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1. WO2021058976 - APPAREIL DE PROJECTION DE SON

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[ EN ]

SOUND PROJECTION APPARATUS

BACKGROUND

Field

The present technique relates to sound projection apparatus, which are configured to convert electrical signals into sound and to project the sound into a sound receiving space.

The present disclosure claims the Paris Convention priority of UK Patent Application number 1914001.1 filed on 27 September 2019 the content of which is incorporated herein by reference.

Description of Related Art

The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.

High fidelity audio equipment typically comprises an amplifier and two or more loud speakers. Electrical signals from various sources representing sound are amplified by the amplifier and fed to the loud speakers which convert the electrical signals into sound. Although “loud speaker” is a term which is conventionally used in respect of high fidelity audio equipment, the term “sound projection apparatus” is used in the following description to describe an apparatus which is configured to convert electrical signals into sound and to project the sound into a sound receiving space. Loud speakers would therefore be one example of sound projection apparatus.

There have been considerable advances in technology in respect of high fidelity audio equipment. Analogue electrical signals generated from tape or vinyl have been replaced with digital signals generated from media such as CDs with increased bandwidth and digital audio files which are compressed for streaming which can provide a reduction in noise and other sound defects compared with analogue formats. Furthermore advances in electronics and compression techniques have meant that there has been a great improvement in reproduction of the electrical signals representing the audio signals from a recorded source both in size, cost and quality. Dynamic range has almost doubled producing a resolution which matches that of the original master tapes. However, generally speaking the inventors have observed that the same improvements in sound quality and fidelity have not been reflected in the sound projection technology, particularly in the area of soundstage stability, clarity noise floor and listening position.

The present disclosure therefore presents an arrangement for improving fidelity of sound reproduced by sound projection apparatus from electrical signals representing audio signals.

SUMMARY

As will be explained in the following paragraphs, the present disclosure can help to provide improvements in or relating to sound projecting apparatus.

Embodiments of the present technique can provide a sound projection apparatus for projecting sound into a sound receiving space such as a room or auditorium. The sound projection apparatus comprises a bass unit having a housing which includes at least one cavity and at least one bass drive unit enclosed within the at least one cavity and an outlet port between the at least one cavity through the housing to the sound receiving space so that sounds generated by the bass drive unit in the at least one cavity can be projected into the sound receiving space. “Drive unit” is a term which is generally used herein for an electromagnetically activated cone which vibrates in accordance with the electrical signals received by the electromagnetic unit to generate sound. The sound projection apparatus further comprises a pod unit having a housing which forms a cavity and a plurality of drive units which are mounted within the cavity, the housing including a sound projecting face having an orifice for each of the plurality of drive units. A cone of each of the drive units is mounted outwardly in one of the orifices. In some examples the orifices are co-linear so that the drive units of the pod unit form a linear array. A suspension support arm is attached to the bass unit and extends from the bass unit where in use the pod unit is suspended in a vertical plane with respect to the bass unit from the suspension support arm.

Embodiments of the present technique can provide an improvement in high fidelity sound reproduction by arranging for a sound projection apparatus to include a bass unit and a suspension support arm which is attached to the bass unit so that a pod unit can be suspended above the bass unit. The suspension support arm is arranged to reduce vibrations or sound from travelling from the bass unit to the pod unit and in combination with a suspension arrangement of the pod unit from the suspension support arm reduces sound contamination from the bass unit into the pod unit. Correspondingly, sound and vibrations reproduced by the pod unit does not interfere with the bass unit.

Respective aspects and features of the present disclosure are defined in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and:

Figure 1 is a schematic representation of a sound projection apparatus according to an example embodiment of the present technique;

Figure 2 is a schematic view of an embodiment of two sound projection apparatus according to an example embodiment of the present technique;

Figure 3 is a plan view of an embodiment of a deployment of a stereo pair of the sound projection apparatus shown in Figure 2;

Figure 4 is a view of a conventional loudspeaker with a prior art configuration.

Figure 5 is a side view of the pod unit illustrating an advantage of one embodiment of the present technique.

