Device for producing coherent sound waves emitted fictitiously from the same point by a specific geometric assembly of 2 or more loudspeakers.

Abstract

[0024] Sound emission device centered on a virtual point (P). [0025] The invention relates to an omnidirectional sound emission device designed to limit vibrations, resonances and parasitic interference. [0026] This comprises two or more loudspeakers (B) fixed together in such a way that the curvature of their respective membranes is centered on the same common point of convergence (P) in order to obtain a clear sound message faithful to the signal delivered by the source. [0027] The device according to the invention is intended for private sound listening or public broadcasting. [0028] Figure for the abstract: Fig. 2

Description

Title of the invention: Device for producing coherent sound waves emitted fictitiously from the same point by a specific geometric assembly of 2 or more loudspeakers. Technical field of the invention

[0001] The present invention relates to a sound production device allowing the diffusion of a refined, centered and omnidirectional acoustic message. Technological background of the invention

[0002] The principle of operation of this innovative device lies in the geometric configuration adopted fixing the loudspeakers which compose it in such a way that the average curvature of their respective membranes are centered on the same point of convergence. The sound emission thus obtained will respect the specific spherical shape of a natural acoustic wave.

[0003] Almost all commercially available loudspeakers offer closed or semi-open boxes with loudspeakers arranged vertically, horizontally or curved, but their respective emission spheres are not centered on a single point, which creates interference and imprecision of the sound message. In addition, the emission behind the loudspeakers is greatly attenuated or lost, disrupting the natural spherical diffusion of the sound. The emission of the spherical sound wave generated by this new device will offer the listener a very precise and refined sound.

[0004] The most common use of this device will be in the context of a classic stereophonic system consisting of two identical devices (right and left), the listener being able to place himself anywhere in the listening room, but with an ideal placement halfway between the two structures and at a sufficient distance to benefit from the best panoramic (stereophonic) effect.

[0005] All variants are possible in terms of number, positioning and types of transducers, if all the geometric assembly principles as stated in the general description are respected with the obtaining of a frequency-corrected response curve as faithful as possible to the initial signal.

[0006] The sound perceived by the listener is clear, fast, free from interference and parasitic resonance, with a precise stereophonic image where the exact location of each sound emitted or of each musician can be located. This results in non-fatiguing listening with a sound quality that remains constant regardless of the power used within the limits of the prescribed use.

[0007] The industrial production of such a system poses no technical problems and makes it possible to envisage models intended for individuals, economical if mid-range loudspeakers are chosen, and more expensive if high-performance transducers are chosen in the case where a high-end set intended for a demanding clientele is aimed. Furthermore, more ambitious and much more powerful models can equip performance halls (auditoriums, cinemas, dance halls, theaters or even operas for example) which are looking for very high sound quality, by choosing a significantly larger structure comprising a greater number of loudspeakers respecting the configuration described and operating with suitable professional electronic amplification. General description of the invention

[0008] The present invention relates to a sound emission device combining several electrodynamic (or possibly electrostatic) loudspeakers (2 at least, without limit) fixed together in such a way that the curvature of their respective membranes is centered on the same point. They thus participate in the emission of a sound message, in front and behind the membranes (or only in front for certain treble transducers), which would be produced from this single virtual emission point, creating a common omnidirectional concentric wave field, in common phase, in the absence of any casing. It also offers the advantage of not creating any acoustic pressure (as is the case for most musical instruments, and the human voice in particular).

[0009] Whatever the materials they are made of, traditional loudspeakers are the source of resonances (box noises) which harm the sound message emitted by this system.

[0010] In this new device, the inevitable acoustic short circuit created by the proximity of the sound vibrations produced in front and behind the same transducer (loudspeaker) within this innovative device will be easily compensated by the use of an active electronic filter which will make it possible to correct the response curve by reinforcing the bass and extreme bass registers.

[0011] The entire device constitutes a sort of portion of an emitting sphere through which a quasi-spherical sound wave passes, fictitiously emitted by the common central point of the curvatures of the loudspeaker membranes. Description of a preferred embodiment

[0012] The loudspeakers are fixed on a common support to ensure good rigidity of the device. The materials to be used for this are of your choice (non-limiting list): wood, composite, resin, glass, but preference goes to metal whose reliability and stability are no longer in doubt.

