light and rigid, whereas on the other hand, for the reproduction of bass sounds, the membrane must be as large as possible and suspended loosely. In order to obtain a good reproduction in the whole range of audible frequencies, therefore, it is generally used to use speaker systems combined in a common box so as to form a single wideband acoustic enclosure, or even in separate boxes, thus forming low, medium or high frequency speakers.

La présente invention comporte les enceintes acoustiques basse fréquence et plus particulièrement les enceintes acoustiques basse fréquence pour les systèmes triphoniques.The present invention includes low frequency loudspeakers and more particularly low frequency loudspeakers for triphonic systems.

En effet, dans les systèmes triphoniques classiques, tout comme dans les systèmes stéréophoniques, le son est reproduit à partir de deux signaux électriques, l'un provenant de la voie droite d'un amplificateur et l'autre de la voie gauche. Cependant, alors qu'en stéréophonie, chaque voie comporte en sortie un haut parleur ou une enceinte acoustique capable de restituer toute la bande des fréquences audibles, en triphonie chaque voie comporte en sortie un haut-parleur, ou une enceinte acoustique, capable de restituer les fréquences moyennes et hautes, c'est-à-dire les sons médiums et aigus, les sons graves étant restitués par un haut-parleur, ou une enceinte acoustique, commun aux deux voies.Indeed, in classical triphonic systems, as in stereophonic systems, sound is reproduced from two electrical signals, one from the right channel of an amplifier and the other from the left channel. However, while in stereophony, each channel comprises at the output a loudspeaker or an acoustic enclosure capable of reproducing the whole band of audible frequencies, in triphony each channel comprises at the output a loudspeaker, or an acoustic enclosure, capable of rendering the medium and high frequencies, that is to say the mid and high sounds, the low sounds being reproduced by a loudspeaker, or an acoustic speaker, common to the two channels.

En effet, en triphonie classique, le signal électrique provenant de la sortie de chacune des deux voies de l'amplificateur est injecté dans un filtre électronique qui sépare la composante basse fréquence du reste du signal. Les deux signaux basse fréquence ainsi obtenus sont ensuite injectés dans un mélangeur électronique, à la sortie duquel est connecté le haut-parleur basse fréquence.Indeed, in conventional triphony, the electrical signal from the output of each of the two amplifier channels is injected into an electronic filter which separates the low frequency component from the rest of the signal. The two low frequency signals thus obtained are then injected into an electronic mixer, at the output of which the low frequency speaker is connected.

L'utilisation de tels circuits électroniques, filtres et mélangeur, présente quelques inconvénients, aussi bien du point de vue de la fiabilité que du point de vue du coût. En effet, ces circuits, de par leur utilisation en sortie de l'amplificateur doivent supporter des courants de valeurs relativement élevées.The use of such electronic circuits, filters and mixer has some drawbacks, both from the point of view of reliability and from the point of view of cost. Indeed, these circuits, by their use at the output of the amplifier must support currents of relatively high values.

La présente invention supprime ces inconvénients en élaborant un système de reproduction acoustique triphonique qui comporte un caisson basse fréquence utilisable en sortie d'un amplificateur sans l'aide d'aucun filtre. De plus, la réponse en fréquence du caisson selon l'invention peut être adaptée en fonction de sa position dans le local d'écoute et il est possible de régler très facilement le niveau des fréquences basses.The present invention overcomes these drawbacks by developing a triphonic acoustic reproduction system which comprises a low frequency box usable at the output of an amplifier without the aid of any filter. In addition, the frequency response of the box according to the invention can be adapted as a function of its position in the listening room and it is possible to very easily adjust the level of the low frequencies.