Figure 6a is a view in the direction of an arrow A in Figure 4e of an example embodiment of the pod unit of Figures 1, 2 and 3;

Figure 6b is a view from a rear view of the example embodiment of the pod unit;

Figure 6c is a side view of the example embodiment of the pod unit;

Figure 6d is a schematic view of the example embodiment of the pod unit when it is disposed in its operating position with a wall side flat against the wall of a sound receiving space;

Figure 6e is a plan view of the example embodiment of the pod unit;

Figure 7a is a cross-sectional view of the cross-section AC-AC of Figure 4b;

Figure 7b is a cross-sectional view of the cross-section AD-AD of Figure 4b;

Figure 8a is a cross-sectional view parallel to a wall side of an upper part of the example embodiment of the pod unit shown in Figures 6a-6e, in which an elastic ball element forming part of a suspension of the pod unit is deformed;

Figure 8b shows the elastic ball element of Figure 8a in an un-deformed state;

Figure 9 is a schematic representation of an example embodiment illustrating an attachment of a suspension cord to the suspension support arm of Figures 1, 2 and 3;

Figure 10a is a cross-sectional view parallel to the wall of an example embodiment of the bass unit of Figures 1 and 2; Figure 10b is a view from the bottom of the bass unit; and

Figure 11 is a circuit diagram for connecting the bass drive units within the bass unit of Figures 10a and

10b.

DETAILED DESCRIPTION OF THE EMBODIMENTS

General Configuration

As explained above embodiments of the present technique can provide an improved sound projection apparatus which can more accurately generate a representation of an original audio signal from electrical signals representing the audio signal and project the reproduced sound into a sound receiving space. A sound receiving space may be a living room or an auditorium or a similar room, where for example high fidelity equipment is disposed. One example of a sound projection apparatus according to an example embodiment is shown Figure 1.

As shown in Figure 1, a sound projection apparatus 1 comprises a bass unit 10 and a pod unit 12. Attached to the bass unit is a suspension support arm 14. In use the sound projection apparatus is mounted on a horizontal surface such as the floor 16 of a room and extends vertically as represented by arrow 18 from the floor 16. The suspension support arm 14 therefore extends vertically above the bass unit 10 and is securely attached to the bass unit by some means such as glue or fastening means such as screws or nails. The pod unit 12 is suspended from an upwardly extending part of the suspension support arm 14 at a point 20 by a suspension cord 22. As will be explained shortly the pod unit 12 is attached to an end of the cord 22 so that the pod unit 12 is suspended from the upper section of the suspension support arm 14 and therefore hangs above the bass unit 10.

As will be appreciated the bass unit forms a base of the sound projection apparatus when in use so that the bass unit can also be referred to as a base unit.

The dimensions of the pod unit 12, bass unit 10 and suspension support arm 14 can vary and accordingly the example embodiments are not limited by the dimension of the various elements 10, 12, 14. However in one example the height of the sound projection apparatus is generally consistent with the height of a human being 17.

The pod unit 12 as shown in Figure 1 is substantially segment shaped (as in segments of an orange) and includes a sound projection face 30 which provides a substantially flat face. The sound projection face 30 includes a plurality of orifices 32 which may be in a separate plate which is then mounted into the sound projection face 30. As will be explained shortly, the pod unit 12 includes a cavity formed within the housing of the pod unit 12. The cavity formed in the sound projecting face 30 is closed by the plate forming the orifices 32 (not shown in Figure 1) and a plurality of drive units are mounted within the cavity so that a cone or sound projecting element of each of the drive units faces outwards through one of the orifices 32. The drive units mounted in the orifices therefore form a linear array of sound producing devices in the pod unit 12.

Also explained in more detail below the bass unit 10 includes bass drive units which generate bass sound signals which are projected into the sound receiving space via an outlet port 40.

Although Figure 1 shows an example of one sound projection apparatus, it will be appreciated that conventionally the sound projection apparatus are used in pairs such as left and right components of a stereo system. Accordingly Figure 2 provides an example illustration of two sound projection apparatus 50, 60 disposed to form a stereo pair with a left-hand sound projection apparatus 50 being used to generate signals for a left channel of the stereo pair and the right-hand sound projection apparatus shown in the drawing 60 representing a sound projection for the right channel of the stereo pair. As we appreciated in Figure 2 the sound projection apparatus for the left and right channels 50, 60 are similar or identical and correspond to the example shown in Figure 1 and so further description will not be given. However as illustrated in Figure 2 the left and right sound projection apparatus 50, 60 are disposed so that they face inward so the respective sound projection faces 30.1, 30.2 face inward into the sound receiving space 80.

