EP0101031A2 - Arrangement for sound sources avoiding acoustic short circuits in loudspeakers - Google Patents
Arrangement for sound sources avoiding acoustic short circuits in loudspeakers Download PDFInfo
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- EP0101031A2 EP0101031A2 EP83107746A EP83107746A EP0101031A2 EP 0101031 A2 EP0101031 A2 EP 0101031A2 EP 83107746 A EP83107746 A EP 83107746A EP 83107746 A EP83107746 A EP 83107746A EP 0101031 A2 EP0101031 A2 EP 0101031A2
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- loudspeakers
- air
- loudspeaker
- resonance
- sound
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- 230000001747 exhibiting effect Effects 0.000 abstract 1
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- 238000004519 manufacturing process Methods 0.000 description 3
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
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Classifications
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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
- H04R1/2853—Enclosures comprising vibrating or resonating arrangements using an acoustic labyrinth or a transmission line
- H04R1/2857—Enclosures comprising vibrating or resonating arrangements using an acoustic labyrinth or a transmission line for loudspeaker transducers
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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
- H04R1/26—Spatial arrangements of separate transducers responsive to two or more frequency ranges
Definitions
- the invention relates to a device by means of which the mutual cancellation of antiphase sound waves, which are generated by the front and rear membrane surfaces of loudspeakers, can be prevented.
- the device can primarily be used with woofers.
- baffles formed by a rigid, flat plate, the edge of which is outside a circle around the axis of the loudspeaker with the Radius ⁇ / 4, where A is the wavelength of the lowest frequency to be emitted.
- the smallest linear dimension of the baffle is 5.7 to 4.3 meters, so that such baffles cannot be used in practice.
- woofers are operated with loudspeakers that are softly suspended and have a small diaphragm diameter with a large impact. They are also closed in such a way that the acoustic short circuit disappears and the box dimensions are relatively small.
- the lower limit frequency of such sound emitters depends primarily on the housing volume down. Such a housing must be well sealed and manufactured in first-class carpentry work with rigid walls.
- the sound emitter used should have a small diameter in order to achieve a low lower cut-off frequency, as a result of which the load capacity is greatly influenced.
- the characteristic features of an average quality studio control sound source are as follows: lower cut-off frequency 35 Hz, load capacity 40 VA, volume 0.15 m 3 .
- the design of the reflex housing is more complicated than that of a closed housing; however, its efficiency is generally better.
- Known good quality bass radiators are the various embodiments with exponential funnel coupling, which are of particularly good quality - their efficiency is an order of magnitude better than that of radiators with a closed housing - because they not only eliminate the acoustic short circuit, but also because can solve optimal coupling between the speaker and the external sound space.
- Their dimensions are simpler with conical funnels: however, these have a self-resonance that can be remedied by using sound-absorbing material, but this reduces the efficiency.
- Sound emitters with a lower cut-off frequency and a feed path of length A or ⁇ / 4 are also known (A means the wavelength which belongs to the self-resonance frequency of the loudspeaker used).
- A means the wavelength which belongs to the self-resonance frequency of the loudspeaker used.
- these can transform an excessively low load impedance on the loudspeaker membrane into the area of the self-resonance frequency or they cause the increase in the transmission characteristics present here to disappear by canceling signals of the opposite phase.
- the feed path of length A also adds the signals of the two halves of the membrane in phase at half the self-resonance frequency.
- the self-resonances and other internal reflections are also remedied here by installing sound-absorbing material, but this reduces the efficiency.
- This efficiency is lower than that of the baffle, but is better than that of the closed reflex housing.
- the volume of the feed path with the length ⁇ / 4 is approximately the same as that of the reflex housing in the case of the same load capacity; the construction is complicated, but much smaller and simpler than that of the funnel designs.
- the volume of the feed path with a length ⁇ is four times - but is still smaller than that of the funnel designs.
- a very young special solution is described in DE-A-29 34 473.
- a feed line is used here for each frequency to be broadcast, which is referred to as a balanced resona goal works.
- the spectrum image of the electrical signals of the closed generator that is to say the timbre, is shaped with the aid of the resonance. This spotlight can therefore only be used for special electronic instruments, but not for linear transmission.
- a starting point of the invention is that the undesirable resonances of the feed paths%, ⁇ / 4 are not dampened by built-in sound-absorbing materials.
- several loudspeakers of different self-resonance frequencies, and accordingly several feed paths of different lengths, are used simultaneously. Even transmission is ensured by an even distribution of the resonance points.
- the dimensions of the feed paths can thus be independent of the self-resonance frequency of the loudspeakers and the length of the shortest feed path is determined by the requirement to eliminate the acoustic short circuit.
- the lengths of the other feed paths are chosen such that the fundamental resonances of the feed path resonances are at one Area larger than a frequency interval with a ratio of 3: 2 are evenly distributed.
