GB2350965A

GB2350965A - Loudspeaker cabinet and microphone housing internal damping system

Info

Publication number: GB2350965A
Application number: GB9913471A
Authority: GB
Inventors: Stefan Gamble
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-06-10
Filing date: 1999-06-10
Publication date: 2000-12-13
Anticipated expiration: 2019-06-10
Also published as: GB2350965B; GB9913471D0

Abstract

The system damps acoustic and energy pulses 43 originating from a source such as a driver unit 42 in a loudspeaker cabinet 41, or the reflected second generation signals resulting from the acoustics surrounding a recorded source. There is provided a suitably match weight 44 which is freely suspended by means of resilient elastic sandwiching, chosen to approximate to the generated energies 43 required damping. When these damping masses 44 are affected by an energy source 43 they will resonate 48 in harmony and absorb free acoustic and air pulse energy, converting it into heat, which may be dissipated by means of controlled air movement or transferred to another plate and so on.

Description

2350965 LOUDSPEAKER CABINET AND MICROPHONE HOUSING INTERNAL DAMPING SYSTEM

This invention relates to the damping of air and sound pressure pulses in noise and air flow control in loudspeaker cabinets and microphone housings.

Currently microphone housings and their damping is almost non existent, while all non-electronic loudspeaker damping techniques have concentrated on reflection or wadding resistance damping.

In general these systems have proven relatively ineffective in that suitably reflective materials have to reflect energy at an angle of less than 45 degrees to work best, and by varying amounts simply transmit noise and pressure pulses which strike at any angle more than 45 degrees, while resistance damping must be inordinately and impractically thick to have much effect. Increased or decreased mass simply shifts a natural resonance frequency but does not remove it. Standing waves are emphasised while octave related phasing is decreased or boosted.

According to the present invention there is provided a suitably matched weight of freely elastically and resiliently suspended damping mass or multiples thereof, chosen to approximate to the generated sound and pressure 1 energy pulse required damping which is emitted from the generating device. In a loudspeaker application. the damping mass should be approximately equal to the driver's rear acoustic and pneumatic sound level.

Provided this matched mass is freely suspended by means of resilient and elastic sandwiching, the mass will vibrate in harmony with the acoustic and pressure pulse generating source's energy output, thus causing a mechnanical, air compliance energytoheat conversion and resulting in a lowering of environment induced standing waves and octave related phase cancellation or boosting.

Both standing waves and phase decibel changes are undesirable. The aim is to create a clean first generation signal, constant pitch or quietness with rapid past signal decay.

Through harmonic resonating damping and air compliance this system will attenuate acoustic and pressure standing waves inside a cabinet, resulting in less second generation rear reflected energy to transmit through the cabinet or reflect back through the driver cone's rear face.

This will also produce less decibel and frequency fluctuation of standing waves and further define problem frequency bands that may be easier dealt with.

When used in a loudspeaker cabinet application, the harmonic 21 1 resonance system's greater usable cleaner decibel saturation levels allows for a smaller box with greater sound absorbtion and insulation properties, or a higher, cleaner decibel capacity from a same sized box.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 shows in cross section loudspeaker driver rear face, emitted energy, resonating mass/s and the elastic resilient suspension medium.

Referring to the drawing figure 1 shows the loudspeaker enclosure (41) with the driver unit (42) and emitted energy (43) firing into the freely elastically suspended (50) inatched-mass damping material/s (44). The air pressure pulse (43) will cause movement (48) in the primary matched damping mass (44) proportionately to the driver cone movement (49), resulting in energy being absorbed and converted into heat through air compliance. The moving or resonating (48) damping mass (44) constantly changes the internal distances between the plates (44) and boundary walls (45) which reduces the build up of standing waves and damps any that may occur.

3 Referring to the drawing figure 1, surplus acoustic and pneumatic energy resulting from the movement (48) of the first damper plate will be radiated at a further reduced level (51) into the secondary damper plates (44) at continuously lower levels.

By these means of mass and air compliance damping unwanted energy can be progressively and controllably reduced and delayed for driver/port phasing purposes.

If i - i

Claims

1. Where a suitably chosen mass is freely suspended by means of a resilient elastic sandwiching and used to damp unwanted acoustic and pneumatic energies by means of harmonic resonance movement inside any loudspeaker cabinet or microphone housing enclosure.

2. As in claim 1 but with additional variable damping materials and masses chosen to suit multiple acoustic frequencies, decibel levels and variable pressure pulse damping.

3. As in claim 1 and claim 2 but with the multiplication of identical damping masses to gradually reduce decibel levels and pressure pulse effects.

4. As in claim 1 and claim 2 but with progressively varying damper plate masses.

5. As in claims 1 and 2 but with the damping plates and/or their mass weighting and/or their spacing and/or their suspension resilience proportioned at the ratios of 1/1.25/1.6 or multiples thereof.

6. As in claim 1,2,3 and 4 but with frequency relief ports cut into the damper plates of 1/1.25/1.6 ratios or multiples thereof.

7.As inc claim 1,2,3,4,5 and 6 but with each plate surface treated to accept and/or reflect energy.

8. As in claim 1,2,3,4,5,6 and 7 but applied to noise damping panels, wall treatments for insulation and isolation purposes.

9. Harmonic weight mass and resistance resonance damping substantially 1 as described herein with reference to figure 1 and figure 2 in the accompanying drawings.

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