Figure 3 provides an example illustration of a deployment of a stereo pair of sound projection apparatus shown in Figure 2 within a sound receiving space 80 formed within a room comprising a back wall 82 and two side walls 84, 86. As will be appreciated other parts of the room may also exist but these are not shown. As shown in Figure 3 which provides a plan view of an example deployment of the stereo pair of sound projection apparatus 50, 60 shown in Figure 2, the left channel sound projection apparatus 50 is mounted against the left-hand side of the back wall 82 and the sound projection apparatus 60 for the right-hand channel of the stereo pair is mounted on the right side of the room against the back wall 82. In use therefore the sound projection apparatus projects sound into the sound receiving space 80 as illustrated by wave fronts 90, 92.

As will be explained shortly, the sound projection face 30 of the pod units 12 is arranged to be at an angle with respect to a flat wall side of the pod unit 12 which are mounted adjacent the back wall 82 in a deployment. Accordingly with the angle of the projection face 30 at a pre-configured angle to the flat wall side, sound is projected from the pod unit 12 into the room so that a listener can receive the sound directed from the pod units 12 without introducing phase errors or at least reducing the likelihood of phase errors which can occur when conventional speakers are sited out in the room forming the sound receiving space creating time delays due to sound traveling from the speakers and then being reflected from the back wall 82. More explanation is provided below with reference to Figures 4 and 5, wherein Figure 4 is a diagram representing a deployment of conventional sound projection devices (loud speakers), whereas Figure 5 is a diagram illustrating advantages provided by an example deployment of an example embodiment. As will be explained, in some examples the angle between the sound projecting face and the wall face of the pod unit 12 is approximately 60°.

Pod Unit

An example illustration of a pod unit 12 shown in Figures 1, 2 and 3 will now be described in more detail. An example embodiment of a pod unit is shown in Figure 6a, 6b, 6c, 6d, 6e. As shown in Figure 6a and 6e, Figure 6a provides a view in the direction of arrow A in Figure 6e. Figures 6a to 6e show a general example of a pod unit 12. The pod unit 12 as mentioned above is according to one example segment shaped with Figure 6a illustrating a face on view of the projection face 30 of the pod unit 12. As can be seen in Figure 6a the sound projection face 30 houses a plurality of drive units 100 which are mounted in orifices 32 to project sound outward into the sound receiving space 80. As will be explained shortly the pod unit 12 comprises a housing 200 within which a cavity 202 is formed and the drive units 100 are mounted in the orifices 32 to project sound outward from the cavity 202 into the room. As mentioned above, according to one example a cover plate 102 is formed to fill an open hole into which the cover plate fits, the cover plate including the plurality of orifices 32 in which the plurality of drive units 100 are mounted.

Figure 6b provides a view from the rear of the pod unit 12 that is the side which is adjacent the back wall 82 in Figure 3. This is referred to above as the flat wall side 104. As shown in Figure 6b and 6c, in one example the wall side 104 of the pod unit 12 is substantially flat. Figure 6d shows the pod unit 12 when disposed in its operating position with the wall side 104 flat against the wall 82 of the sound receiving space 80. Figure 6e provides a plan view from the top of the pod unit 12 which illustrates the wall side 104 and the sound projecting face 30. As shown in Figure 6e a rear section 106, opposite the sound projecting face of the pod unit 12 is curved in order to reduce a possibility of sound reflections internally within the cavity formed within the housing which has a corresponding shape. Two holes 110, 112 appear in the top of the pod unit 12. One of the holes 110 is arranged to receive the suspension cord 22 which is fixed inside the pod unit 12 for the pod unit 12 to be suspended from the suspension support arm 14. The other hole 112 is used to feed electrical cables required to connect the drive units 100 to the electrical signal source.

