GB2435206A

GB2435206A - Vibration isolating loudspeaker foot

Info

Publication number: GB2435206A
Application number: GB0602998A
Authority: GB
Inventors: John Kalli
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-02-15
Filing date: 2006-02-15
Publication date: 2007-08-22
Also published as: GB0602998D0; GB0611196D0; GB2435207A

Abstract

A vibration and noise absorbing foot for a loudspeaker has a compliant, damping layer 16 disposed between a ground engaging member 17,19 and a member 14 forming a point of attachment with the supported speaker. The foot may take various forms [Figures 7-11] and may have either rod 14 or an adhesive contact surface to attach the foot to a speaker enclosure. The foot may be adjustable in height, e.g. by using a threaded support 19, screw 18 and nut 15. In one embodiment, the damping layer separates the rigid threaded rod 14 and threaded screw 18. The layer is compliant and equally distributes the speaker's weight to all feet for improved stability.

Description

A Patent Specification

Loudspeaker feet and loudspeaker support equipment feet This invention relates to feet that isolate and stabilise speakers and loudspeaker support furniture for improved sound reproduction. Also this invention provides ease in use for levelling and positioning a speaker with less need to re-calibrate should they be relocated, and are simple to fit and suitable for any surface.

BackEround The performance of a speaker is compromised by its support arrangements. Firstly a low degree of feet isolation from noise and vibration energy will degrade the speakers' performance. Audio energy from the speaker will cause vibration of the room environment and this will enter the speaker body via its supports as noise to the acoustic signal the listener will hear. A speaker with spiked or coned feet (manufactured with various profiles, sizes and materials), offer a poor barrier to noise and vibration. Spikes and cone feet are honed to a point and offer isolation by minimising the contact surface, however they offer no additional damping other than that provided by the body of the spike or cone. Spike and cone feet rely upon penetration of the floor or furniture surfaces to effect stability, thereby forming a linked or rigid structure with no brake or discontinuity to the vibration and noise energy that is able to propagate feely. In a trial (reference -Articles on vibration by Keith Howard in the July and August 2002 issues of Hi Fi News), measurements of vibration energy of a speaker stand when playing a speaker fitted with cones produced vibration in the stand of over one hundred times greater than if the cones were replaced with small rubber feet, this effect is audible to the user as a reduction in clarity of the speaker. This invention is speaker feet with a dampened section to increase isolation to vibration/noise energy. This invention has a compliant layer to separate the rigid structural parts to form a discontinuity to the path of noise/vibration energy and improve isolation. This invention is feet decoupled from the support surfaces for improved isolation to noise/vibration energy. This invention is feet that enhance speaker sound reproduction.

Feet such as spikes and cones are rigid structures and are further compromised by instability as a gap, such as an uneven floor is directly transferred to instability in the speaker under dynamic conditions, for example when the speaker is operating. Supports are only stable when the weight is equally exerted on each support, with rigid feet such as spike/cone this is a critical distance, any higher and the speaker raises against some or all the other feet producing further spaces, any shorter and there is a gap both of which leave the speaker unstable. In practice they are difficult to use and rely on the tips penetrating the contact surface to effect stability, however direct coupling to the surroundings increases noise entering the speaker, or should the floor or surface be impenetrable the speaker will remain unstable and even microscopic movement will reduce the accuracy of the reproduced sound audible to the user. This invention has a compliant part in the feet to distribute the weight of the speaker evenly to all supports and improve stability and the performance of the speaker.

For example, a concrete or stone floor with heavy or thick carpet and underlay will not be enable the use of rigid feet such as spikes/cones that will for the reasons discussed have compromised stability.

This invention will use a spike or cone support section to pierce the flexible coverings to contact the structure beneath and has compliant parts to remain stabile.

Another apphcation is use on polished real wood, laminate, stone, tiled or linoleum floors or veneered furniture surfaces that are scratched or damaged by feet such as spikeslcones. Metal dimpled discs are available to protect the surfaces with such feet however there is a similar instability problem described above as each foot must perfectly span the support gap, and cannot rely on penetration for stability, any gap here, under dynamic playing conditions will induce microscopic rocking, a problem for speaker performance. An alternative embodiment of this invention has dome or sphere supports with additional compliant sections within the feet for stability and are suitable for hard floors or furniture surfaces. A worst-case scenario being a light speaker located on a veneer or highly polished surface, this invention has compliant contact surfaces offering stability without damage to finishes.

Speakers need to be set-up for best results using sound trials of the speakers in various locations in the room to find the optimum position with the best "sound balance", even if the speaker manufacture provides specific set-up guidelines. The problem with rigid supports is when the speaker is moved even by small amounts the feet require re-calibration, also this may mean physically liffing the whole speaker to re-site it and avoid damaging the floor; either way, it is awkward and time consuming and there is always a possibility of damaging the surface finishes.

This invention is easy to use, the compliant part of the feet accommodate changes in surface profiles without re-adjusting the height of the feet to secure stability. Also this invention is de-coupled from the support surface and enable minimal lifting of the speaker for positioning and set-up required to achieve the best sound balance for the speaker.

