EP1022928A2 - Apparatus for and a method of improving the sound quality of loudspeakers - Google Patents
Apparatus for and a method of improving the sound quality of loudspeakers Download PDFInfo
- Publication number
- EP1022928A2 EP1022928A2 EP00300282A EP00300282A EP1022928A2 EP 1022928 A2 EP1022928 A2 EP 1022928A2 EP 00300282 A EP00300282 A EP 00300282A EP 00300282 A EP00300282 A EP 00300282A EP 1022928 A2 EP1022928 A2 EP 1022928A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- shell
- sound
- absorbing material
- sound absorbing
- loudspeakers
- 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- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims description 5
- 239000011358 absorbing material Substances 0.000 claims abstract description 17
- 239000000463 material Substances 0.000 claims abstract description 9
- 230000004888 barrier function Effects 0.000 claims description 6
- 239000006261 foam material Substances 0.000 claims description 4
- 239000010410 layer Substances 0.000 description 9
- 239000006260 foam Substances 0.000 description 6
- 230000008901 benefit Effects 0.000 description 3
- 238000013016 damping Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000002745 absorbent Effects 0.000 description 2
- 239000002250 absorbent Substances 0.000 description 2
- 239000011093 chipboard Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000011514 reflex Effects 0.000 description 2
- 229920000877 Melamine resin Polymers 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 229920005830 Polyurethane Foam Polymers 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000010438 granite Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 239000011496 polyurethane foam Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000010454 slate Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Images
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 apparatus for and a method of improving the sound quality of loudspeakers.
- loudspeakers are manufactured including electrostatic, magnetic film types and moving coil cones or domes mounted into open baffles, infinite baffles (closed box types), reflex loaded infinite baffles and transmission line type enclosures.
- the drive units typically consist of two or more moving coil type drive units each optimised to give uniform output over a limited frequency range, an electrical crossover being used to divide the incoming electrical signals to the appropriate drive unit.
- the drive units are mounted in an enclosure, commonly referred to as a cabinet and typically made of wooden panels, chipboard or medium density fibreboard (M.D.F.).
- the purpose of the enclosure is to prevent the out of phase sound emitted from the rear of the drive unit from cancelling that from the front whilst providing a correct acoustic loading to the rear of the drive unit for optimum performance.
- the drive unit imparts vibrational energy to the cabinet from frame reaction to the vibrating cone and from coincident sound energy emitted from the rear of the drive unit. This results in vibration of the cabinet walls causing unwanted sound to be emitted.
- the panel walls typically exhibit a series of resonances whose output may only be a few decibels below of that of the frontal or drive unit output. As the panels have mass their resonance may continue for several milliseconds after excitation. The overall effect of this is to reduce system and sound clarity, dynamic definition and accuracy.
- the present invention seeks to overcome these problems whilst offering the additional benefit of being retrofittable to existing loudspeaker systems.
- apparatus for improving the sound quality of loudspeakers comprising a rigid shell having sound absorbing material on its internal surface, the shell being adapted to fit over a loudspeaker enclosure and the front of the shell being open or substantially open or being covered by material which permits sound to pass therethrough in an undistorted manner.
- a method of improving the sound quality of loudspeakers comprising the steps of fitting apparatus according to the first aspect of the invention over a loudspeaker enclosure.
- apparatus for improving the sound quality of loudspeakers comprises a rigid shell 10 having a rear wall, two side walls 11 and 12, a top wall 13 and a base 14 all internally lined with sound absorbing material 15.
- the front of the shell is open but this could be covered with a removable panel of material which permits sound to pass therethrough in an undistorted manner.
- the shell 10 is adapted to fit over an existing loudspeaker enclosure, typically in the form of a cabinet 16, (housing one or more loudspeakers) preferably with a clearance of typically 2 to 3 mm. between the inner surface of the sound absorbing material 15 and the outer surface of the cabinet 16.
- the shell 10 may be mounted on a speaker stand 17 or on the floor.
- a soft foam sealing strip may be used on the inner edge of the shell to form a seal.
- the shell 10 is ideally isolated from the loudspeaker cabinet 16.
- the loudspeaker cabinet 16 will generally be supported on a plurality of support members, such as pins or spikes, upstanding from the base 14 of the shell 10.
- the speaker cabinet could be mounted directly on the base 14 of the shell 10.
- the shell may be coupled to the floor either directly or via a sub-frame/floor spikes as necessary.
- the shell 10 has no base.
- the shell 10 is typically made from panels of wood, M.D.F. or chipboard.
- the sound absorbing material typically comprises a single layer of sound absorbing material, preferably a foam material such as melamine foam, polyurethane foam or polyether foam.
- the sound absorbing material may comprise at least two, and as shown in Figure 2 three, layers 20 of compressible sound absorbing material, and a barrier layer 21 between the or each pair of adjacent compressible layers 20.
- the compressible sound absorbing material 20 is preferably a foam material.
- the innermost foam layer absorbs high frequency sound energy.
- the inner barrier layer minimises the low frequency sound.
- the middle foam layer absorbs vibration of the inner barrier layer.