- At least three loudspeakers are provided in a device according to the invention for 5-beam radiators, in particular for emitting deep hairdryers with a characteristic of uniform frequency transmission and good efficiency.
- Each of the loudspeakers is connected to a rigid wall having a closed outer surface in such a way that one end of the air column bounded by the outer surface is closed off by the membrane of the loudspeakers, whereas the other end of the air columns is connected to the outer air space.
- the longitudinal dimensions of the outer surface are chosen such that the shortest air connection between the front and the rear of the respective membrane is not shorter than 1/3 of the wavelength of the sound wave to be emitted with the lowest frequency, the length of the air columns from each other and from half and a quarter of the wavelength of the self-resonance of the connected speakers are different and the inputs of the speakers are connected to a low-impedance generator.
- the embodiments characteristic of the invention are technologically very simple.
- PVC, paper or asbestos cement pipes with the final diameter of the conical membrane of the speakers used are cut to the required lengths (in the case of a cut-off frequency of 30 Hz to 2 to 3 meters) and the speakers are attached at one end by screws . This eliminates the time-consuming and demanding carpentry work.
- the device according to the invention with good efficiency is suitable for transmitting such low frequencies (16 Hz) that cannot be transmitted with the help of baffle, reflex housing and funnel.
- the volume of the device according to the invention larger than the volume of a closed reflex housing, but smaller than that of a baffle or an exponential funnel.
- the invention is suitable for realizing lower limit frequencies as in the known feed paths with a length of ⁇ or A / 4, however their efficiency is better. With the same lower limit frequency and load capacity, their volume is smaller than that of the length A feed path and is generally somewhat larger than that of the length ⁇ / 4 feed path.
- the feed paths of length ⁇ or ⁇ / 4 can also be produced in the described simple form and technology. In this case, the manufacturing costs correspond approximately to the manufacturing costs of the radiator according to the invention
- the manufacturing costs of the other known sound radiators are higher than that of the sound radiator according to the invention (in this comparison, of course, the same lower cut-off frequency and the same load capacity are required).
- An embodiment according to the German publication already mentioned is externally similar to the device according to the invention, since a separate loudspeaker is also used there for each resonance tube (feed path).
- the dimensions of the feed routes according to the invention are different. According to the invention, shorter feed paths are present in any case than in the known embodiment (assuming the same lower cut-off frequency).
- the known embodiment does not require the inputs of the loudspeakers to be connected to a low-impedance generator .
- the bandwidth of the food resonance ie the characteristic of the frequency transmission, may differ from the characteristic of the frequency transmission according to the invention.
- the known construction in general cannot be used for broadband transmission either, but only for amplifying the resonance of the radiation from certain frequencies, for transforming tones with electric organs, configured according to the given timbres.
- the invention consists of a plurality - at least three - speakers 1 having sound emitters, the conical membrane 3 of each speaker 1 is connected to a rigid closed jacket-shaped or tubular wall 2 such that the membrane 3 of the speaker 1 one end of the the circumferential surface of the air column 4 is completed, while the other end of the air column 4 is connected to the outer air space.
- the lateral surface and the air column 4 enclosed therein are referred to here as the "feed path”.
- the German publication mentioned above refers to this construction as a "resonance pipe”.
- the front and back of the loudspeaker membrane are separated from each other by the jacket surfaces. Their lengths should be chosen so that the shortest, through the air, connecting the two sides of the membrane Link (see the dashed line in Fig. 1) should not be shorter than a third of the wavelength of the cut-off frequency to be transmitted for any loudspeaker, and that the lengths of the air columns differ from each other.
- the loudspeakers are to be driven with a generator of low impedance.
- the air columns can be bent straight or arbitrarily, turned, bent with their sections adjoining one another and the like (see FIG. 2).
- the lower limit frequency of the sound system is decisively determined by the shortest feed path (it is less influenced by the longer feed paths). If the two ends of the feed paths are close to each other, the shortest air connection between the two sides of the membrane is reduced compared to such a connection with a straight feed path. Through these feed paths, however, the volume velocities become in phase at their own self-resonance frequency, so that a higher degree of efficiency is achieved. It is obvious that the longest feed paths should be designed in this way in a sound emitter system.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
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- Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
- Circuit For Audible Band Transducer (AREA)
Abstract
Description
Gegenstand der Erfindung ist eine Vorrichtung, mit deren Hilfe die gegenseitige Auslöschung von gegenphasigen Schallwellen, die durch die vordere und die hintere Membranfläche von Lautsprechern erzeugt sind, verhindert werden können. Die Vorrichtung kann in erster Linie bei Tieftonstrahlern verwendet werden.The invention relates to a device by means of which the mutual cancellation of antiphase sound waves, which are generated by the front and rear membrane surfaces of loudspeakers, can be prevented. The device can primarily be used with woofers.