There are also "soft" feet for speaker support, made from materials such as polymer or rubber however these cannot level the speaker nor allow the user to adjust the feet height to direct the speaker up or down when canying-out the sound trials needed to obtain the best performance.

Speakers are designed to project a "soundstage" or "sweet point" in the field of listening, based upon assumptions about typical room sizes; and use of time-alignment or phase alignment theory of the projected sound waves to ensure coherence. For example, a dynamic speaker type has an array of drivers operating in fixed frequency ranges (e.g. high, middle and low driver units) and this technique is used by the designer to position the drivers in the vertical plane of the speaker such that the sound waves are coherent at an assumed listening distance to the user, and appears to form a "soundstage" or "sweet point". There is a time-alignment design requirement to adjust the height of the feet and playing angle when setting-up the speaker to ensure best sound perfonnance.

Also, speakers are directional depending on a greater or lesser degree upon the type of speaker and the design used, for example they may concentrate sound in a conical form like the light from a torchlight. A further requirement to adjust the feet height and playing angle depend upon the directional characteristics of the speaker, the users personal preferences, the main listening location and the effect of the rooms' acoustics to get the best performance from the speaker.

This invention has height adjustment screws to control of the angle of the speaker's vertical playing field and enable the user to set-up the speaker to it's optimum performance.

This invention also has connecting thread rods to fit directly to the speaker's nut fixings, or adhesive fixing surfaces, that are easy to install.

In describing the background of this invention for speakers the same advantages are gained for loudspeaker furniture support equipment, such as speaker stands, plinths, and wall brackets and all speaker types such as dynamic, electrostatic, horn, planer-magnetic, and sub-woofer.

Statement of invention

The essential features of this invention are feet for all types of loudspeaker and loudspeaker furniture or support equipment, such as speaker stands, plinths, and wall brackets that are-i) With a dampened section to increase isolation to vibrationlnoise energy, and enhance sound reproduction.

ii) With a compliant layer to separate the rigid structural parts to form a discontinuity to the path of noise/vibration with improved isolation and sound reproduction.

iii) With a compliant part to distribute the weight of the speaker evenly to all supports and improve stability and the performance of the speaker.

Advanta2es The advantaged offered by this invention are speaker feet that are-i) De-coupled from the support surface with better isolation and improved performance.

ii) Compliant and mould to the profile of the floor or support furniture require less re-calibration and set-up the speaker.

iii) De-coupled from the support surface and enable minimal lifting of the speaker for positioning and set-up required to achieve the best sound balance for the speaker.

iv) De-coupled from the support surface offers suitable support to any surface.

v) Height adjustable for levelling or tilting of the speaker to optiniise the playing angle to match the speaker design specification, room acoustics and preferences of the user.

vi) Height adjustable for stability.

vii) Easy to fit with either threaded rods to connect directly to the speaker's nut fixings, or supplied with adhesive fixing surfaces.

Introduction to drawings

Figure 1: Shows spike and cone feet used with a speaker and speaker stand arrangement that are affected by instability and isolation problems.

Figure 2: Is a section view of a spike foot forced through carpet and underlay and into the timber floor beneath that compromise isolation of the speaker.

Figure 3: Shows "soft" feet with a floor standing speaker to illustrate the need to adjust the feet height, that otherwise compromise performance of the speaker.

Figure 4: Shows a floor standing speaker to illustrate how the playing angle of the speaker will compromise the time-alignment performance of the speaker and compromise the coherence of the sound received by the listener.

Figure 5: Shows how subjective auditioning is used to locate the speakers to achieve the best sound for a type of speaker, room acoustics and personnel preferences.

Figure 6: Illustrates a speaker with a playing angle that is adjusted off-centre to th.e listenmg position to obtain the best sound balance for the user.

Figure 7: Shows an embodiment of this invention.

Figure 8: Is an alternate embodiment of this invention.

Figure 9: Is a further alternate embodiment of this invention.

Figure 10: Is a further alternate embodiment of this invention with a large diameter screw arrangement stronger than the earlier feet illustrated in figures 7 to 9.

Figure 11: Is a further alternate embodiment of this invention with a large diameter screw arrangement stronger than the earlier feet illustrated in figures 7 to 9.

Description of drawings

Figure 1, illustrates supports spikes 3 and cones 4 that compromise the performance of speaker I and speaker stand 2. These feet do not have additional dampening and they rely on penetration of the surface to effect stability and precise adjustment of the height. The former forms a linked or coupled structure and is a poor barrier to vibration and noise energy. The latter require the feet to sit without penetration of the surface and the height of each foot becomes critical, any shorter or oversize will result in unequal distributed pressure between the feet. This instability will allow movement such as rocking when the speaker operates and the tiniest of movements will result in noise and vibration obscuring the sound performance.

Figure 2 is a cross-section of one spiked foot 3, shown forced through the floor coverings of carpet and underlay 5 and into the timber floorboards 6 below to secure stability of the speaker 1. A link or couple is made between the speaker and the floor and introduce noise and vibration energy mto the speaker system, a deteriorative effect to sound reproduction.

