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KEF's New Tech is Real

Soniclife

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#81
not exactly new tech (~2017) and also not Kef's technology. Kef's speakers might be the first commercial application, though. Nevertheless, pretty cool stuff.
A few bits from the AMG site & Darko's article that I find most interesting:

3-4" thickness should be ok for most rooms. And those mazes look kinda cool, might have a good WAF too.
Could also be perfect if you have a boiler room or other noisy house installations. Or for a dedicated cinema room. Assuming of course that they do not cost more than the house.


IIUC, it should be possible to build user-customizable absorber panels. I.e. one can adapt the panels to his own room conditions/frequencies by changing the 'maze' structure.
That would be a very good application, we don't want truly anechoic in our rooms, but inch thick panels that work much better than existing panels would be very welcome.
 

hardisj

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#82
Maybe I'm alone on this, but the "material" tag is misleading, at least to me. When I hear the word "material" I think of metal, cloth, foam, etc. Things that make up something. When I hear "material" used in the acoustic sense, I think of foam, fiberglass... typical absorption stuff. To me this is a (series of) Helmholtz resonator rather than the traditional "material" (cloth, foam, etc). And I think, at least to some, that may be why there is the initial scoff... because the first thought I had was "Oh, sure, kef put some foam in their cabinets that is super great". But when you look in to what it actually is and find out, then it seems more plausible and not just some audiophoolery/marketing.
 

Vini darko

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#83
Maybe I'm alone on this, but the "material" tag is misleading, at least to me. When I hear the word "material" I think of metal, cloth, foam, etc. Things that make up something. When I hear "material" used in the acoustic sense, I think of foam, fiberglass... typical absorption stuff. To me this is a (series of) Helmholtz resonator rather than the traditional "material" (cloth, foam, etc). And I think, at least to some, that may be why there is the initial scoff... because the first thought I had was "Oh, sure, kef put some foam in their cabinets that is super great". But when you look in to what it actually is and find out, then it seems more plausible and not just some audiophoolery/marketing.
Agreed thats exactly what thought at first. I figured they put some no-res type stuff in there.
 

Wes

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#84
KEF should have used the name "para' and then followed up with "meta" - the last version could be "para"

then start over with the LS55 or 60
 

thewas_

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#85
A metamaterial (from the Greek word μετά meta, meaning "beyond" and the Latin word materia, meaning "matter" or "material") is any material engineered to have a property that is not found in naturally occurring materials.[3] They are made from assemblies of multiple elements fashioned from composite materials such as metals and plastics. The materials are usually arranged in repeating patterns, at scales that are smaller than the wavelengths of the phenomena they influence. Metamaterials derive their properties not from the properties of the base materials, but from their newly designed structures. Their precise shape, geometry, size, orientation and arrangement gives them their smart properties capable of manipulating electromagnetic waves: by blocking, absorbing, enhancing, or bending waves, to achieve benefits that go beyond what is possible with conventional materials.

Appropriately designed metamaterials can affect waves of electromagnetic radiation or sound in a manner not observed in bulk materials.[4][5][6] Those that exhibit a negative index of refraction for particular wavelengths have been the focus of a large amount of research.[7][8][9] These materials are known as negative-index metamaterials.

Potential applications of metamaterials are diverse and include optical filters, medical devices, remote aerospace applications, sensor detection and infrastructure monitoring, smart solar power management, crowd control, radomes, high-frequency battlefield communication and lenses for high-gain antennas, improving ultrasonic sensors, and even shielding structures from earthquakes.[10][11][12][13] Metamaterials offer the potential to create superlenses. Such a lens could allow imaging below the diffraction limit that is the minimum resolution that can be achieved by conventional glass lenses. A form of 'invisibility' was demonstrated using gradient-index materials. Acoustic and seismic metamaterials are also research areas.[10][14]

Metamaterial research is interdisciplinary and involves such fields as electrical engineering, electromagnetics, classical optics, solid state physics, microwave and antenna engineering, optoelectronics, material sciences, nanoscience and semiconductor engineering.[5]

Source: https://en.wikipedia.org/wiki/Metamaterial
 

napilopez

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#86
Yeah, the term metamaterial itself is kind of weird and is definitely PR-friendly but the usage is inline with how I've heard it used before. @hardisj, if you haven't already you might enjoy checking out the KEF whitepaper.

I think it bears seeing just how effective the technology is. Even if the improvement is audibly small, this is pretty awesome to see:

1600983972411.png


That's just for the metamaterial/plastic maze disc itself. When combined with some foam and a waveguide for a rear of the tweeter, the absorption comes to this:

1600984269041.png

Naming aside, KEF set out with an engineering goal and seems to have achieved it completely, so I'm excited to see how they use this tech in the future.
 
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#87
Confused why they seem to have removed RCA inputs from the wireless version. Would RCA to 3.5mm from avr pre-outs be identical to the old RCA to RCA?
 
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#91
@thewas_ Exactly. I've seen a couple of videos from the company they worked with and the idea was exactly that. Plastic disk wouldn't absorb anythin unless you find a way to make it absorb. So it's an artificially added property.
 

Soniclife

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#92
I'd love to see this technology applied in a midrange chamber.
I wonder if they will do this in whatever they replace the Blade or reference line with.

What happens if applied to bass drivers? Do they think they are operating in an open baffle?
 
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#93
I'd love to see this technology applied in a midrange chamber.
With the disk effective to only 600hz, it seems the logical next step is to have the entire surface inside the cabinet walls printed with more and larger 3d labyrinths to absorb lower frequencies. And to bring it to the extreme, every space between the outer cabinet and inner bracing could be filled with 3d meta material cubes filling the whole inner volume.
 

tomtoo

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#94
With the disk effective to only 600hz, it seems the logical next step is to have the entire surface inside the cabinet walls printed with more and larger 3d labyrinths to absorb lower frequencies. And to bring it to the extreme, every space between the outer cabinet and inner bracing could be filled with 3d meta material cubes filling the whole inner volume.
Thats the problem with a metamaterial. To get lower in fr response you have maybe to change a lot?
 

mhardy6647

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#95
KEF should have used the name "para' and then followed up with "meta" - the last version could be "para"

then start over with the LS55 or 60
Or they could just sell out to the Ortho pest products company & be done with it. ;)

1601047997648.png
 

aarons915

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#97
With the disk effective to only 600hz, it seems the logical next step is to have the entire surface inside the cabinet walls printed with more and larger 3d labyrinths to absorb lower frequencies. And to bring it to the extreme, every space between the outer cabinet and inner bracing could be filled with 3d meta material cubes filling the whole inner volume.
You can't absorb in the range of the port though or you would have no port output. I don't see the lower frequencies as much of a problem really, most problems in speakers are above the 600Hz range.
 
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#98
You can't absorb in the range of the port though or you would have no port output. I don't see the lower frequencies as much of a problem really, most problems in speakers are above the 600Hz range.
Yeah, you'd want to avoid blocking the port. This is above my pay grade, but the labyrinth volume could culminate in a widening at the end, leading to the port opening with enough internal volume for air flow, but not looking like a traditional straight tube on the inside.

You might be right on most problems being above 600hz. I'd think you'd want to absorb any part of the fr with the potential to re-rediate back through the cone, as it is thin and not a very good acoustic barrier.
 

Mnyb

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#99
In lower frequency the box is small compared to wavelengths , can it be considered just an “air spring” and part of the driver ? Thus damping in lower frequency is just more resistance? Makes the cab behave like a bigger box ?
 
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