As explained above the pod unit 12 comprises housing 200 within which a cavity 202 is formed. Figure 5a and 5b provide cross-sectional views of the pod unit 12 shown in Figures 6a to 6e and in particular Figure 6b at a section AC-AC in Figure 7a and at a section AD-AD in Figure 7b. As shown in Figure 7a the pod unit 12 as shown through the cross-section AC-AC is formed from housing 200 and the housing 200 is constructed to form a cavity 202 within which the plurality of drive units 100 are mounted. Thus the cavity 202 forms an air load for the drive units 100 to drive sound into the sound receiving space 80. Each of the plurality of drive units 100 include an electric-mechanical part 210 and a cone 212 which converts vibrations induced by the electro-mechanical part 210 into the sound waves which are projected by the drive unit 100 into the sound receiving space 80. As explained above the cone 212 is mounted so that it is flush with the orifice 32 in the sound projection face 30 of the pod unit 12.

Figure 7b provides a corresponding view of the cross-section AD-AD of Figure 6b and shows a second one of the plurality of sound drive units 100 within the cavity 202 formed by the housing 200 so that the cavity 202 provides a continuous volume within which the plurality of drive units 100 are mounted. For the example shown in Figures 5, 6a, 6c and 6d, there are eight drive units 100 which are mounted substantially at head height when the sound projection apparatus 1 is deployed.

As illustrated in Figures 7a and 7b, the cavity 202 forms a continuous void in which the drive units 100 can generate sound projected outwardly from the sound projecting face 30. The closer to the centre of the cavity the larger the cross-sectional area. The cavity 202 of the pod unit 12 is formed with an ellipsoid cross-sectional shape as shown by a line 220 illustrated in Figures 7a and 7b. Providing an ellipsoid cross-sectional area for the cavity 202 has an advantage in reducing reflections or reverberations as a result of sound reflected from a rear of the drive unit 100 into the cavity 202.

As mentioned above, the wall-side 104, which is substantially flat and configured to be adjacent a wall of the sound receiving space 80 may be formed by the housing of the pod unit 12 to provide an angle of

sound projection face 30 to the wall of between 45 and 80 degrees and preferable 60 degrees. The angle provides an arrangement whereby the sound projected from the sound projecting face 30 projects sound along the wall and into the room to optimise a distribution of the sound within the room. This eliminates or at least reduces problem faced by most conventional loudspeakers in the form of the precedence and proximity effect where due to conventional drive units parallel to the wall producing concentric waveforms, most of the radiation obeys the inverse square law decaying at 6dB per doubling of distance. This limits the optimum listening position to the apex of an equilateral triangle whose corners are formed by the position of the listener and the two loudspeakers. Conventionally, if one moves away from this apex position of an equilateral triangle the sound from a nearer of the speakers will grow in volume inversely proportionally to the square of the distance. This can have deleterious consequences for any sound sources between the speakers as their image will lose focus and be distorted in width. This destroys or at least harms the “suspension of disbelief’ of listening to a live performance

As illustrated in Figure 4, this issue of the precedence and proximity effect causing a listening position to be at the apex of an equilateral triangle is further complicated in most conventional speakers by the use of drive units of disparate sizes 303 sharing a common front plate. As shown for example in Figure 4 the drive units have disparate sizes 303, which may also be fabricated with cones or domes made from disparate materials. As illustrated in Figure 4, sound can travel at different speeds in different materials and the different size of the transducers create different sized wave fronts 300. This all adds further to damaging a structure of the original signal as sections of it move in time. If one adds to this the phase and magnitude errors created by conventional 2nd 3rd and 4th order crossover filters designed to marry the frequencies of these different drive units but in doing so more time smears and damage to transient responses are created jumbling the arrival order of vital spacial cues captured on the original recording. These spacial cues are interpreted by the human ear/brain interface and are how we determine if the sound is real. If missing or damaged the listener instinctively knows that the sound is not real.