Figure 3 has "soft" feet 7 support for a floor standing speaker 1 and either due to an uneven floor surface or the centre of gravity of the speaker, the speaker is out of level 8. "Soft" feet cannot level the speaker nor allow the user to adjust the feet height to direct the speaker up or down when carrying-out the sound trials needed to obtain the best performance.

Figure 4 illustrates the requirement of the user to adjust the height of the support feet, here a floor speaker I designed to time-alignment parameters has a set of three drivers 9 in terraced positions within the speaker body to optimise the coherence of the sound waves 10 heard by the user. The speaker 1 however, is not vertical ii and the travel path of the sound waves 10 are increased by the relative distances 12 that destroys the integration of the sound, the "soundstage" or "sweet spot" of the speakers' performance, Figure 5 shows how subjective auditioning (verified by in-room sound measurements) is used to locate the speakers I and in practice require listening in different positions to achieve the best sound, for example relative to walls -shown by arrowed dimensions.

The ease of handling and set-up of the speaker depends upon support arrangements and feet that are easy to use, with minimal re-calibration, are vital for this exercise.

Speakers to a greater or less of extent are directional and focus the sound differently. Figure 6 is a stand-mounted loudspeaker 1 with strong directional characteristics and is shown positioned off axis, that is off the direct line of the sound wave 11. The focus of sound from the tweeter driver 9 forms a conical shape 13 above the listening area that would otherwise appear too prominent or "bright" had the speaker been directed at the listener.

Figure 7 is an embodiment of this invention with a connecting threaded rod 14 for easy fitting to the speakers' feet nuts. A locking nut 15 with the threaded rod 14, adjusts and secures the speaker height. The damping material layer 16 provides isolation of the feet and separates the rigid parts, that is, the threaded rod 14 from the support feet 17 and also increases isolation. The damping layer 16, is compliant and equally distributes the speakers' weight to all the feet for improved stability and performance of the speaker. The support 17 has a domed profile and is bonded to the damping layer 16.

Despite further development and testing data to date, this arrangement would suggest its suitability with larger speakers on polished real wood, laminate, stone, tile or thin floor coverings such as linoleum or carpet.

Figure 8 is an alternate embodiment of this invention with threading rod 14, and locking nut 15, and with the damping layer 16, but here it is extended to form the support dome 17, possibly with a combination of materials moulded to form a casing of the domed foot support 17. This offers the advantages described for the figure 7 feet having improvements in isolation and stability, plus the ease of use and set-up.

Despite further development and testing data to date, this arrangement would suggest its suitability with smaller/mediulTi sized speakers, for example a stand mount speaker or small floor standing speaker and with a good degree of protection to surfaces, for example use with veneered furniture.

Figure 9 is a further alternate embodiment of this invention, with the damping layer 16 is screwed with the threaded rod 14 to secure the foot to the speaker. The damping layer 16 also separates the threaded rod 14 from the locking nut's screw 18 forming a compliant layer for improved isolation and stability. The height of the feet extends or recedes into the support spike 19 having a threaded core.

Despite further development and testing data to date, this arrangement would suggest its suitability with floors with heavy/thick carpet and underlay coverings whether there is a timber, concrete floor structure beneath.

Figure 10 is a further alternate embodiment of this invention, as with the foot in figure 9 this arrangement is with the damping layer 16 uppermost and locks the foot to the speaker using screw 14. Here the threaded screw 18 has a large diameter and a offers a stronger foot arrangement those feet illustrated in figures 7,8 and 9, the height adjusted by the threaded support 19 and the screw 18 and locked with nut 15.

Despite further development and testing data to date, this arrangement would suggest its suitability for a wide variety of applications both speaker/furniture and support surfaces.

Figure his a further alternate embodiment of this invention, as with the foot in figure 10 has the damping layer 16 uppermost however here the damping layer 16 is recessed in the screw body 18.

The height is adjusted by the threaded support 19 and the screw 18, a locking nut fits on the screw 18 but not shown here.

The feet of figures 9, 10 and 11 have a further alternate embodiment of this invention by replacing the threaded bar 14 by an adhesive contact surface on the upper face of the damping layer 16 to enable ease of use for a wide range of speaker and speaker support equipment.

Claims

The Claims 1 Feet for all types of loudspeaker, such as dynamic,

electrostatic, horn, planer-magnetic, and sub-woofer loudspeaker, and loudspeaker furniture or support equipment, such as speaker stands, phnths, and wall brackets.

2. Loudspeaker feet according to claim 1, with a dampened section to increase isolation from vibration and noise energy.

3. Loudspeaker feet according to claim 1, with a compliant layer to separate the rigid structural parts of the feet and form a discontinuity to the path of noise/vibration and improve isolation characteristics of the support.

4. Loudspeaker feet according to claim 1, with a compliant part to distribute the weight of the supported unit/s evenly to all supports and improve stability.