GB2422066A

GB2422066A - Loudspeaker which can be used with or without stand which acts as a helmholtz resonator

Info

Publication number: GB2422066A
Application number: GB0500075A
Authority: GB
Inventors: Stephen John Halsall; Philip Jeffrey Anthony
Original assignee: GP Acoustics UK Ltd
Current assignee: GP Acoustics UK Ltd
Priority date: 2005-01-05
Filing date: 2005-01-05
Publication date: 2006-07-12
Anticipated expiration: 2025-01-05
Also published as: CN1802035A; GB2422066B; GB0500075D0

Abstract

The loudspeaker consists of an enclosure 1 with drive units 14 and a stand 2. The enclosure has an opening 16 in its base which can be closed by a base 50 (figure 5). The enclosure can then be used as a bookshelf speaker. Alternatively, the enclosure can be used on the stand which has an open top and contains a port tube 34 which acts as a Helmholtz resonator when the enclosure 1 is placed on the stand. Audio performance is thus enhanced.

Description

LOUDSPEAKER

This invention relates to loudspeakers.

The nventiofl:s concerned particularly with the improvement of the audio performance of relatively small loudspeakerS, often known as "bookshelf" speakers which can be placed on a shelf or similar support or can be mounted on a stand which usually rests on the floor.

The present invention provides an assembly of a loudspeaker enclosure comprising wall means defining a substanLiallY sealed enclosure having an opening in a lower portion thereof arid a closure foL closing the opening; and a stand having in an upper portion thereof means to receive the loudspeaker enclosure to provide support therefor, the stand comorisiflq at least one port tube and having an opening positioned to allow for interaction of air between the enclosure and The port tube(s) when the enclosure is supported by the stand, the port tube(s) having outlet openings which opon through the housing of the stand.

The loudspeaker enclosure of such an assembly can be used separately from the stand, the closure being positioned to close the opening and the enclosure thereby defining a substantially sealed enclosure. Such an enclosure can be mounted on, tor example, a shelf or on a stand of any convenient type.

Preferably however the enclosure is supported on the stand of the assembly with the closure removed. In this way, the port tube(s) function as a Heimhoitz resonator and serve to enhance the audio performance of thE.. speaker drive units.

conveniently, the opening in the wall means is in a bottom surface portion thereof and the opening in Lhe stand is in a top surface portion thereof.

Prereiably, the port tube(s) has/have inlet openings which are planar wito the opening of the stand.

This provices for a particularlY effective coupling between the enclosure and the port tubes.

Conveniently, the stand comprises r. housir.g in which the port tube(s) are located.

Advantageo5lY, the ho;sing is in the form of an upright tube in which the port tubc(s extend substantially v e r tic ally.

Preferably, the closure comprises a base for supporting the enclosure for se separately from the stand.

Advantageously, the enclosure has first electrical contact means which are positioned to make electrcal contact alternatively with second and third electrical contact means on the stand and the base respectively, the electrical contact means being arranged for supply of an audio signal to the drive unit(s) of the enclosure when the erciosure is mounted or. the stand and the base respectively.

Conveniently, the second and third electrical contact means are positioned at the upper end of respective cable ducts which extend upwardly from the stand and the hse respectively to be positioned at the rear of the enclosure when mounted on the stand and the base respectively.

An embodmenL of Lhe lnvenLion will now be described by ay of example with reference to the drawings of this

specification in which:

Fiqure 1 is a front perspective view of a loudspeaker assembly, the enclosure and stand of which are shown separated from each other; Figure 2 is a rear perspective view of the loudspeaker asserrbly shown in figure 1, the enclosure being shown supported on the stand; Figure 3 is an underneath perspective view of trte assembLy of igure 2; Fngure I is a section on the line V - IV of:Lgure 2; and Figure 5 is a rear perspective view of the enclosure of the loudspeaker assembly, shown together with a base, from which it is partially separated.