Eine der wichtigsten Aufgaben der Schallstrahler ist die Beseitigung der akustischen Kurzschlußerscheinungen der angeschlossenen elektroakustischen Wandler (Lautsprecher) Eine klassische Lösung hierfür besteht in der Anwendung einer durch eine starre ebene Platte gebildeten Schallwand, deren Rand sich außerhalb eines um die Achse des Lautsprechers gelegten Kreises mit dem Radius λ /4 befindet, wobei A die Wellenlänge der tiefsten auszustrahlenden Frequenz bedeutet. Im Falle einer für Tieftonlautsprecher unerläßlichen unteren Grenzfrequenz von 30 bis 40 Hz beträgt die kleinste Lineare Abmessung der Schallwand 5,7 bis 4,3 Meter, so daß solche Schallwände in der Praxis nicht verwendbar sind.One of the most important tasks of the sound emitters is the elimination of the acoustic short-circuit phenomena of the connected electroacoustic transducers (loudspeakers) .A classic solution for this is the use of a baffle formed by a rigid, flat plate, the edge of which is outside a circle around the axis of the loudspeaker with the Radius λ / 4, where A is the wavelength of the lowest frequency to be emitted. In the case of a lower cut-off frequency of 30 to 40 H z, which is essential for woofers, the smallest linear dimension of the baffle is 5.7 to 4.3 meters, so that such baffles cannot be used in practice.
Die meisten modernen Tieftonstrahler werden mit Lautsprechern betrieben, die weich aufgehängt sind und einen kleinen Membrandurchmesser mit großem Stoß aufweisen. Sie sind außerdem geschlossen, derart, daß der akustische Kurzschluß verschwindet und verhältnismäßig kleine Boxenabmessungen vorliegen. Die untere Grenzfrequenz solcher Schallstrahler hängt in erster Linie von dem Gehäusevolumen ab. Solch ein Gehäuse muß gut abgedichtet und in erstklassiger Tischlerarbeit mit steifen Wänden gefertigt werden.Most modern woofers are operated with loudspeakers that are softly suspended and have a small diaphragm diameter with a large impact. They are also closed in such a way that the acoustic short circuit disappears and the box dimensions are relatively small. The lower limit frequency of such sound emitters depends primarily on the housing volume down. Such a housing must be well sealed and manufactured in first-class carpentry work with rigid walls.
Infolge des Prinzips der Betriebsart soll der angewendete Schallstrahler - um eine niedrige untere Grenzfrequenz zu erreichen - einen kleinen Durchmesser aufweisen, wodurch die Belastbarkeit stark beeinflußt wird. Die charakteristischen Merkmale eines Studio-Kontroll-Schallstrahlers durchschnittlicher Qualität sind die folgenden: untere Grenzfrequenz 35 Hz, Belastbarkeit 40 VA, Volumen 0,15 m3. Bei gleichbleibender unterer Grenzfrequenz und gleichbleibenden Gehäuseabmessungen kann eine größere Belastbarkeit nur mit äußerst kostspieligen Lautsprechern erreicht werden. Der Lautsprecher ist in einem geschlossenen Raum außer durch die strahlende Impedanz auch durch die Impedanz des Innenraums des Gehäuses belastet. Sein Wirkungsgrad ist also schlechter als der eines in einer Schallwand eingebauten Lautsprechers.As a result of the principle of the operating mode, the sound emitter used should have a small diameter in order to achieve a low lower cut-off frequency, as a result of which the load capacity is greatly influenced. The characteristic features of an average quality studio control sound source are as follows: lower cut-off frequency 35 Hz, load capacity 40 VA, volume 0.15 m 3 . With a constant lower cut-off frequency and constant housing dimensions, greater resilience can only be achieved with extremely expensive loudspeakers. In a closed room, the loudspeaker is loaded not only by the radiating impedance but also by the impedance of the interior of the housing. Its efficiency is therefore worse than that of a loudspeaker built into a baffle.
Um die untere Grenzfrequenz zu vermindern, werden in manchen Fällen sog. Baßreflexgehäuse verwendet. Die Literatur hat aber nachgewiesen (Bild- und Tontechnik, 1976, Nr 3) daß dies nur mit der Vergrößerung des Gehäuses realisiert werden kann und zwar mit einem Lautsprecher niedriger Selbstresonanz und großen Tonstoßes.So-called bass reflex housings are used in some cases to reduce the lower limit frequency. However, the literature has shown (picture and sound technology, 1976, No. 3) that this can only be achieved by enlarging the housing, using a loudspeaker with low self-resonance and a large sound impact.
