EP0111408A1 - Lautsprechergehäuse - Google Patents

Lautsprechergehäuse Download PDF

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Publication number
EP0111408A1
EP0111408A1 EP83307326A EP83307326A EP0111408A1 EP 0111408 A1 EP0111408 A1 EP 0111408A1 EP 83307326 A EP83307326 A EP 83307326A EP 83307326 A EP83307326 A EP 83307326A EP 0111408 A1 EP0111408 A1 EP 0111408A1
Authority
EP
European Patent Office
Prior art keywords
sound
cabinet
drive unit
cabinet according
walls
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83307326A
Other languages
English (en)
French (fr)
Inventor
Graham Bank
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CELESTION INTERNATIONAL Ltd
Original Assignee
CELESTION INTERNATIONAL Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CELESTION INTERNATIONAL Ltd filed Critical CELESTION INTERNATIONAL Ltd
Publication of EP0111408A1 publication Critical patent/EP0111408A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H04R1/2869—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself
    • H04R1/2876—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of damping material, e.g. as cladding
    • H04R1/288—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of damping material, e.g. as cladding for loudspeaker transducers

Definitions

  • This invention relates to loudspeaker cabinets.
  • Many different designs of loudspeaker cabinet have been proposed with a view to reducing the effect of resonances. It is known for example that when considering the rigidity of a speaker cabinet one must take into account bending resonances and also resonance effects resulting from the interaction of the mass of the panels and the compliance of the enclosed volume of air. It is known that one way to raise this resonance in frequency is to reduce the mass of the panels from which the cabinet is made. Attempts have been made to find panels which are both lighter and stiffer than wood.
  • One proposal which has been made, as mentioned for example in "Hi-Fi Answers", July 1982, is to use panels of a sandwich construction, similar to that used for aircraft panels.
  • Such sandwiches comprise two thin sheets of aluminium or aluminium alloy separated by an aluminium or aluminium alloy honeycomb structure.
  • Panels made from such sandwich material have an extremely high stiffness to mass ratio, and in theory are therefore well-suited for use as panels for a loudspeaker cabinet.
  • sandwich-type material although having a high stiffness to mass ratio, performs less well than chipboard panels when one considers the effect known as critical frequency. Above a particular frequency, known as the critical frequency, a panel becomes substantially transparent to sound, and at frequencies above this critical frequency the panels of the loudspeaker cabinet allow sound to escape through the panels. This can cause colouration of the sound for example. Consequently, because of this lowering -of the critical frequency, and also because of the considerable cost of the basic sandwich material, the use of such material for the panels of loudspeaker cabinets has been effectively dismissed.
  • the present invention is based upon the discovery that the problem of critical frequency can be overcome, using panel material having a high stiffness to mass ratio, if one includes acoustic absorbing means arranged appropriately within the cabinet.
  • a loudspeaker cabinet comprising walls of a material having a high stiffness to mass ratio at least one drive unit, and sound-absorbing means within the enclosure defined by the walls, said sound -absorbing means being of a composition and/or so arranged that its sound-absorbing properties differ in dependence on its position in the cabinet.
  • the effect of the sound-absorbing means is to overcome, or at least substantially reduce, the adverse effect of critical frequency, and to balance the effects of reflection and absorption of sound and thus avoid or reduce the transparency of the cabinet to sound.
  • the sound-absorbing means comprises foam material positioned within the cabinet.
  • the sound-absorbing means may be positioned simply around the drive unit or drive units, or alternatively, may be designed substantially to fill the cabinet enclosure.
  • the absorbing material forms an acoustic "wedge", i.e. is acoustically graded so that its frequency absorption characteristics gradually change as one moves further away from the drive unit or units.
  • the loudspeaker cabinet is shown as comprising a top panel 10, a rear panel 12, two side panels (one of which is shown at 14), a base 16 and a front panel 18.
  • all the panels are made of a sandwich material having a high stiffness to mass ratio.
  • One such material which is suitable for use is a sandwich comprising two sheets of aluminium or aluminium alloy filled with a honeycomb of aluminium or aluminium alloy foil.
  • a typical material is that sold by Ciba-Geigy and known by the trademark "Aeroweb".