Le système de reproduction acoustique triphonique selon l'invention est caractérisé en ce que le dispositif de restitution des signaux à basse fréquence est constitué par un caisson acoustique à deux enceintes supportant chacune au moins un haut-parleur de manière que la face arrière de chaque haut-parleur rayonne à l'intérieur de son enceinte, la face avant de chaque haut-parleur rayonnant à l'intérieur d'une cavité liée aux deux enceintes, l'espace intérieur de cette cavité communiquant avec l'extérieur par un ouverture de dimensions prédéterminées, cette cavité et cette ouverture étant telles que la fréquence de coupure haute du caisson dépend du volume de la cavité et que le rendement sonore du caisson est fonction de la surface de ladite ouverture, un haut-parleur de ce caisson étant directement connecté en sortie de la voie guache de l'amplificateur et l'autre haut-parleur étant directement relié en sortie de la voie de droite.The triphonic acoustic reproduction system according to the invention is characterized in that the device for restoring low-frequency signals consists of an acoustic box with two speakers each supporting at least one speaker so that the rear face of each top -speaker radiates inside its enclosure, the front face of each speaker radiating inside a cavity linked to the two speakers, the interior space of this cavity communicating with the outside by an opening of dimensions predetermined, this cavity and this opening being such that the high cut-off frequency of the box depends on the volume of the cavity and that the sound efficiency of the box is a function of the surface of said opening, a loudspeaker of this box being directly connected by output of the amplifier's guache channel and the other speaker being directly connected to the output of the right channel.

Un caisson acoustique à deux enceintes supportant chacune au moins un haut-parleur de manière que la face arrière de chaque haut-parleur rayonne à l'intérieur de son enceinte est certes déjà connu par le brevet US 3076520 mais ce document ne suggère pas l'utilisation, conforme à la présente invention, d'un tel caisson pour reproduire exclusivement les fréquences basses, c'est-à-dire l'utilisation d'un tel caisson en tant que filtre coupe-haut.An acoustic box with two speakers each supporting at least one speaker so that the rear face of each speaker radiates inside its enclosure is certainly already known by US patent 3076520 but this document does not suggest the use, in accordance with the present invention, of such a box to reproduce exclusively the low frequencies, that is to say the use of such a box as a high-cut filter.

Selon un mode de réalisation de l'invention les deux enceintes sont placées symétriquement face à face, la face avant des haut-parleurs rayonnant alors dans la cavité formée par le prolongement des cloisons des deux enceintes, perpendiculairement aux faces support de haut-parleur(s) et de manière à laisser une ouverture de largeur prédéterminée.According to one embodiment of the invention, the two speakers are placed symmetrically face to face, the front face of the speakers then radiating into the cavity formed by the extension of the partitions of the two speakers, perpendicular to the speaker support faces ( s) and so as to leave an opening of predetermined width.

D'autres caractéristiques et avantages de l'invention ressortiront de la description suivante donnée à titre d'exemple non-limitatif et illustrée par les figures annexées qui représentent:

  • - la figure 1, un schéma synoptique d'un système triphonique classique;
  • - la figure 2, un schéma synoptique d'un système triphonique équipé d'un caisson acoustique basse fréquence selon un mode de réalisation de l'invention;
  • -la figure 3, un schéma synoptique d'un système triphonique équipé d'un caisson acoustique basse fréquence selon un second mode de réalisation de l'invention.
Other characteristics and advantages of the invention will emerge from the following description given by way of non-limiting example and illustrated by the appended figures which represent:
  • - Figure 1, a block diagram of a conventional triphonic system;
  • - Figure 2, a block diagram of a triphonic system equipped with a low-frequency acoustic box according to one embodiment of the invention;
  • FIG. 3, a block diagram of a triphonic system equipped with a low frequency acoustic box according to a second embodiment of the invention.