Die Ausbildung des Reflexgehäuses ist komplizierter als die eines geschlossenen Gehäuses; sein Wirkungsgrad ist aber im allgemeinen besser.The design of the reflex housing is more complicated than that of a closed housing; however, its efficiency is generally better.
Bekannte Tieftonstrahler guter Qualität sind die verschiedenen Ausführungsformen mit Exponentialtrichter-Kopplung, die von besonders guter Qualität sind - ihr Wirkungsgrad ist um eine Größenordnung besser als der von Strahlern mit geschlossenem Gehäuse - und zwar deshalb, weil sie außer der Beseitigung des akustischen Kurzschlusses die optimale Kopplung zwischen dem Lautsprecher und dem äußeren Schallraum lösen können. Ihre Abmessungen sind einfacher mit konischen Trichtern: diese weisen aber eine Selbstresonanz auf, die durch Anwendung von schalldämpfendem Material behoben werden kann, wodurch aber der Wirkungsgrad vermindert wird.Known good quality bass radiators are the various embodiments with exponential funnel coupling, which are of particularly good quality - their efficiency is an order of magnitude better than that of radiators with a closed housing - because they not only eliminate the acoustic short circuit, but also because can solve optimal coupling between the speaker and the external sound space. Their dimensions are simpler with conical funnels: however, these have a self-resonance that can be remedied by using sound-absorbing material, but this reduces the efficiency.
Schallstrahler tiefer Grenzfrequenz mit einem Speiseweg der Länge A bzw. λ/4 sind ebenfalls bekannt ( A bedeutet die Wellenlänge, die zur Selbstresonanzfrequenz des verwendeten Lautsprechers gehört). Diese können außer der Beseitigung des akustischen Kurzschlusses eine zu tiefe Belastungsimpedanz auf der Lautsprechermembran in den Bereich der Selbstresonanzfrquenz transformieren oder sie führen das Verschwinden des hier anwesenden Anhebens in der Obertragungscharakteristik durch das Auslöschen von Signalen entgegengesetzter Phase durch. Der Speiseweg der Länge A addiert außerdem bei der Hälfte der Selbstresonanzfrequenz die Signale der beiden Hälften der Membran phasenrichtig. Somit wird - alleinstehend bei den bekannten Lösungen - unterhalb der Selbstresonanzfrequenz wirkungsvoll gestrahlt. Die Selbstresonanzen und sonstigen inneren Reflexionen werden auch hier durch Einbau von aschalldämpfendem Material behoben, wodurch aber der Wirkungsgrad vermindert wird. Dieser Wirkungsgrad liegt unter dem der Schallwand , ist aber besser als der der geschlossenen Reflexgehäuse. Das Volumen des Speiseweges mit der Länge λ/4 ist im Falle gleicher Belastbarkeit ungefähr gleich zu dem der Reflexgehäuse; die Konstruktion ist zwar kompliziert, jedoch wesentlich kleiner und einfacher als die der Trichterausführungsformen. Das Volumen des Speiseweges mit einer Länge λ beträgt das vierfache - ist aber noch immer kleiner als das der Trichterausführungsformen.Sound emitters with a lower cut-off frequency and a feed path of length A or λ / 4 are also known (A means the wavelength which belongs to the self-resonance frequency of the loudspeaker used). In addition to the elimination of the acoustic short circuit, these can transform an excessively low load impedance on the loudspeaker membrane into the area of the self-resonance frequency or they cause the increase in the transmission characteristics present here to disappear by canceling signals of the opposite phase. The feed path of length A also adds the signals of the two halves of the membrane in phase at half the self-resonance frequency. Thus, alone in the known solutions, radiation is effective below the self-resonance frequency. The self-resonances and other internal reflections are also remedied here by installing sound-absorbing material, but this reduces the efficiency. This efficiency is lower than that of the baffle, but is better than that of the closed reflex housing. The volume of the feed path with the length λ / 4 is approximately the same as that of the reflex housing in the case of the same load capacity; the construction is complicated, but much smaller and simpler than that of the funnel designs. The volume of the feed path with a length λ is four times - but is still smaller than that of the funnel designs.
Eine ganz junge spezielle Lösung wird in der DE-A-29 34 473 beschrieben. Es wird hier für jede auszustrahlende Frequenz eine Speiseleitung verwendet, die als abgeglichenr Resonator wirkt. Außer daß diese den akustischen Kurzschluß beheben, wird - nach der Beschreibung - mit Hilfe der Resonanz das Spektrumbild der elektrischen Signale des geschlossenen Generators, d.h. die Klangfarbe geformt. Dieser Strahler ist demnach nur für spezielle elektronische Instrumente verwendbar, jedoch nicht für eine lineare Obertragung.A very young special solution is described in DE-A-29 34 473. A feed line is used here for each frequency to be broadcast, which is referred to as a balanced resona goal works. In addition to correcting the acoustic short circuit, the spectrum image of the electrical signals of the closed generator, that is to say the timbre, is shaped with the aid of the resonance. This spotlight can therefore only be used for special electronic instruments, but not for linear transmission.