  • Such a sandwich has a honeycomb core made by fastening ribbons of foil together in a layered slab by suitably spaced adhesive stripes perpendicular to the long axis of the ribbons and then expanding the slab to produce a hexagonal cell structure, as indicated at 20 in Fig. 1.
  • the sandwich is notably stiffer along -the long axis of the ribbons than perpendicular thereto.
  • the panel material is arranged so that the ribbons of the honeycomb structure run parallel to the longer sides of each panel. In the embodiment shown, the line of the ribbons runs vertically for the two side panels 14, and for the front panel 18 and rear panel 12, and from side to side of the cabinet for the top panel 10 and base 16.
  • the base 16 of the cabinet is formed in two pieces, joined at the centre of the base, with each base portion being a continuation of the respective side panel.
  • the top panel 10, the two side panels 14 and the two portions of the base 16 can be made from one length of sandwich material suitably machined, folded and wrapped around to form the desired rectangular configuration.
  • the front panel 18 and the rear panel 12 can then be fitted into the open-ended box defined by the other panels, and can be suitably secured in place, for example by adhesive.
  • the front panel 18 has cutouts 22 to receive the loudspeaker drive units (not shown).
  • a rebated panel 24 is laminated to the front panel 18 to enable flush mounting of the drive units.
  • a particularly preferred "Aeroweb” material is that known as Type 3003. This has a minimum compression strength of 2.76 MN/m 2 , a nominal longitudinal beam shear strength of 2.2 MN/m 2 , a nominal transverse beam shear strength of 1.6MN/m 2. a nominal thickness of 12.5mm. and an average weight of 4.6Kg/m 2 .
  • Fig. 2 illustrates one way in which a sound-absorbing means can be incorporated within the cabinet enclosure.
  • a plurality of blocks 28 of sound- absorbent material preferably a foam material, are positioned around the drive unit 29 and are appropriately secured in place.
  • Fig. 3 shows an alternative arrangement in which layers 30 of flexible sound-absorbing material are wrapped around the drive unit 29.
  • the layers 30 may be provided only in the immediate vicinity of the drive unit, or can be arranged substantially to fill the cabinet enclosure.
  • Fig. 4 shows yet another way of providing a sound-absorbing means within the cabinet shell.
  • the sound-absorbing material comprises a plurality of generally triangular cross-section pieces 32 of sound-absorbing material, such as a foamed material, formed as wedges or prisms and suitably arrayed to form a sound-absorbing barrier.
  • These triangular cross-section elements 32 need not necessarily all be of the same material or all have the same sound-absorbing characteristics. For example, one could make up the barrier from two different materials, designed to absorb different frequency ranges, and positioned alternately, as indicated for example by the cross-hatching in Fig. 4.
  • the individual blocks or wedges 32 could either be fitted piece- by-piece into the cabinet enclosure, or alternatively the pieces could be glued on to a fabric backing in an appropriate configuration so that the fabric with the pieces glued thereon could then simply be folded and inserted as a unit into the cabinet enclosure.
  • the sound-absorbing material is appropriately graded in relation to its position within the cabinet enclosure so that there is a change in its sound-absorbing properties as one moves away from the drive unit towards the cabinet panels.
  • Absorbent materials which have low sound-absorbing properties are also substantially non-reflective of sound waves, i.e. the sound waves pass easily through them. Similarly, highly absorbent materials are more reflective of sound waves.
  • the absorbing material within the enclosure is graded so that the material nearer to the drive unit is lightly absorbent and therefore substantially non-reflective, while the material most remote from the drive unit is strongly absorbent and therefore more reflective. This has the advantageous result that the sound waves within the enclosure are not reflected back to the drive unit by the first absorbing material which they encounter, and additionally the subsequent absorbing material absorbs most of the waves, thereby to prevent them reaching the cabinet walls. In other words both the drive unit and the cabinet walls are substantially freed from direct or reflected sound waves.
  • panels of metal honeycomb structure have been described as advantageous, other panel structures having a high stiffness to mass ratio could alternatively be used, for example sandwich panels of porous or cellular material between strong skins.
  • the core material could be stiff foam plastics, cellulose fibre, paper, etc., and the skins could be of metal, plastics or hardboard for example.
  • the present invention is also applicable to cabinets having alternative configurations.