An improvement in sound quality/fidelity can be provided by a combination of a lack of conventional crossover made possible by a bandwidth of the array of drive units 303, the wall mounting at an angle of 60 degrees and the wave front being created by a linear array of drive units. This is illustrated in Figure 5, in which centres of the drive units are close together. Furthermore, in some embodiments, for over nine octaves sound can be projected from sixteen drive units of the same size made from the same material. All these factors combine according to example embodiments to create projected sound image that is stable in space and sounds real for a listener seated in a room behind a line approximately 150cm parallel and in front of the pods

Due to a combination of angle to the wall and a cylindrical wave front created by the linear array, the sound can be arranged to decay for some distance at 3dB per doubling of distance providing half as much again dynamic range and create stable realistic images for a listener. This can be appreciated by comparing Figure 4 with Figure 5, because in Figure 4 wave fronts interfere with reflections from the rear wall 82 whereas in Figure 5 consolidated cylindrical wave fronts are formed when seated anywhere in the listening room (sound receiving space) beyond a line 150cm parallel and in front of the pods 12.

In some examples in order to reduce reflections, reverberations and other distortions, the cavity 202 within the pod unit 12 may be filled with a sound dampening material. In one example the sound dampening material may be TWARON (RTM). In another example the sound dampening material may be silk. In another example in order to provide an advantage of reducing damage to the environment, the sound dampening material may be Peace Silk and Alpaca Wool.

As explained above the pod unit 12 is suspended from the support arm 14 by the suspension cord 22. In order to further improve the sound isolation, an arrangement is provided which provides a dampening attachment of the suspension cord 22 to the pod unit 12. Such an arrangement is shown in Figures 8a and 8b. As shown in Figure 8a, and as explained above, a hole 110 in the housing 200 is formed for the suspension cord 22 to pass through the housing 200 and into the cavity 202. Attached to the end of the suspension cord 22 is an visco-elastic element 240 which is attached to the end of the cord and adapted to fill a space 242 so that the visco-elastic element 240 is forced against an upper space of a shaped formation 242, 244 of the cavity preventing the cord 22 from escaping from the hole 110 and thus suspending the pod unit 12 from the support arm 14 by the suspension cord 22. As a result of the weight of the pod unit 12 on the visco-elastic element 240, the visco-elastic element 240 is crushed from its original shape shown in Figure 8b to the form in which deformed as shown in Figure 8a. In one example as shown in Figure 8b the visco-elastic element 240 is a sphere or ball and is attached to the end of the cord 22 by using a washer or flange 246 which is attached to the suspension cord 22 so that the visco elastic element 240 can travel down the cord and be forced against the washer 246 by the shaped formation 242, 244 of the upper end of the cavity 242.

As mentioned above, in one example the visco-elastic element 240 is a sphere and in one example the sphere is formed as two hemispheres as a visco-elastic material. In one example the visco-elastic material 240 is a polyurethane material. In one example the visco-elastic element 240 is formed from SORBOTFiANE (RTM). According to one example the SORBOTHANE ball is crushed by action of the weight of the pod unit 12 against the end of the suspension cord 22 so that it reaches a non-Newtonian fluid state in which it is reduced by up to 30% of its original height. In order to achieve this, the Sorbothane is fabricated to a density of 70 Durometer or Shore parameter measurement.

In one example the suspension cord 22 is fabricated from stainless steel although it will be appreciated that other materials could be used.

An example arrangement for attaching the suspension cord 22 to the suspension support arm 14 is shown in Figure 9, which corresponds substantially to the diagrams of Figures 8a and 8b so only the differences will be described. As shown in Figure 9 a second visco-elastic sphere 250 is used at an end opposite to that of the pod unit 12. The suspension cord 22 passes through the suspension support arm 14 and the second sphere 250. Unlike the example embodiment shown in Figures 8a and 8b, after passing through the first and second visco-elastic spheres 240, 250, the suspension cord 22 is crimped at either end 252, 254 to ensure that the suspension cord 22 is not pulled through the spheres 240, 250 when under load from a weight of the pod unit 12. Again compression of the spheres 240, 250 under the weight of the pod unit 12 causes the spheres 240, 250 to be compressed. Both of the visco-elastic spheres 240, 250 may be made from SORBOTHANE. The first and second spheres 240, 250 may reduce vibrations such as for example by approximately 94%.