- the outer foam layer damps any vibration which may occur in the panel to which it is fixed.
- the barrier layer(s) 21 are denser than the compressible sound absorbing material 20 and are typically formed of "dead rubber” sheet or bituminous or lead damping material.
- the particular make up of the absorbent material may be optimised to suit the speaker system.
- An angled or rounded moulding may be fixed to the front edge of the shell 10 adjacent to the drive unit baffle of the loudspeaker. This is to ensure good sound diffraction and to cover the exposed edge of the shell and sound absorbent material whilst imparting additional edge stiffness to the shell panels.
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)
Abstract
Apparatus for improving the sound quality of loudspeakers, comprises a
rigid shell (10) having sound absorbing material (15) on its internal surface. The
shell is adapted to fit over a loudspeaker enclosure (16) and the front of the shell is
open or substantially open or is covered by material which permits sound to pass
therethrough in an undistorted manner.
Description
This invention relates to apparatus for and a method of improving the sound
quality of loudspeakers.
Currently, several types of loudspeakers are manufactured including
electrostatic, magnetic film types and moving coil cones or domes mounted into open
baffles, infinite baffles (closed box types), reflex loaded infinite baffles and
transmission line type enclosures.
Of these, the most popular is the infinite baffle type and its reflex loaded
variant. Commercially, these account for the majority of speakers in use.
Typically, they consist of two or more moving coil type drive units each
optimised to give uniform output over a limited frequency range, an electrical
crossover being used to divide the incoming electrical signals to the appropriate drive
unit. The drive units are mounted in an enclosure, commonly referred to as a cabinet
and typically made of wooden panels, chipboard or medium density fibreboard
(M.D.F.).
The purpose of the enclosure is to prevent the out of phase sound emitted
from the rear of the drive unit from cancelling that from the front whilst providing
a correct acoustic loading to the rear of the drive unit for optimum performance.
In use, the drive unit imparts vibrational energy to the cabinet from frame
reaction to the vibrating cone and from coincident sound energy emitted from the rear
of the drive unit. This results in vibration of the cabinet walls causing unwanted
sound to be emitted. The panel walls typically exhibit a series of resonances whose
output may only be a few decibels below of that of the frontal or drive unit output.
As the panels have mass their resonance may continue for several milliseconds after
excitation. The overall effect of this is to reduce system and sound clarity, dynamic
definition and accuracy.
This form of coloration has posed a challenge to speaker designers for
many years. The use of bracing, damping pads, and rigid floor coupling via spiked
stands has been used to reasonable effect. To advance the art a few specialist
manufacturers have used alternative specialist materials and construction methods for
the enclosure including concrete, mineral loaded resins, honeycomb cored panels,
dense matrix bracing systems, granite and slate panels and high mass lead seismic
damping systems. Whilst effective at reducing coloration and providing substantial
benefits in terms of improved sound quality these enclosures have the disadvantage
of high cost, typically five to fifteen times greater than a conventional enclosure, and
using materials and production processes not ideally suited to mass production.
The present invention seeks to overcome these problems whilst offering the
additional benefit of being retrofittable to existing loudspeaker systems.
According to a first aspect of the present invention there is provided
apparatus for improving the sound quality of loudspeakers, comprising a rigid shell
having sound absorbing material on its internal surface, the shell being adapted to fit
over a loudspeaker enclosure and the front of the shell being open or substantially
open or being covered by material which permits sound to pass therethrough in an
undistorted manner.
Preferred and/or optional features of the first aspect of the invention are set
forth in claims 2 to 7, inclusive.
According to a second aspect of the invention there is provided a method
of improving the sound quality of loudspeakers, the method comprising the steps of
fitting apparatus according to the first aspect of the invention over a loudspeaker
enclosure.
The invention will now be more particularly described, by way of example,
with reference to the accompanying drawings, in which;
Referring now to the drawings, apparatus for improving the sound quality
of loudspeakers, comprises a rigid shell 10 having a rear wall, two side walls 11 and
12, a top wall 13 and a base 14 all internally lined with sound absorbing material 15.
The front of the shell is open but this could be covered with a removable panel of
material which permits sound to pass therethrough in an undistorted manner.
The shell 10 is adapted to fit over an existing loudspeaker enclosure,
typically in the form of a cabinet 16, (housing one or more loudspeakers) preferably
with a clearance of typically 2 to 3 mm. between the inner surface of the sound
absorbing material 15 and the outer surface of the cabinet 16. The shell 10 may be
mounted on a speaker stand 17 or on the floor. A soft foam sealing strip may be used
on the inner edge of the shell to form a seal.
To give optimum performance, the shell 10 is ideally isolated from the
loudspeaker cabinet 16. However, in practice this is difficult to achieve and the
loudspeaker cabinet 16 will generally be supported on a plurality of support members,
such as pins or spikes, upstanding from the base 14 of the shell 10. Alternatively,
particularly with heavy speakers, the speaker cabinet could be mounted directly on
the base 14 of the shell 10. In the case of a floor standing speaker cabinet, the shell
may be coupled to the floor either directly or via a sub-frame/floor spikes as
necessary. Typically, in this case, the shell 10 has no base.