The loudspeaker assembly shown in the drawings consists of a loudspeaker enclosure 1 and a stand 2.

The enclosure 1 has a side wall 10 and a top wall 12.

The side wall has a shape such that the enclosure is elliptical in transverse section except for a flat front portion 11. The top wall 12 is elliptical in plan and therefore overhangs the flat front portion 11. Inc flat front wall portion 1 has five circular apertures, each aperture receiving a speaker drive unit 14. The drive units 14 may be of conventional construction and typically are arranged each to handle a range of frequencies in the audible range.

Alternatively, there may be a single drive unit, or any other desired number of units handling respective different 13 frequency ranges. The enclosure 1 is made from aluminium alloy in this emoodiment. Other suitable materials include plastics materials and MOE'. The shape of the cabinet is not important to its function: a rectilinear box could he used instead.

The enclosi.ire 1 is open at the bottom, the bottom thereby being formed as an opening 16. A sealing member 39 is locatee within the lower end of the side wall 10. The sealing member is shown separated from the enclosure 1 in figure 1. It consists of upper and lower steel plates 40, 41, between which gaskeL 42 of compressible closed-cell foam materidi is located. The plates 40, 41 arid the gaskeL 42 have a through aperture 43 of an approximately "figure-of-eight" shape. The sealing member 39 is located in the enclosure 1, firstly by being bonded around its periphery to the inner surface of the siOe wall 10 by an adhesive, and secondly by a pair of screws 38, 39 which pass through respective holes in the sealing member and are received in threaded sockets in respective bosses (not shown) formed on the interior of the side wall 10.

The stand 2 has a circular base 30 ane an uprignt tublar housing 32 of elliptical crosa-section, also formea from aluminium alley. The base 30 has a pair of recesses 31 in its lower surface which accommodate respective terminals 33 for connection to an amplifier or other suitoblc electrical signal socrce. The terminals 33 arc themselves connected to a further cable which runs within a tube 44 which extends within a recess 46 vertically up the rear of the stand 2 and the encLosure 1 to a plug connector 48 which is received in an lnput socket 45 located at the upper end of the rear surface of the enclosure side wall 10. The input socket 45 is connected by internal wiring to the drive units 14 by way of a suitable crossover circuit to separate the electrical signal into frequency bands appropriate to the individual drive units.

The housing 32 of the stand 2 contains a port tube 34 which is formed integrally with the housing 32 and extends vertically therein. As can be seen in figure 4, the port tube 34 has a section which is approximately rectangular on three sides and curved along the fourth. The upper end 38 of the tube 34 is open and les in the same plane as the upper open end of the cylindrical housing 32. A junction piece 46 which is formed as a plastics moulding is attached to the upper end of the housing 32. The junction piece 46 has an opening which fonts a sedi around LIie upper periphery of the port tube 34, Lhe inLerioi of which Lherefore opens through the junction piece 46. The junction piece 46 has means for releasably securing the lower end of the enclosure 1 to the stand 2 and has an upstanding annular wall which is shaped to fit in the lower end of the enclosure 1. The wall has on its upper edge a qasket (not shown) of compressible closed-cell foam material which is positioned to provide an air-tight seal with the underneath of the lower plate 42 of the sealing member 3.

An air-tight seal between the enclosure 1 and stand 2 is thus formed.

The housing 32 has in it first and second openings 36 which form outlets of the port tube 34. The combined areas ci the openings 36 cs substantially the same as the cross- sectional area of the port tube 34. The iocaion of the openings 36 is chosen so that the effective length of the tube 34 s such that it acts as a Helmholtz resonator having a frequency chosen to augment the frequency output of the drive units 14. The lower part of the port tube 34 beicw the outlet openings 36 contains a bun 47 which is formed from an acoiistc: foam material.