Bass Unit

An example embodiment of the bass unit 10 shown in Figures 1, 2 and 3 will now be described with reference to Figures 10a, 10b and 11. As shown in Figures 10a and 10b, the bass unit 10 is formed from a housing 300 with a first cavity 302 and a second cavity 304. Within each of the first and second cavities 302, 304 is a bass drive unit 312, 314. The bass drive units 312, 314 comprise an electro-magnetic drive unit 410 and a cone 412 in which the electro-magnetic unit 410 causes vibrations within the cone 412. As shown in Figure 10a the bass drive units 312, 314 are attached to a section of the housing 320 adjacent one another and facing into a wall 320 of the housing 300. The first and second drive units 312, 314 are arranged to produce bass sounds in accordance with an asymmetric isobaric dual effect band pass enclosure. That is to say, the cones of the drive units 412 face one another either side of the section of the solid housing 320 and generate sounds into the respective cavities 302, 304 from the back of the cone units 412. Furthermore the bass drive units 312, 314 are arranged within their respective volumes formed by the first and second cavity 302, 304 to match the frequencies which are generated from the drive units 312, 314. Sound generated from the first drive unit 312 and projected into the cavity 302 is projected out of the cavity 302 by a first outlet port 352. Correspondingly, sound generated by the second drive unit 314 into the second cavity 304 is projected out from the cavity 304 via a second outlet port 354. As shown in Figure 10a according to one example the first and second outlet ports 352, 354 are arranged to be concentric so that the sound emits from both drive units from the same source. Figure 10b provides a view from the bottom of the bass unit shown in Figure 10a to show that the first and second outlet ports 352, 354 are disposed in a concentric arrangement, although each emits sound from the different first and second cavities 302, 304. The first and second outlet ports 352, 354 are arranged as dual concentric outlet ports so that sound at different bass frequencies is emitted from each of the respective bass drive units 312, 314 from their cavities 302, 304.

As explained above, the first and second bass drive units 312 and 314 are arranged in a clamshell configuration as an isobaric asymmetric formation. As indicated above, there is a relationship between the volume of the cavities 302, 304 in which each of the drive units 312, 314 is mounted and a frequency to which the drive units 312, 314 are tuned. The first larger cavity 302 in one example is tuned to a frequency of 40 Hz and has a volume which is approximately 25 litres. The second drive unit 314 is tuned to a frequency of 80 Hz and has a smaller volume of 5 litres. Although other volumes could be used, the ratio of the volumes of the first and second cavities 302, 304 of the bass unit 10 should be in the order of 5:1 with the respective tuned frequencies according to the Helmholtz resonance set at respectively 1:2. The port volumes effect a phase inversion so as the cones move in one direction the air mass in the ports moves in the opposite direction. This added mass has the effect of doubling the cone area thereby greatly extending the capability of the cones to produce frequencies well below their free air resonant frequency. The dual ports therefore work in tandem and are the equivalent of an impedance matching transformer. Their summed volumes effect a mass load on the cones at once reducing amplitude and in turn reducing distortion and improving power handling.

Many speakers use single reflex ports but the combination of a four voice coil engine in an isobaric configuration with dual concentric asymmetric ports can provide an advantage in producing superior speed control and power handling at frequencies below 90Hz.

A further example aspect of the present technique concerns the wiring of the bass drive units 312 within the bass unit 10. As shown in Figure 11 a circuit diagram is shown for connecting the drive units 312 to the signal source. Conventionally the first and second drive units 312, 314 include two voice coils 401,

402. Thus the first bass drive unit 312 includes two voice coils 401, 402 and the second drive unit 314 includes first and second drive voice coils 403, 404. Each voice coil has a positive and negative input for connecting to positive and negative electrical signals of a feed channel. As shown in Figure 11 a positive of the input is connected to both positives of the first and second voice coils 401, 402 of the first drive unit 312. The negatives of the first and second voice coils 401, 402 are connected to the first and second drive coils 403, 404 of the second bass drive unit 314. The positives of the first and second voice coils

403, 404 are connected to a negative of the output. Accordingly with each of the voice coils having a resistance of 6 Ohms, an overall resistance of the voice of the bass unit when connected to the output is 6 Ohms. As such, the first and second bass drive units are each driven by two voice coils, each voice coil having positive and negative inputs the two voice coils for the first and the second bass drive units being connected to provide an improved efficiency, by optimising a resulting inductance.