Ein Ausgangspunkt der Erfindung besteht darin, daß die nicht erwünschten Resonanzen der Speisewege % , λ/4 nicht durch eingebaute schalldämpfende Materialien gedämpft werden. Demgegenüber werden mehrere Lautsprecher unterschiedlicher Selbstresonanzfrequenz, und dementsprechend mehrere Speisewege unterschiedlicher Länge gleichzeitig verwendet. Durch eine gleichmäßige Verteilung der Resonanzpunkte wird eine gleichmäßige Übertragung gesichert.A starting point of the invention is that the undesirable resonances of the feed paths%, λ / 4 are not dampened by built-in sound-absorbing materials. In contrast, several loudspeakers of different self-resonance frequencies, and accordingly several feed paths of different lengths, are used simultaneously. Even transmission is ensured by an even distribution of the resonance points.
Im Verlauf von Versuchen wurde klar, daß eine die Selbstresonanz dämpfende Wirkung der Speisewege kein wirksamer Effekt ist. Diese Tatsache folgt prinzipiell auch daraus, daß die Lautsprecherresonanz durch Lautsprecher niedriger Impedanz und durch die Antriebsgeneratoren unabhängig von dem Speiseweg - infolge des elektrischen Antriebskreises niedriger Impedanz - genügend gedämpft wird. Diese Erscheinung kann die Resonanzen der Speisewege weniger dämpfen (da diese wesentlich mehr Energie zum Speichern imstande sind), kann jedoch die Resonanzbandbreite derart vergrößern, daß durch einige Speisewege entsprechend verteilter Resonanzfrequenz eine gleichmäßige Frequenzübertragungscharakteristik erreicht werden kann. Somit können die Abmessungen der Speisewege von der Selbstresonanzfrequenz der Lautsprecher unabhängig sein und wird die Länge des kürzesten Speiseweges durch die Forderung der Beseitigung des akustischen Kurzschlusses bestimmt. Die Längen der anderen Speisewege werden nach Erfahrung derart gewählt, daß die Grundresonanzen der Speisewegresonanzen auf einen Bereich größer als ein Frequenzintervall mit einem Verhältiis von 3:2 gleichmäßig verteilt werden.In the course of experiments it became clear that a self-resonance-damping effect of the food passages is not an effective effect. In principle, this fact also follows from the fact that the loudspeaker resonance is sufficiently attenuated by loudspeakers of low impedance and by the drive generators, regardless of the feed path, as a result of the electrical drive circuit of low impedance. This phenomenon can dampen the resonances of the feed paths less (since they are able to store much more energy), but can increase the resonance bandwidth in such a way that a uniform frequency transmission characteristic can be achieved by some feed paths according to the distributed resonance frequency. The dimensions of the feed paths can thus be independent of the self-resonance frequency of the loudspeakers and the length of the shortest feed path is determined by the requirement to eliminate the acoustic short circuit. Experience has shown that the lengths of the other feed paths are chosen such that the fundamental resonances of the feed path resonances are at one Area larger than a frequency interval with a ratio of 3: 2 are evenly distributed.
)emgemäß sind bei einer erfindungsgemäßen Vorrichtung für 5challstrahler insbesondere zur Ausstrahlung von tiefen fönen mit einer Charakteristik gleichmäßiger Frequenzübertragung und gutem Wirkungsgrad wenigstens drei Lautsprecher, jedoch weniger Lautsprecher als die Anzahl der abzustrahlenden Töne unterschiedlicher Frequenzen vorgesehen. Jeder der Lautsprecher ist an je eine eine geschlossene Mantelfläche aufweisende starre Wand derart angeschlossen, daß durch die Membran der Lautsprecher das eine Ende der durch die Mantelfläche umgrenzten Luftsäule abgeschlossen ist, wohingegen das andere Ende der Luftsäulen mit dem äußeren Luftraum in Verbindung steht. Die Längsabmessungen der Mantelfläche sind derart gewählt, daß die kürzeste durch die Luft verlaufende Verbindungsstrecke zwischen der Vorderseite und der Hinterseite der jeweiligen Membran nicht kürzer als 1/3 der Wellenlänge der auszustrahlenden Schallwelle mit der untersten Frequenz sind, wobei die Länge der Luftsäulen voneinander und von der halben und viertel Wellenlänge der Selbstresonanz der angeschlossenen Lautsprecher verschieden sind und die Eingänge der Lautsprecher an einen Generator niedriger Impedanz angeschlossen sind.According to the invention, at least three loudspeakers, but fewer loudspeakers than the number of tones to be emitted of different frequencies, are provided in a device according to the invention for 5-beam radiators, in particular for emitting deep hairdryers with a characteristic of uniform frequency transmission and good efficiency. Each of the loudspeakers is connected to a rigid wall having a closed outer surface in such a way that one end of the air column bounded by the outer surface is closed off by the membrane of the loudspeakers, whereas the other end of the air columns is connected to the outer air space. The longitudinal dimensions of the outer surface are chosen such that the shortest air connection between the front and the rear of the respective membrane is not shorter than 1/3 of the wavelength of the sound wave to be emitted with the lowest frequency, the length of the air columns from each other and from half and a quarter of the wavelength of the self-resonance of the connected speakers are different and the inputs of the speakers are connected to a low-impedance generator.