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
EP83307326A 1982-12-02 1983-12-01 Lautsprechergehäuse Withdrawn EP0111408A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8234430 1982-12-02
GB8234430 1982-12-02

Publications (1)

Publication Number Publication Date
EP0111408A1 true EP0111408A1 (de) 1984-06-20

Family

ID=10534701

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83307326A Withdrawn EP0111408A1 (de) 1982-12-02 1983-12-01 Lautsprechergehäuse

Country Status (1)

Country Link
EP (1) EP0111408A1 (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2176370A (en) * 1985-05-31 1986-12-17 Elektroakusztikai Gyar Loudspeaker, preferably sound column or horn loudspeaker
GB2222744A (en) * 1988-09-13 1990-03-14 B & W Loudspeakers Improvements in and relating to loudspeaker enclosures
FR2653630A1 (fr) * 1989-10-23 1991-04-26 Scotto Di Carlo Gilles Structure d'enceinte acoustique.
WO1991020162A1 (en) * 1990-06-19 1991-12-26 Canon Research Centre Europe Limited Speaker for use in a sound output system
EP0505344A1 (de) * 1991-03-19 1992-09-23 Ivan Schellekens Klangwiedergabevorrichtung ohne mechanische Intermodulation- verzerrung
FR2679095A1 (fr) * 1991-07-09 1993-01-15 Sohn Tong Hoon Systeme de haut-parleurs avec traitement d'onde acoustique reproduite.
FR2687268A1 (fr) * 1992-02-06 1993-08-13 Colin Olivier Enceinte acoustique omnidirectionnelle et procede de fabrication.
FR2688971A1 (fr) * 1992-03-17 1993-09-24 Almonacid Thyerrie Coffrets d'enceintes acoustiques a haute rigidite specifique.
GB2290919A (en) * 1994-06-21 1996-01-10 Jonathan Gregory Michael White A filling for loudspeakers and loudspeaker stands
WO1999013681A2 (en) * 1997-09-05 1999-03-18 1... Ipr Limited Aerogels, piezoelectric devices, and uses therefor
EP1022928A2 (de) * 1999-01-21 2000-07-26 Fenson & Company Limited Vorrichtung und Verfahren zur Tonqualitätsverbessurung von Lautsprechern
US7641954B2 (en) 2003-10-03 2010-01-05 Cabot Corporation Insulated panel and glazing system comprising the same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2334259A1 (fr) * 1975-12-01 1977-07-01 Art Acoustique Appliquee Nouvelle enceinte acoustique
US4044855A (en) * 1974-11-01 1977-08-30 Sansui Electric Co., Inc. Loudspeaker device
US4127751A (en) * 1975-11-27 1978-11-28 Pioneer Electronic Corporation Loudspeaker with rigid foamed back-cavity

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4044855A (en) * 1974-11-01 1977-08-30 Sansui Electric Co., Inc. Loudspeaker device
US4127751A (en) * 1975-11-27 1978-11-28 Pioneer Electronic Corporation Loudspeaker with rigid foamed back-cavity
FR2334259A1 (fr) * 1975-12-01 1977-07-01 Art Acoustique Appliquee Nouvelle enceinte acoustique

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENTS ABSTRACTS OF JAPAN *
PATENTS ABSTRACTS OF JAPAN, vol. 6, no. 222 (E-140)[1100], 6th November 1982 & JP - A - 57 127 396 (SANYO DENKI K.K.) 07-08-1982 *

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2176370A (en) * 1985-05-31 1986-12-17 Elektroakusztikai Gyar Loudspeaker, preferably sound column or horn loudspeaker
GB2222744A (en) * 1988-09-13 1990-03-14 B & W Loudspeakers Improvements in and relating to loudspeaker enclosures
FR2653630A1 (fr) * 1989-10-23 1991-04-26 Scotto Di Carlo Gilles Structure d'enceinte acoustique.
WO1991020162A1 (en) * 1990-06-19 1991-12-26 Canon Research Centre Europe Limited Speaker for use in a sound output system
EP0505344A1 (de) * 1991-03-19 1992-09-23 Ivan Schellekens Klangwiedergabevorrichtung ohne mechanische Intermodulation- verzerrung
BE1004807A3 (nl) * 1991-03-19 1993-02-02 Schellekens Ivan Het weergeven van geluid zonder mechanische intermodulatievervorming.
FR2679095A1 (fr) * 1991-07-09 1993-01-15 Sohn Tong Hoon Systeme de haut-parleurs avec traitement d'onde acoustique reproduite.
FR2687268A1 (fr) * 1992-02-06 1993-08-13 Colin Olivier Enceinte acoustique omnidirectionnelle et procede de fabrication.
FR2688971A1 (fr) * 1992-03-17 1993-09-24 Almonacid Thyerrie Coffrets d'enceintes acoustiques a haute rigidite specifique.
GB2290919A (en) * 1994-06-21 1996-01-10 Jonathan Gregory Michael White A filling for loudspeakers and loudspeaker stands
GB2290919B (en) * 1994-06-21 1998-08-19 Jonathan Gregory Michael White Loudspeakers
WO1999013681A2 (en) * 1997-09-05 1999-03-18 1... Ipr Limited Aerogels, piezoelectric devices, and uses therefor
WO1999013681A3 (en) * 1997-09-05 1999-08-05 1 Ipr Limited Aerogels, piezoelectric devices, and uses therefor
US6677034B1 (en) 1997-09-05 2004-01-13 1 . . . Limited Aerogels, piezoelectric devices, and uses therefor
EP1022928A2 (de) * 1999-01-21 2000-07-26 Fenson & Company Limited Vorrichtung und Verfahren zur Tonqualitätsverbessurung von Lautsprechern
EP1022928A3 (de) * 1999-01-21 2002-11-27 Fenson & Company Limited Vorrichtung und Verfahren zur Tonqualitätsverbessurung von Lautsprechern
US7641954B2 (en) 2003-10-03 2010-01-05 Cabot Corporation Insulated panel and glazing system comprising the same

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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AK Designated contracting states

Designated state(s): BE DE FR GB IT NL

17P Request for examination filed

Effective date: 19841029

STAA Information on the status of an ep patent application or granted ep patent

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18W Application withdrawn

Withdrawal date: 19851203

RIN1 Information on inventor provided before grant (corrected)

Inventor name: BANK, GRAHAM