Le système triphonique représenté figure 1 comporte une source stéréophonique 1 telle qu'une platine tourne-disque ou encore un magnétophone. Cette source est connectée aux entrées d'un amplificateur haute fidélité 2 stéréophonique. Les deux voies, gauche 2G et droite 2D de l'amplificateur 2 comportent divers circuits de préamplification, de correction de tonalité et d'amplification de puissance. La voie gauche 2G amplifie donc le signal provenant de la sortie gauche SG de la source 1 et la voie droite 2D le signal provenant de la sortie droite SD.The triphonic system shown in FIG. 1 includes a stereophonic source 1 such as a record player or even a tape recorder. This source is connected to the inputs of a stereo 2 high fidelity amplifier. The two channels, left 2G and right 2D of amplifier 2 have various preamplification, tone correction and power amplification circuits. The left channel 2G therefore amplifies the signal from the left output SG of source 1 and the right channel 2D the signal from the right output SD.

Le signal amplifié par la voie droite 2D est ensuite injecté en entrée, d'un filtre électronique 3D. On dispose ainsi en sortie 7D de ce filtre de la composante basse fréquence, par exemple les fréquences inférieures à 200 Hz, de ce signal amplifié, et en sortie 8D des fréquences supérieures à par exemple 200 Hz.The signal amplified by the 2D straight channel is then injected at the input of a 3D electronic filter. We thus have at the 7D output of this filter the low frequency component, for example frequencies below 200 Hz, of this amplified signal, and at the 8D output of frequencies above for example 200 Hz.

La sortie 8D est connectée à un haut-parleur 5D permettant de restituer des sons médiums et aigus.The 8D output is connected to a 5D loudspeaker allowing the reproduction of medium and treble sounds.

Le signal amplifié par la voie de gauche 2G est injecté en entrée d'un filtre électronique 3G au filtre 3D de la voie de droite. La sortie 8G de ce filtre est elle aussi connectée à un haut-parleur 5G permettant de restituer les sons médiums et aigus.The signal amplified by the left channel 2G is injected at the input of a 3G electronic filter to the 3D filter of the right channel. The 8G output of this filter is also connected to a 5G speaker allowing the reproduction of mid and treble sounds.

Les deux sorties basse-fréquence 7D et 7G des deux filtres sont connectées aus entrées d'un mélangeur 4, qui à partir des deux signaux basse fréquence appliqués sur ses entrées, fournit au haut-parleur 6 connecté à sa sortie, un signal basse-fréquence identique aux signaux injectés en entrée et de niveau adapté à ce haut-parleur basse fréquence 6.The two low-frequency outputs 7D and 7G of the two filters are connected to the inputs of a mixer 4, which, from the two low-frequency signals applied to its inputs, supplies the speaker 6 connected to its output with a low- frequency identical to the signals injected at the input and level adapted to this low frequency speaker 6.

Ces filtres, connectés aux sorties de l'amplificateur haute fidélité c'est-à-dire aux sorties de ses étages d'amplification de puissance, doivent supporter des courants relativement élevés.These filters, connected to the outputs of the high fidelity amplifier, that is to say to the outputs of its power amplification stages, must support relatively high currents.

Une source 1 stéréophonique, conforme à celle de la figure 1, a ses sorties, droite SD et gauche SG, connectées aux entrées d'un amplificateur haute-fidélité à deux voies 2D et 2G.A stereophonic source 1, conforming to that of FIG. 1, has its outputs, right SD and left SG, connected to the inputs of a high-fidelity amplifier with two 2D and 2G channels.

Le caisson basse fréquence comporte deux enceintes identiques 10D et 10G, par exemple parallélépipédiques, placées parallèlement l'une en face de l'autre à une distance prédéterminée. Chacune de ces enceintes supporte sur une de ses faces au moins un haut-parleur, 11D pour l'enceinte 10D et 11G pour l'enceinte 10G, de manière qu'un haut-parleur d'une enceinte soit en regard d'un haut-parleur identique de l'autre enceinte.The low-frequency box comprises two identical speakers 10D and 10G, for example parallelepipedic, placed parallel one opposite the other at a predetermined distance. Each of these speakers supports on one of its faces at least one speaker, 11D for the 10D speaker and 11G for the 10G speaker, so that a speaker of a speaker is facing a high - identical speaker from the other speaker.