[0013] In the example chosen, we exhibit a model with 4 cone speakers (woofers) (mid-bass) of 31cm diameter (Bl, B2, B3, B4) and a ribbon tweeter (treble) (T). The craftsman welded 4 metal discs to fix the 4 woofers (B) edge to edge with the precise angulation which was provided to him previously (133° between each in this specific case) and which is specific to the speakers used, their curvatures being variable according to the models, but must imperatively be centered on the same point (P) common to all the transducers used in the structure. These 4 speakers (B) are powered by a power amplifier.

[0014] The angulation of these support discs between them depends on the average curvature of the membranes (M) which can be determined either by calculation or by the use of a specific measuring bench. The ideal would be to have loudspeaker models ideally suited to this device manufactured with membranes of perfectly spherical shape by a manufacturer.

[0015] The tweeter (T) was fixed in the center of the structure (if possible with its ribbon at the level of the surface where the curvature of the membranes of the mid-bass speakers (B) and its emitting surface (flat metal ribbon) meet) being very limited in size we can neglect its non-curvature and will therefore be centered orthogonally at point (P).

[0016] It is powered by a power amplifier adapted to the tweeters. The treble speaker (T) can also be located in front of the common central point (P), but it will be necessary to adapt the phase of this transducer so that its operation respects the direction of the fictitious displacement of the wave from the common center.

[0017] {0017] Each point on the surface of the membranes of the set of loudspeakers must be theoretically equidistant from point (P). In the case where one (or more) loudspeakers are offset forward or backward relative to the others in the structure, it will be necessary to ensure that the concavity of its membrane is centered on the same point of convergence (P). Each point on the surface of its membrane must therefore also be theoretically equidistant from (P). It will also be essential to correct the time shift of acoustic emission by a correction on the active filter.

[0018] [Fig.l] shows the woofers (Bx) and (By) placed edge to edge with the predetermined angulation allowing the alignment of their respective membranes on the same portion of sphere. Thus the two woofers shown and the tweeter (T) emit from their respective centers a common acoustic wave centered on the common convergence point (P). The straight lines (Pa), (Pb) and (Pc), immaterial, indicate the axial direction of emission of each of the loudspeakers.

[0019] [Fig.2] shows the whole of this model with 5 loudspeakers (4 loudspeakers mid-bass (Bl, B2, B3, B4) and 1 treble speaker (T). This figure is a 2-dimensional representation, therefore imperfect, of this system which exists in 3 dimensions because the 5 loudspeakers that constitute it are oriented in such a way that their respective central emission axes all converge towards point (P).

[0020] For a perfect understanding of this device, it must be considered that, apart from the treble speaker, [Fig.l] represents a section along the lines (EH), (FK), (GJ) and (LI) indicated in [Fig.2].

[0021] The system described therefore works with 2 channels (mid-bass and treble) but it is possible to create models with 3 or more channels. The active filter also makes it possible to supply the transducers with the frequency bands assigned to them. In this example the cut-off frequency (frequency of connection of the bass / treble registers) is approximately 2000Hz, the mid-bass register ranging from 20Hz to 2000Hz for the 4 woofers (B), the treble register ranging from 2KHz to 20KHz for the ribbon tweeter (T) (with an overlap of the two registers around 2KHz).

[0022] The active filter also allows the response curve to be corrected by reinforcing the bass and extreme bass registers, essentially below 200Hz (+10 to 15 dB applied to 40 Hz with the low-pass filter and a slope of 12dB per octave) and to make up for the advance or delay (or time delay) of the sound impulse emitted by the tweeter (T) compared to the woofers (B) so that there is perfect temporal coherence of the sound message.

[0023] The whole may be supported by a foot or any other system, which may be ornate and decorative, placing the center of the device at the level of the head of the seated listener, but any other position may be chosen depending on the use of this system. List of reference signs

[0024] a, b: central emission point of the boomers

[0025] c: central emission point of the tweeter

[0026] Bl, B2, B3, B4: mid-bass speakers (or boomers)

[0027] Bx, By: boomers in the [Fig.l]

[0028] Mx, My: boomer membranes Bx, By

[0029] P: central point fictitious resignation

[0030] T: treble speaker (or tweeter)

[0031] EH, FK, GJ, IL: intangible section planes

Claims

5 Claims

1. Sound emission device comprising a specific geometric assembly of 2 or more loudspeakers (B, T) characterized in that the average curvature of their respective membranes are centered on the same common point of convergence (P).

2. Stereophonic device characterized in that it consists of at least 2 devices according to claim 1.

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