Die für die Erfindung charakteristischen Ausführungsformen sind technologisch sehr einfach aufgebaut. Als Fertigprodukt erhältliche PVC-, Papier- oder Asbestzementrohre mit dem Enddurchmesser der kegelförmigen Membran der verwendeten Lautsprecher werden auf die erforderlichen Längen (im Falle einer Grenzfrequenz von 30 Hz auf 2 bis 3 Meter) geschnitten und die Lautsprecher werden an dem einen Ende durch Schrauben befestigt. Somit entfällt die aufwendige und anspruchsvolle Tischlerarbeit.The embodiments characteristic of the invention are technologically very simple. As a finished product, PVC, paper or asbestos cement pipes with the final diameter of the conical membrane of the speakers used are cut to the required lengths (in the case of a cut-off frequency of 30 Hz to 2 to 3 meters) and the speakers are attached at one end by screws . This eliminates the time-consuming and demanding carpentry work.
Vergleicht man die Eigenschaften der erfindungsgemäßen Vorrichtung mit denen der bekannten Schallstrahler, so wird gleich klar, daß die erfindungsgemäße Vorrichtung mit gutem Wirkungsgrad zur übertragung solcher tiefen Frequenzen (16 Hz) geeignet ist, die mit Hilfe von Schallwand, Reflexgehäuse und Trichter nicht übertragen werden können.'Unter Voraussetzung gleicher unterer Grenzfrequenz und Belastbarkeit ist das Volumen der erfindungsgemäßen Vorrichtung größer als das Volumen eines geschlossenen Reflexgehäuses, ist aber kleiner als das einer Schallwand bzw. eines exponentiellen Trichters. Die Erfindung ist geeignet, untere Grenzfrequenzen wie bei den bekannten Speisewegen einer Länge von λ bzw. A/4 zu realisieren, jedoch ist ihr Wirkungsgrad besser. Bei einer gleichen unteren Grenzfrequenz und Belastbarkeit ist ihr Volumen kleiner als das des Speiseweges der Länge A und ist im allgemeinen ein wenig größer als das des Speiseweges mit der Länge λ/4. Die Speisewege der Länge λ bzw. λ/4 können ebenfalls in der geschilderten, einfachen Form und Technologie hergestellt werden. In diesem Falle stimmen die Herstellungskosten annähernd mit den Herstellungskosten des erfindungsgemäßen Strahlers übereinaIf one compares the properties of the device according to the invention with those of the known sound emitters, it becomes equally clear that the device according to the invention with good efficiency is suitable for transmitting such low frequencies (16 Hz) that cannot be transmitted with the help of baffle, reflex housing and funnel. 'Assuming the same lower limit frequency and load capacity, the volume of the device according to the invention larger than the volume of a closed reflex housing, but smaller than that of a baffle or an exponential funnel. The invention is suitable for realizing lower limit frequencies as in the known feed paths with a length of λ or A / 4, however their efficiency is better. With the same lower limit frequency and load capacity, their volume is smaller than that of the length A feed path and is generally somewhat larger than that of the length λ / 4 feed path. The feed paths of length λ or λ / 4 can also be produced in the described simple form and technology. In this case, the manufacturing costs correspond approximately to the manufacturing costs of the radiator according to the invention
Die Herstellungskosten der anderen bekannten Schallstrahler sind jedoch höher als die des Schallstrahlers gemäß der Erfindung (bei diesem Vergleich ist natürlich eine gleiche untere Grenzfrequenz und gleiche Belastbarkeit voraussgesetzt). Ein Ausführungsbeispiel nach der bereits erwähnten deutschen Druckschrift ist äußerlich ähnlich zu der erfindungsgemäßen Vorrichtung, da auch dort für ein jedes Resonanzrohr (Speiseweg) ein gesonderter Lautsprecher verwendet wird. Jedoch sind die Abmessungen.der'Speisewege gemäß der Erfindung anders. Gemäß der Erfindung sind in jedem Falle kürzere Speisewege als bei der bekannten Ausführungsform vorhanden (gleiche untere Grenzfrequenz vorausgesetzt) weiter ist - im Gegensatz zu der erfindungsgemäßen Ausführungsform - bei der bekannten Ausführungsform nicht vorgeschrieben, daß die Eingänge der Lautsprecher an einen Generator tiefer Impedanz angeschlossen sind. Somit (ann die Bandbreite der Speisewgeresonanzen, d.h. die Charakteristik der