Ces enceintes peuvent être du type clos. Cependant de telles enceintes, qui évitent les phénomènes de court-circuit acoustique dus à la compensation de la pression entre les faces avant et arrière de la membrane du haut-parleur pour les fréquences basses, obligent à avoir des enceintes de dimensions importantes. En effet, dans les enceintes closes il apparaît un phénomène de résonance à des fréquences liées aux dimensions de l'enceinte. Plus la fréquence de résonance doit être basse, plus les dimensions de l'enceinte doivent être importantes.These enclosures can be of the closed type. However, such enclosures, which avoid the phenomena of acoustic short circuit due to the compensation of the pressure between the front and rear faces of the diaphragm of the loudspeaker for low frequencies, oblige to have enclosures of large dimensions. Indeed, in closed enclosures there appears a phenomenon of resonance at frequencies related to the dimensions of the enclosure. The lower the resonant frequency, the larger the dimensions of the speaker.

Selon un autre mode de réalisation de l'invention on adopte des enceintes du type à contre résonance ou "bass reflex". Dans ce cas, une ouverture, ou évent, est aménagée dans l'enceinte. Celle-ci se comporte alors en résonateur d'Helmholtz. Les dimensions de cette enceinte sont calculées de manière à ce que les sons basse fréquence de faible énergie soient amplifiés et émis vers l'extérieur par l'évent. Cet évent se comporte alors comme un second haut-parleur qui ne fonctionne que pour les fréquences très basses.According to another embodiment of the invention, speakers of the counter-resonance or "bass reflex" type are adopted. In this case, an opening, or vent, is provided in the enclosure. This then behaves as a Helmholtz resonator. The dimensions of this enclosure are calculated so that the low energy low frequency sounds are amplified and emitted to the outside by the vent. This vent then behaves like a second speaker which only works for very low frequencies.

Les deux enceintes sont maintenues symétriquement, c'est-à-dire le haut-parleur de l'une face au haut-parleur de l'autre, et l'évent de l'une face à l'évent de l'autre.The two speakers are held symmetrically, that is to say the loudspeaker of one facing the loudspeaker of the other, and the vent of one facing the vent of the other.

Les deux enceintes closes ou à contre résonance ont leurs parois prolongées perpendiculairement aux faces support de haut-parleurs de manière à former une cavité 15. Cette cavité 15 possède une ouverture de largeur x, représentant la distance entre l'extrémité du prolongement de la cloison de l'enceinte 10D et l'extrémité du prolongement de la cloison de l'enceinte 10G.The two closed or counter-resonant enclosures have their walls extended perpendicular to the speaker support faces so as to form a cavity 15. This cavity 15 has an opening of width x, representing the distance between the end of the extension of the partition of enclosure 10D and the end of the extension of the partition of enclosure 10G.

Le haut-parleur basse fréquence 11 D de l'enceinte 10D est connecté en sortie de la voie de droite 2D de l'amplificateur 2 et le haut-parleur 11G de l'enceinte 10G en sortie de la voie de gauche 2G.The low frequency loudspeaker 11 D of the enclosure 10D is connected at the output of the right channel 2D of the amplifier 2 and the loudspeaker 11G of the enclosure 10G at the output of the left channel 2G.

Ces deux haut-parleurs reçoivent les signaux amplifiés provenant de la source 1. Ces deux signaux sont différents pour les fréquences élevées et idendiques pour les fréquences basses. En effet, les enregistrements sonores, tels que les disques, sont effectués en stéréophonie pour les fréquences élevées et moyennes, c'est-à-dire supérieures à environ 200 Hz et peuvent être affectués en monophonie pour les fréquences inférieures, car l'oreille humaine n'est plus capable de localiser distinctement le lieu d'émission pour les sons très graves.These two speakers receive the amplified signals from source 1. These two signals are different for high frequencies and identical for low frequencies. Indeed, sound recordings, such as discs, are made in stereophony for high and medium frequencies, that is to say above about 200 Hz and can be affected in monophony for lower frequencies, because the ear human is no longer able to clearly locate the place of emission for very serious sounds.