The loudspeaker enclosure 1 nay be used alone as a conventional "bookshelf" speaker. For this purpose, a base and a shorter cable tube 52, shown in figure 5 together with enclosure 1, are provided. The case 50 has elecLricai terminals 54 for connection to an amplifier or uther signal source. The tube 52 accommodates a cable (riot shcwn which extends from the terminals 54 to d connector 56 at the upper end of the tube 52. The connector 56 is positioned to be received in Lhe input socket 45 aLt he rear of the enclosure side wall 10.

The base 50 also has a closure member 58 which has an upstanding annular wall 59 (correspondinq to the psLanding wall of the junction piece 46) which is shaped to be received in the lower end of the enclosure wide wall 10 and to form an air-tight seal with toe sealing member 39 described above and located in the lower end of the side wall 10. The base 50 is secured to the enclosure 1 by a screw 60 which passes through a hole 62 in the base 50 and is received in a threaded socket 64 in the upper steel plate 40, the gasket 42 and lower plate 41 having respective holes through which the screw 60 passes.

A gasket (not shown) ot compressicle closed-cell material is fitted to the upper edge of the wail 59 and corresponds to the gasket of the:unction piece. Tightening of the screw 60 produces compression of the gasket beLween the wall 59 and the place 41, ensuring an air-tight seal. between the base 50 and the enclosure 10. Tt wil.l he noted that the lowermost part at the enclosure side wall 10 has formations which engace with the upstanding annular wall 59 of the base 50.

The terminals 54 may now be connected to a signal supply and the loudspeaker used.

When it is des:red to place the cnclosurc on the stand 2 and obtain the benefits of the port tube 34, the base 50 and cable tube 52 are removed and the enclosure I is placed on the upper end ot the ncusing 32 of the stanc 2, the securing means on toe junction piece 46 serving to join the enclosure 1 to the stand 2 in a releasacle manner. The terminals 33 are 0 connected to the signal supply. In this position, the i.cterio of the enclosure is in communication with the tube 31 which acts as a Ilelmhotz resonator and provides an enhancement of the sound produced by the enclosure.

Claims

CLAIMS: 1. An assembly of a loudspeaker enclosure comprisinc wail means

defiring a substanLially sealed enclosure arid having at least one drive unit. therein, Lhe enclosure having an opening in a lower portion thereof and a closure for closing the opening; and a stand having in an upper portion thereof means to receive the loudspeaker enclosure to provide support therefor, the stand compris:ng at least one port tube and having an opening positioned to allow for interaction of air between the enclosure and the port tube(s) when the enclosure is supported by the stand, the port tube(s) having outlet openings which open through the housing of the stand.
2. A loudspeaker assembly according to claim 1, in which the opon:ng in the wall means is in a bottom surface portion thereof and the opening in the stand is in a top surface portion thereof.
3. A loudspeaker assembly acccrding to any preceding claim, in which the port tube(s) has/have inlet openings which are coplanar with the openinG of the stand.
4. A loudspeaker assembly according to any preceding claim, in which the stand nomprises a housing in which the purL Lube(s) are loca:ed.
5. A loudspeaker assembly according Lu claim 4, in which the housing is in the form of an upright tube in which the port tube(s) extend substant:ally vertically.
6. A loudspeaker assembly according to any preceding claim, in hich the closure comprises a base for supporting the enclosure for use separately from the stand.
7. loudspeaker assembly according to claim 6, in wich the enclosure has first electrical con:act means which are positioned to make electrical contact alcernaLiely with second and third electrical contact means on the stand and the base respectively, the electrical contact means being arranged for supply of an audio signal to the dLive unit(s) of the enclosure when the enclosure is mounted on the stand and the base respectively.
8. A loudspeaker assembly according to claim 7, in which the second and third electrical contact rreans are positioned at the upper end of respective cable ducts which extend upwardly from the stand and the base respectively to be positioned at the rear of the enclosure when mounted on the stand and the base respectively.
9. A loudspeaker assembly substantially as hcrcinbeforo described with reference to the drawings.