Frequenzübertragung, beliebig von der Charakteristik der Frequenzübertragung gemäß der Erfindung abweichen. Die bekannte Konstruktion kann auch im allgemeinen nicht für eine Breitbandübertragung, sondern nur zur Resonanzverstärkung der Strahlung von bestimmten Frequenzen, zur Umformung von Tönen bei elektrischen Orgeln, projektiert entsprechend der gegebenen Klangfarben, verwendet werden.However, the manufacturing costs of the other known sound radiators are higher than that of the sound radiator according to the invention (in this comparison, of course, the same lower cut-off frequency and the same load capacity are required). An embodiment according to the German publication already mentioned is externally similar to the device according to the invention, since a separate loudspeaker is also used there for each resonance tube (feed path). However, the dimensions of the feed routes according to the invention are different. According to the invention, shorter feed paths are present in any case than in the known embodiment (assuming the same lower cut-off frequency). In contrast to the embodiment according to the invention, the known embodiment does not require the inputs of the loudspeakers to be connected to a low-impedance generator . Consequently (The bandwidth of the food resonance, ie the characteristic of the frequency transmission, may differ from the characteristic of the frequency transmission according to the invention. The known construction in general cannot be used for broadband transmission either, but only for amplifying the resonance of the radiation from certain frequencies, for transforming tones with electric organs, configured according to the given timbres.
Die Erfindung wird anhand der beiliegenden Zeichnungen näher erörtert.
- Fig. 1 stellt schematisch den Schallstrahler dar, und in
- Fig. 2 sind unterschiedliche Gestaltungen der Luftsäulen (Speisewege), ebenfalls schematisch, gezeigt.
- Fig. 1 shows schematically the sound emitter, and in
- Fig. 2 different designs of the air columns (feed routes), also shown schematically.
Die Erfindung besteht aus einem mehrere - mindestens drei - Lautsprecher 1 aufweisenden Schallstrahler, wobei die kegelförmige Membran 3 jedes Lautsprechers 1 an eine starre geschlossene mantelförmige bzw. rohrförmige Wand 2 derart angeschlossen ist, daß von der Membran 3 des Lautsprechers 1 das eine Ende der durch die Mantelfläche umgrenzten Luftsäule 4 abgeschlossen wird, während das andere Ende der Luftsäule 4 mit dem äußeren Luftraum verbunden ist. Die Mantelfläche und die darin eingeschlossene Luftsäule 4 werden hier mit "Speiseweg" bezeichnet. Die oben bereits erwähnte deutsche Druckschrift bezeichnet diese Konstruktion als "Resonanzrohr".The invention consists of a plurality - at least three - speakers 1 having sound emitters, the
Durch die Mantelflächen werden die Vorderseite und Hinterseite der Lautsprechermembran voneinander abgeteilt. Ihre Längen sollen derart gewählt werden, daß die kürzeste, die beiden Membranseiten verbindende durch die Luft verlaufende Verbindungsstrecke (Siehe in Fig. 1 die gestrichelt eingezeichnete Verbindungsstrecke) bei keinem Lautsprecher kürzer sein soll als ein Drittel der Wellenlänge der zu übertragenen Grenzfrequenz, und daß die Längen der Luftsäulen voneinander abweichen. Die Lautsprecher sollen - um die Selbstresonanz zu dämpfen - mit einem Generator kleiner Impedanz angetrieben werden. Die Luftsäulen können gerade oder beliebig gebogen, gedreht, mit ihren Abschnitten aneinandergrenzend geknickt und dergleichen mehr ausgebildet werden (siehe Fig. 2).The front and back of the loudspeaker membrane are separated from each other by the jacket surfaces. Their lengths should be chosen so that the shortest, through the air, connecting the two sides of the membrane Link (see the dashed line in Fig. 1) should not be shorter than a third of the wavelength of the cut-off frequency to be transmitted for any loudspeaker, and that the lengths of the air columns differ from each other. In order to dampen the self-resonance, the loudspeakers are to be driven with a generator of low impedance. The air columns can be bent straight or arbitrarily, turned, bent with their sections adjoining one another and the like (see FIG. 2).