D'autre part les haut-parleurs basse fréquence ne possédant qu'une bande passante très restreinte, du fait de la grande inertie de leur membrane, ne rayonnent de façon audible que pour des fréquences relativement basses, par exemple inférieures à 200 Hz.On the other hand the low frequency loudspeakers having only a very limited pass band, because of the great inertia of their membrane, only radiate audibly for relatively low frequencies, for example less than 200 Hz.

Les deux haut-parleurs face à face, étant alimentés pour les fréquences basses par des signaux identiques, vibrent en phase et l'ensemble fonctionne alors d'une manière dite à air pulsé. Les sons émis par les deux haut-parleurs sont mélangés dans le volume délimité par des deux faces support de haut-parleur, c'est-à-dire le volume de la cavité 15, et émis vers l'extérieur par l'ouverture de largeur x.The two speakers facing each other, being supplied for low frequencies by identical signals, vibrate in phase and the assembly then operates in a so-called forced air manner. The sounds emitted by the two loudspeakers are mixed in the volume delimited by two loudspeaker support faces, that is to say the volume of the cavity 15, and emitted towards the outside by the opening of width x.

Le reste du spectre sonore est reproduit par deux haut-parleurs médium-aigu, l'un 5D étant connecté en sortie droite de l'amplificateur et l'autre 5G en sortie gauche.The rest of the sound spectrum is reproduced by two mid-high-range speakers, one 5D being connected to the amplifier's right output and the other 5G to the left output.

D'autre part en jouant sur le volume de chacune des enceintes 10D et 10G, il est possible d'agir sur la fréquence basse d'accord du haut-parleur dans son enceinte close ou à contre résonance.On the other hand by playing on the volume of each of the 10D and 10G speakers, it is possible to act on the low frequency of tuning of the speaker in its closed or counter-resonant enclosure.

En modifiant le volume de la cavité 15, il est possible de jouer sur la fréquence de coupure haute du caisson basse fréquence. Lorsque ce volume augmente la fréquence de coupure devient plus élevée, et lorsque le volume diminue, la fréquence de coupure devient plus faible.By modifying the volume of the cavity 15, it is possible to play on the high cut-off frequency of the low frequency box. When this volume increases the cutoff frequency becomes higher, and when the volume decreases, the cutoff frequency becomes lower.

Le rendement sonore du caisson acoustique selon l'invention est lié aux dimensions de l'ouverture par laquelle est émis le son, c'est-à-dire la surface de largeur x par laquelle le volume de la cavité 15 communique avec l'extérieur du caisson. Toute modification de la distance entre les deux enceintes, c'est-à-dire toute modification de la largeur x, entraîne une modification de la surface émissive et donc une modification du rendement sonore de l'ensemble.The sound efficiency of the acoustic box according to the invention is linked to the dimensions of the opening through which the sound is emitted, that is to say the surface of width x through which the volume of the cavity 15 communicates with the outside. of the box. Any change in the distance between the two speakers, that is to say any change in the width x, causes a change in the emissive surface and therefore a change in the overall sound performance.

Il est donc possible d'adapter le rendement sonore du caisson en fonction de sa position dans la pièce d'écoute en agissant sur la valeur de la largeur x. Pour ce faire, les deux enceintes peuvent être maintenues à une distance variable, à l'aide d'un système de cales intercalées entre ces deux enceintes, ou encore à l'aide de vérins réglables ou tout autre moyen pouvant assurer cette fonction.It is therefore possible to adapt the sound efficiency of the box according to its position in the listening room by acting on the value of the width x. To do this, the two enclosures can be maintained at a variable distance, using a system of shims inserted between these two enclosures, or even using adjustable jacks or any other means capable of performing this function.