According to the example embodiments, the perceived noise floor of a given recording can be reduced by a speed of the bass drive units. A rise time of the bass or transient response can be improved with the disclosed embodiments compared with conventional bass units even in an isobaric configuration, which is affected by more mass with less magnetic flux to drive it. A result is that although the speaker measures the same in terms of frequency response, the bass driver responds much more slowly than the other drive units. This can result in slurring of sound which can be enough to mask fine detail and damage an imaging due to timing/phase shift in bass range making the psycho acoustics more difficult to perceive hence a higher noise floor.

According to some embodiments, the sound projecting apparatus 1 may also include a choke, which can be conveniently mounted in the base unit. The choke may be a first order large metal foil crossover choke, which for example at lOmH crosses over at around 500Hz. By using a single choke, a linear phase and magnitude response can be maintained. This can preserve vital spatial and timing cues and which can help make sound more real.

Construction

According to some example embodiments the housing of the bass unit 10, the suspension support arm 14 and the pod unit 12 are fabricated from a wood such as bamboo or laminated bamboo or engineered bamboo, such as 40mm bamboo thickness. This provides both structural rigidity and sound absorption and also uses of environmentally friendly materials.

In some examples the cavities 302, 304 of the bass unit may be filled with silk such as peace silk in order to improve the environmental qualities of the sound projection apparatus. In some examples the drive units 100 and the bass drive units 312, 314 have cones 412 which may be made of Aluminium or anodized Aluminium in order to improve an operational bandwidth and frequency response of the cones when driven by the voice coils. Thus each drive unit may comprise an electromechanically activated cone in fabricated Aluminium.

Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting of the scope of the invention, as well as other claims. The disclosure, including any readily discernible variants of the teachings herein, define, in part, the scope of the foregoing claim terminology.

Respective features of the present disclosure are defined by the following numbered paragraphs:

Paragraph 1. A sound projection apparatus for projecting sound into a sound receiving space, the sound projection apparatus comprising

a bass unit having a housing including at least one cavity and at least one bass drive unit enclosed within the at least one cavity and an outlet port between the at least one cavity through the housing to the sound receiving space for bass sounds generated by the bass drive unit in the at least one cavity to be projected into the sound receiving space,

a pod unit having a housing which forms a cavity and a plurality of drive units which are mounted within the cavity, the housing including a sound projecting face having an orifice for each of the plurality of drive units, a cone of each of the drive units being mounted outwardly in one of the orifices, and

a suspension support arm attached to the bass unit and to extend from the bass unit, wherein the pod unit is suspended from the suspension support arm.

Pod unit

Paragraph 2. The sound projection apparatus of paragraph 1, wherein the sound projection apparatus is configured to be mounted in use adjacent/attached to a wall of the sound receiving space, the housing of the pod unit having a substantially flat wall side for mounting against the wall, the sound projecting face in which the plurality of drive units are mounted in the plurality of orifices being formed adjacent to the substantially flat wall side, and an angle between the flat wall side and the sound projection face is formed at a projection angle so that when the substantially flat wall side is mounted against the wall of the sound receiving space sound is projected outward at the projection angle with respect to the wall of the sound receiving space.

Paragraph 3. The sound projection apparatus of paragraph 1 or 2, wherein the projection angle is between 45 and 80 degrees.

Paragraph 4. The sound projection apparatus of paragraph 3, wherein the projection angle is 60 degrees.

Paragraph 5. The sound projection apparatus of paragraphs 1 to 4, wherein the plurality of drive units of the pod unit are arranged into a linear array, the linear array being formed vertically in use.

Paragraph 6. The sound projection apparatus of paragraphs 1 to 5, wherein the pod unit is suspended by the suspension chord from the suspension support arm so that a height for the linear array is at a listening position.

Paragraph 7. The sound projection apparatus of paragraphs 1 to 6, wherein the cavity of the pod unit has an ellipsoid cross-section to provide an air load with respect to each of the drive units, to minimise reflective distortion.

Paragraph 8. The sound projection apparatus of paragraphs 1 to 7, wherein the cavity includes damping material.

Paragraph 9. The sound projection apparatus of paragraph 8, wherein the damping material is peace silk.