Bei Ausführungsformen, bei denen die beiden Enden der Speisewege weit voneinander wegliegen (z.B. bei einer Luftsäule mit geradliniger Achse) wird die untere Grenzfrequenz des Schallsystems entscheidend durch den kürzesten Speiseweg bestimmt (durch die längeren Speisewege wird sie weniger beeinflußt). Wenn die beiden Enden der_Speisewege nahe beieinander liegen, so vermindert sich die kürzeste durch die Luft verlaufende Verbindungsstrecke zwischen den beiden Seiten der Membran im Vergleich mit einer solchen Verbindungsstrecke bei einem geradlinigen Speiseweg. Durch diese Speisewege werden aber die Volumengeschwindigkeiten bei ihrer eigenen Selbstresonanzfreqenz phasengleich, so daß dadurch ein höherer Wirkungsgrad erreicht ist. Es liegt auf der Hand, daß bei einem Schallstrahlersystem die längsten Speisewege derart ausgebildet werden sollen.In embodiments in which the two ends of the feed paths are far apart (e.g. in the case of an air column with a straight axis), the lower limit frequency of the sound system is decisively determined by the shortest feed path (it is less influenced by the longer feed paths). If the two ends of the feed paths are close to each other, the shortest air connection between the two sides of the membrane is reduced compared to such a connection with a straight feed path. Through these feed paths, however, the volume velocities become in phase at their own self-resonance frequency, so that a higher degree of efficiency is achieved. It is obvious that the longest feed paths should be designed in this way in a sound emitter system.
Claims (3)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| HU251482A HU186101B (en) | 1982-08-05 | 1982-08-05 | Sound radiator without effect of acoustic short circuit of the loadspeakers |
| HU251482 | 1982-08-05 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0101031A2 true EP0101031A2 (en) | 1984-02-22 |
| EP0101031A3 EP0101031A3 (en) | 1986-04-09 |
Family
ID=10959778
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP83107746A Withdrawn EP0101031A3 (en) | 1982-08-05 | 1983-08-05 | Arrangement for sound sources avoiding acoustic short circuits in loudspeakers |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0101031A3 (en) |
| HU (1) | HU186101B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5170435A (en) * | 1990-06-28 | 1992-12-08 | Bose Corporation | Waveguide electroacoustical transducing |
| EP0624045A1 (en) * | 1993-05-06 | 1994-11-09 | Bose Corporation | Frequency selective acoustic waveguide damping |
| DE19601217C1 (en) * | 1996-01-15 | 1997-07-24 | Mark Iv Audio Deutschland Gmbh | Bass reflex box |
| WO2008056258A2 (en) * | 2006-11-10 | 2008-05-15 | Pss Belgium Nv | Loudspeaker system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1912454A (en) * | 1932-03-03 | 1933-06-06 | William H Hutter | Acoustic apparatus |
| US3993162A (en) * | 1975-06-20 | 1976-11-23 | Kenneth Juuti | Acoustic speaker system |
-
1982
- 1982-08-05 HU HU251482A patent/HU186101B/en not_active IP Right Cessation
-
1983
- 1983-08-05 EP EP83107746A patent/EP0101031A3/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1912454A (en) * | 1932-03-03 | 1933-06-06 | William H Hutter | Acoustic apparatus |
| US3993162A (en) * | 1975-06-20 | 1976-11-23 | Kenneth Juuti | Acoustic speaker system |
Non-Patent Citations (3)
| Title |
|---|
| AUDIO, Band 40, Nr. 9, September 1956, Seiten 34-42 und 82-86, New York, US; E.J. JORDAN: "Baffles unbaffled" * |
| FUNKSCHAU, Nr. 9, April 1982, Seiten 69-70, M}nchen, DE; H. SCHAPER: "Akustische Laufzeitleitung" * |
| JOURNAL OF THE AUDIO ENGINEERING SOCIETY, Band 7, Nr. 1, Januar 1959, Seiten 38-46, New York, US; P.W. TAPPAN: "Analysis of a low-frequency loudspeaker system" * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5170435A (en) * | 1990-06-28 | 1992-12-08 | Bose Corporation | Waveguide electroacoustical transducing |
| EP0624045A1 (en) * | 1993-05-06 | 1994-11-09 | Bose Corporation | Frequency selective acoustic waveguide damping |
| US6278789B1 (en) | 1993-05-06 | 2001-08-21 | Bose Corporation | Frequency selective acoustic waveguide damping |
| DE19601217C1 (en) * | 1996-01-15 | 1997-07-24 | Mark Iv Audio Deutschland Gmbh | Bass reflex box |
| WO2008056258A2 (en) * | 2006-11-10 | 2008-05-15 | Pss Belgium Nv | Loudspeaker system |
| WO2008056258A3 (en) * | 2006-11-10 | 2008-07-03 | Pss Belgium Nv | Loudspeaker system |
Also Published As
| Publication number | Publication date |
|---|---|
| HU186101B (en) | 1985-06-28 |
| EP0101031A3 (en) | 1986-04-09 |
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