En effet, lorsque le caisson est positionné, par exemple le coin d'une pièce, de ses quatre faces émissives de largeur x, si les enceintes sont parallélépipédiques, seules deux sont effectives puisque les deux autres sont obturées par le mur de la pièce. En augmentant la largeur x, on peut alors augmenter la surface émissive et remédier à cet inconvénient.Indeed, when the box is positioned, for example the corner of a room, with its four emissive faces of width x, if the speakers are parallelepiped, only two are effective since the other two are closed by the wall of the room. By increasing the width x, we can then increase the emissive surface and remedy this drawback.

La figure 3 représente un schéma synoptique d'un système triphonique équipé d'un caisson basse fréquence selon un second mode de réalisation de l'invention.FIG. 3 represents a block diagram of a triphonic system equipped with a low frequency box according to a second embodiment of the invention.

Les deux enceintes 10D et 10G sont placées côte à côte et possèdent une cloison commune. Le ou les haut-parleurs 11 G de l'enceinte 10G sont placés dans un même plan que le (ou les) haut-parleur(s) 11 G de l'enceinte 10G.The two speakers 10D and 10G are placed side by side and have a common partition. The 11 G speaker (s) of the 10G speaker are placed in the same plane as the 11 G speaker (s) of the 10G speaker.

Les faces avant de ces haut-parleurs rayonnent dans une cavité 15 formée par le prolongement des cloisons non communes des enceintes 10D et 10G et par une paroi coiffant le tout parallélement auf faces support de haut-parleurs.The front faces of these speakers radiate into a cavity 15 formed by the extension of the non-common partitions of the speakers 10D and 10G and by a wall covering the whole parallel to the speaker support faces.

Le volume de cette cavité 15 communique avec l'extérieur par une ouverture 17 dont des dimensions conditionnent le rendement sonore du caisson.The volume of this cavity 15 communicates with the outside through an opening 17, the dimensions of which condition the sound performance of the box.

Tout comme dans le cas de la figure 2, en jouant sur le volume des enceintes 10D et 10G, il est possible d'agir sur la fréquence basse d'accord du haut-parleur dans son enceinte qui peut être close ou à contre résonance, et en modifiant le volume de la cavité 15, il est possible d'agir sur la fréquence de coupure basse de caisson basse fréquence.As in the case of FIG. 2, by playing on the volume of the speakers 10D and 10G, it is possible to act on the low frequency of tuning of the loudspeaker in its enclosure which can be closed or in counter resonance, and by modifying the volume of the cavity 15, it is possible to act on the low cut-off frequency of the low-frequency box.

Le haut-parleur 11D de l'enceinte 10D, ainsi qu'un haut-parleur médium-aigu 5D sont connectés en sortie de la voie 2D d'un amplificateur 2, et le haut parleur 11G de l'enceinte 10G, ainsi qu'un haut-parleur 5G médium-aigu sont connectés en sortie de la voie 2G.The speaker 11D of the enclosure 10D, as well as a mid-high-range speaker 5D are connected at the output of the 2D channel of an amplifier 2, and the speaker 11G of the enclosure 10G, as well as a 5G mid-treble speaker are connected at the output of the 2G channel.

Tout comme à la figure 2, les haut-parleurs 11 D et 11 G vibrent en phase, et les sons émis par chacun d'eux sont mélangés dans la cavité 15, et émis vers l'extérieur par l'ouverture 17.As in FIG. 2, the loudspeakers 11 D and 11 G vibrate in phase, and the sounds emitted by each of them are mixed in the cavity 15, and emitted towards the exterior by the opening 17.