Suspension support

Paragraph 10. The sound projection apparatus of paragraphs 1 to 9, wherein the suspension support arm is substantially accurate extending from and arcing over the bass unit so that the pod unit is suspended above the bass unit.

Paragraph 11. The sound projection apparatus of paragraph 10, wherein a height which is approximately the height of a human being.

Paragraph 12. The sound projection apparatus of paragraphs 1 to 11, wherein the pod unit is suspended above the bass unit by a chord attached at one end to the pod unit and the other end to the suspension support arm.

Paragraph 13. The sound projection apparatus of paragraph 12, wherein the chord includes stainless steel.

Paragraph 14. The sound projection apparatus of paragraph 12 or 13, wherein the chord passes through the housing of the pod unit into the cavity and a visco-elastic element is attached to the end of the chord inside the cavity and the pod unit is suspended by action of gravity with the visco-elastic element being compressed against the housing inside the cavity.

Paragraph 15. The sound projection apparatus of paragraph 14, wherein the visco-elastic element is a sphere formed from a polyurethane material.

Paragraph 16. The sound projection apparatus of paragraph 14 or 15, wherein the visco-elastic element is a ball formed from a polyurethane material.

Bass unit

Paragraph 17. The sound projection apparatus of paragraph 1, wherein the bass unit comprises first and second cavities formed within the housing and a first bass drive unit mounted within the first cavity and a second bass drive unit mounted within the second cavity.

Paragraph 18. The sound projection apparatus of paragraph 17, wherein the first cavity has a first outlet port which connects the first cavity to the outside air for allowing sound generated by the first bass unit to pass to the sound receiving space, and the second cavity has a second outlet port which connects the second cavity to the outside air for allowing sound generated by the second bass unit to the sound receiving space.

Paragraph 18. The sound projection apparatus of paragraph 17 or 18, wherein the first outlet port and the second outlet port are configured to be dual concentric ports.

Paragraph 19. The sound projection apparatus of paragraph 17, 18 or 19, wherein a ratio of a first volume provided by the first cavity to a second volume provided by the second cavity is matched to bass frequencies generated by the first bass drive unit and bass frequencies of the sound generated by the second bass drive unit.

Paragraph 20. The sound projection apparatus of paragraph 19, wherein the ratio of the first and second volume is inversely proportional to a ratio of Helmholtz resonance frequencies produced by the first and second bass drive units.

Paragraph 21. The sound projection apparatus of paragraph 19 or 20, wherein the first volume is 25 litres and tuned to a Helmholtz resonance of 40Hz, and the second volume is 5 litres and tuned to a Helmholtz resonance of 80Hz.

Paragraph 22. The sound projection apparatus of paragraphs 17 to 21, wherein the first bass drive unit and the second bass drive unit are mounted in an isobaric clamshell configuration opposite one another in the first and second cavities respectively.

Paragraph 23. A method of deploying a pair of sound projecting apparatus of paragraphs 1 to 22 in a sound receiving space, each of the sound projecting apparatus comprising a bass unit having a housing including at least one cavity and at least one bass drive unit, a pod unit having a housing which forms a cavity and a plurality of drive units which are mounted within the cavity, the housing of the pod unit having a substantially flat wall side and a sound projecting face in which the plurality of drive units are mounted in the plurality of orifices being formed adjacent the flat wall side at a projection angle to the flat wall side, and a suspension support arm attached to the bass unit and extending from the bass unit, the method comprising

locating a first of the pair of sound projecting apparatus on one side against a back wall of the sound receiving space so that the first sound projecting apparatus is mounted vertically with the bass unit on the floor and the pod unit is suspended from the suspension arm extending vertically and the flat wall side of the pod unit is mounted against the back wall of the sound receiving space so that the sound

projecting face of the pod unit is arranged at the projection angle to the back wall and faces towards a second of the pair of sound projection apparatus, and

locating the second of the pair of sound projecting apparatus on another side against the back wall of the sound receiving space so that the second sound projecting apparatus is mounted vertically with the bass unit on the floor and the pod unit is suspended from the suspension arm extending vertically and the flat wall side of the pod unit is mounted against the back wall of the sound receiving space so that the sound projecting face of the pod unit is arranged at the projection angle to the back wall and faces towards the first of the pair of sound projection apparatus.