The shell 10 is typically made from panels of wood, M.D.F. or chipboard.
The sound absorbing material typically comprises a single layer of sound
absorbing material, preferably a foam material such as melamine foam, polyurethane
foam or polyether foam. Alternatively the sound absorbing material may comprise
at least two, and as shown in Figure 2 three, layers 20 of compressible sound
absorbing material, and a barrier layer 21 between the or each pair of adjacent
compressible layers 20. The compressible sound absorbing material 20 is preferably
a foam material. In this case, the innermost foam layer absorbs high frequency sound
energy. The inner barrier layer minimises the low frequency sound. The middle
foam layer absorbs vibration of the inner barrier layer. The outer foam layer damps
any vibration which may occur in the panel to which it is fixed.
The barrier layer(s) 21 are denser than the compressible sound absorbing
material 20 and are typically formed of "dead rubber" sheet or bituminous or lead
damping material. The particular make up of the absorbent material may be
optimised to suit the speaker system.
An angled or rounded moulding (not shown) may be fixed to the front edge
of the shell 10 adjacent to the drive unit baffle of the loudspeaker. This is to ensure
good sound diffraction and to cover the exposed edge of the shell and sound absorbent
material whilst imparting additional edge stiffness to the shell panels.
The use of this system typically reduces cabinet wall sound output by 20
to 30 decibels whilst dramatically reducing the effects of panel resonance resulting
in a substantial improvement in sound quality at a relatively low cost with the added
benefit of being retrofittable to existing systems.
Claims (8)
- Apparatus for improving the sound quality of loudspeakers, comprising a rigid shell (10) having sound absorbing material (15) on its internal surface, the shell being adapted to fit over a loudspeaker enclosure (16) and the front of the shell being open or substantially open or being covered by material which permits sound to pass therethrough in an undistorted manner.
- Apparatus as claimed in claim 1, wherein the shell comprises a rear wall, two side walls (11,12) and a top wall (13) all lined or substantially lined with sound absorbing material (15).
- Apparatus as claimed in claim 2, wherein the shell further comprises a base (14).
- Apparatus as claimed in claim 3, wherein the base is also lined or substantially lined with sound absorbing material (15).
- Apparatus as claimed in any one of the preceding claims, wherein the sound absorbing material (15) is a compressible foam material.
- Apparatus as claimed in any one of the preceding claims, wherein the sound absorbing material comprises at least two layers (20) of compressible foam material with a barrier layer (21) therebetween.
- Apparatus as claimed in claim 6, wherein the barrier layer (21) is denser than the compressible sound absorbing material (20).
- A method of improving the sound quality of loudspeakers, comprising the step of fitting the apparatus of any one of the preceding claims over a loudspeaker enclosure (16).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB9901187.6A GB9901187D0 (en) | 1999-01-21 | 1999-01-21 | Apparatus for and a method of improving the sound quality of loudspeakers |
| GB9901187 | 1999-01-21 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP1022928A2 true EP1022928A2 (en) | 2000-07-26 |
| EP1022928A3 EP1022928A3 (en) | 2002-11-27 |
Family
ID=10846158
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP00300282A Withdrawn EP1022928A3 (en) | 1999-01-21 | 2000-01-17 | Apparatus for and a method of improving the sound quality of loudspeakers |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP1022928A3 (en) |
| GB (2) | GB9901187D0 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202799035U (en) * | 2012-08-28 | 2013-03-13 | 赵浩波 | Absorbable fixing structure for speaker with built-in power supply |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4313521A (en) * | 1980-06-16 | 1982-02-02 | Rodden M Raymond | Speaker housing |
| EP0111408A1 (en) * | 1982-12-02 | 1984-06-20 | Celestion International Limited | Loudspeaker cabinets |
| HU193767B (en) * | 1985-05-31 | 1987-11-30 | Elektroakusztikai Gyar | Loudspeaker, favourably sound column or horn loudspeaker |
| DE4000132A1 (en) * | 1990-01-04 | 1991-07-11 | Prodan Hans Joachim | Loudspeaker enclosure - lined with convex sound reflecting and absorbing panel(s) prevents unwanted resonance(s) |
| US5194701A (en) * | 1991-09-11 | 1993-03-16 | N.P.L. Ltd. | Speaker structure |
-
1999
- 1999-01-21 GB GBGB9901187.6A patent/GB9901187D0/en not_active Ceased
-
2000
- 2000-01-17 EP EP00300282A patent/EP1022928A3/en not_active Withdrawn
- 2000-01-17 GB GB0000834A patent/GB2346030A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP1022928A3 (en) | 2002-11-27 |
| GB0000834D0 (en) | 2000-03-08 |
| GB9901187D0 (en) | 1999-03-10 |
| GB2346030A (en) | 2000-07-26 |
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| AKX | Designation fees paid | ||
| REG | Reference to a national code |
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| 18D | Application deemed to be withdrawn |
Effective date: 20030528 |