Ces caissons basse fréquence sont principalement utilisés dans les chaînes haute fidélité triphoniques, mais peuvent aussi être utilisés sans inconvénient pour la reproduction des sons graves sur une chaîne monophonique, ou encore une chaîne stéréophonique, un caisson conforme à l'invention étant connecté sur chacune des deux voies.These low-frequency subwoofers are mainly used in high-fidelity triphonic chains, but can also be used without disadvantage for the reproduction of bass sounds on a monophonic chain, or even a stereophonic chain, a subwoofer according to the invention being connected to each of the two ways.

Claims (8)

1. A triphonic acoustic reproduction system comprising an amplifier (2) for amplifying two channels, a left channel (2G) and a right channel (2D), connected to a stereophonic source (1), a speaker (5D, 5G) which restores for each channel the medium and high frequency sound, and comprising, common to-both channels, a device for restoring the low frequency acoustic signals, characterized in that the device for restoring the low frequency acoustic signals comprises an acoustic box having two enclosures (10D, 10G) which each support at least one speaker (11D, 11G) in such a way that the rear face of each speaker radiates into its enclosure whereas the front face of each speaker radiates into a cavity (15) which is connected to both enclosures and which communicates with the outside through an opening of predetermined dimensions, this cavity and this opening being such that the upper cut-off frequency of the box depends on the volume of the cavity and that the acoustic efficiency of the box depends on the surface of said opening, one speaker of this box being directly connected to the left channel amplifier output and the other speaker being directly connected to the right channel output.
2. A system according to claim 1, characterized in that it comprises means which are adapted to vary said predetermined dimensions.
3. A system according to claim 1 or 2, characterized in that the two enclosures (10D, 10G) are identical and are placed one in front of the other at a predetermined distance in such a way that the speaker(s) of one channel is (are) in front of the speaker(s) or the other channel and that their respective front faces radiate into the cavity (15) constituted by the extension of the walls of both enclosures, perpendicularly to the faces which support the speaker(s), and that an opening of predetermined width is left therein.
4. A system according to claims 2 and 3, characterized in that the two enclosures (10D, 10G) are maintained at a distance one from the other by means of a set of interchangeable wedges (12) of variable thickness so as to vary the width (x) of the opening.
5. A system according to claims 2 and 3, characterized in that the two enclosures (10D, 10G) are held one facing the other by means of adjustable jacks.
6. A system according to claim 1 or 2, characterized in that the two enclosures (10D, 10G) are identical and are placed side by side so as to have a common wall and so that the speakers (11 D, 11G) are located in a common plane with their front face radiating into the cavity (15) formed on the one hand by the extension of the walls which are not common to the enclosures perpendicularly to the speaker support faces, and on the other hand by a wall which is parallel to the plane of these speaker support faces, this latter wall containing an opening of predetermined dimensions.
7. A system according to one of claims 1 to 6, characterized in that the two enclosures (10D, 10G) are of the counter-resonance type.
8. A system according to any one of the preceding claims, characterized in that the speaker(s) of each enclosure is (are) directly connected to the amplifier output of the corresponding channel.
EP80400180A 1979-02-23 1980-02-05 Three-channel acoustic system Expired EP0015186B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7904661A FR2450019A1 (en) 1979-02-23 1979-02-23 LOW FREQUENCY SUBWOOFER, ESPECIALLY FOR A THREE-PHONE ACOUSTIC SYSTEM
FR7904661 1979-02-23

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EP0015186A1 EP0015186A1 (en) 1980-09-03
EP0015186B1 true EP0015186B1 (en) 1985-07-24

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EP (1) EP0015186B1 (en)
DE (1) DE3070893D1 (en)
FR (1) FR2450019A1 (en)

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Also Published As

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EP0015186A1 (en) 1980-09-03
DE3070893D1 (en) 1985-08-29
FR2450019B1 (en) 1982-04-02
US4326099A (en) 1982-04-20
FR2450019A1 (en) 1980-09-19

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