5 ms·

Metamaterial Absorber for Loudspeaker Enclosures (2020)

33 points by Kaibeezy 4y ago

Kaibeezy 4y ago
Metamarketing Emitter for Loudspeaker Sales? Fig. 6 looks a lot like I imagined Culture ships. Dense complex ridge-and-channel waveguides.
dmos62 4y ago
Getting a 404. https://web.archive.org/web/20220525085742/https://www.aes.org/tmpFiles/elib/20220525/20758.pdf https://web.archive.org/web/20220525085742/https://www.aes.o...
- AlbertoGP 4y ago
  Same here, an unambiguous 404. Thanks for the Archive link, I was curious about Kaibeezy’s reference to Culture ships. Now, as I write this you posted 1 hour ago, and the story submission was 3 hours ago, therefore the file would have been taken down during that two hour window. Curiously, buro9’s comment, which seems to imply that they did look at the document, was 38 minutes ago. Maybe they took a while to read it, and commented some time later? That would put the take-down time to not long before you first reported the 404, assuming buro9 took around half an hour to look at it before commenting. I doubt they got such an increase in requests that they noticed and somehow decided to take it down. Does anyone have an idea what could have happened here?
  - buro9 4y ago
    The correct link is in my comment. I'd read this before, but knew immediately what it was... saw the archive link and remembered where the original was. I think their `browse.cfm` has session identifiers implicit in it (or a referrer check), and all that happen is it worked for the person who posted it but no-one else. Culture ships were all described as ellipsoid were they not? With field management controlling the outer skins.
- aj7 4y ago
  Can only get cover page. Is there something I don’t understand about the mechanicsof web archive?
buro9 4y ago
I knew this was going to be about or by KEF from the title. This is the link to the paper: https://www.aes.org/e-lib/browse.cfm?elib=20758 https://www.aes.org/e-lib/browse.cfm?elib=20758 These are speakers with this: https://uk.kef.com/pages/ls50-meta https://uk.kef.com/pages/ls50-meta And this is the marketing page for the same item as the paper covers: https://uk.kef.com/pages/metamaterial https://uk.kef.com/pages/metamaterial I listened to these speakers... they are good. But I didn't find them "better" than others I listened to in my room (I home auditioned quite a few speaker pairs), a bit too crisp, cold and surgical. That was likely nothing to do with the metamaterial absorption and probably more to do with the way the electronics inside worked. YMMV, listen to them to find out. In the end for me, I opted for far more traditional speakers: near field I have some PSI Audio studio monitors ( https://www.psiaudio.swiss/ https://www.psiaudio.swiss/ ), and for the larger room some Tannoy Eatons ( https://www.tannoy.com/product.html?modelCode=P0DEL https://www.tannoy.com/product.html?modelCode=P0DEL ). I do have some recent KEFs, but they're for the kitchen radio(!). I would be far more interested in this material and approach being taken out of loudspeakers and implemented in transport modes that have high background noise, or in baffles in concert halls (or even cafes!).
- balfirevic 4y ago
  > I have some PSI Audio studio monitors Ouch, those are expensive. Any small studio monitors (4 or 5 inch woofer) you'd recommend in $500-$600 range (per speaker)? I can't really try many out where I live, unfortunately.
  - buro9 4y ago
    Audio is very personal. As a vague hand-wavey thing, humans hear 95% of the same thing (women hear more!) and it's the individual 5% difference that matters. Plus the room you place speakers in matters (lots of hard surfaces in a room that is a box makes a messy sound that bounces around, you have to shape the acoustics to avoid making good speakers sound bad and also to make good speakers sound great), and if the room is large small speakers can disappear and sound small. And of course what you listen to also matters. The PSI Audio are studio monitors... they reveal everything, they're as close to perfect as you can imagine so long as you sit 1m from them (I've been in studios, these sound like being there with the band). But studio monitors reveal all the flaws too. They're not for everyone, in fact they're not far the vast majority of people. I can't really help based on what you asked... room size, music style, how good your ears are, whether you want active (amp built in) or passive (needs an amp), what your usual music source is... these are all the big parameters. But for your budget, if you just want "good speakers with no fuss and everything built in"... go look at the KEF LSX https://uk.kef.com/products/lsx https://uk.kef.com/products/lsx . They're not superlative compared to the others I mentioned, but they are superlative compared to a Sonos or equivalent. If you have a huge room they still may disappear and sound weak, but they'll do OK for most family rooms in most countries.
dsr_ 4y ago
Meanwhile, this paragraph from the paper: "A more effective but expensive option is to optimise the impedance match between the driver and the acoustic load. In 1940 Terman [4] patented a sound- absorbing apparatus that absorbs the backside radiation from a loudspeaker using a horn. As depicted in Figure 2, the principle is to continuously adapt the impedance from the back of the driver to the end of the cabinet in order to prevent any reflection. Despite its effectiveness, better than a simple pipe as used in the KEF Carlton, this technology suffers from several drawbacks in addition to the cost and a limited control of the wadding acoustical properties. The most obvious is the size: to work correctly, horns should be very long." Turned into the Nautaloss: https://www.diyaudio.com/community/threads/the-nautaloss-ref-monitor.247598/ https://www.diyaudio.com/community/threads/the-nautaloss-ref... which is small (because the horn is curled up), cheap (because it's made of foamcore board), and really good at absorbing high frequencies (foamcore material properties). Key paragraph from the writeup: "This speaker can be constructed from exactly 1 sheet of $1 foam core stock and the Vifa driver costs $10. These are not the most efficient drivers but at 85 dB for 2.83V input, they are not bad for near field use. The frequency response flatness, the low THD, the linear phase variations, and the near ideal impulse response make them perhaps one of the best values for a near field "monitor" from 200 Hz to 20 kHz." And of course, ideas from the 1940s are no longer covered by patents.
- xnorswap 4y ago
  The Nautaloss is no-doubt inspired by the Bowers & Wilkins Nautilus: https://shop.martinshifi.co.uk/products/b-w-nautilus https://shop.martinshifi.co.uk/products/b-w-nautilus Those however are definitely not as cheap!

33 points by Kaibeezy 4y ago

Metamarketing Emitter for Loudspeaker Sales? Fig. 6 looks a lot like I imagined Culture ships. Dense complex ridge-and-channel waveguides.

dmos62 4y ago

Getting a 404. https://web.archive.org/web/20220525085742/https://www.aes.org/tmpFiles/elib/20220525/20758.pdf https://web.archive.org/web/20220525085742/https://www.aes.o...

AlbertoGP 4y ago
Same here, an unambiguous 404. Thanks for the Archive link, I was curious about Kaibeezy’s reference to Culture ships. Now, as I write this you posted 1 hour ago, and the story submission was 3 hours ago, therefore the file would have been taken down during that two hour window. Curiously, buro9’s comment, which seems to imply that they did look at the document, was 38 minutes ago. Maybe they took a while to read it, and commented some time later? That would put the take-down time to not long before you first reported the 404, assuming buro9 took around half an hour to look at it before commenting. I doubt they got such an increase in requests that they noticed and somehow decided to take it down. Does anyone have an idea what could have happened here?
- buro9 4y ago
  The correct link is in my comment. I'd read this before, but knew immediately what it was... saw the archive link and remembered where the original was. I think their `browse.cfm` has session identifiers implicit in it (or a referrer check), and all that happen is it worked for the person who posted it but no-one else. Culture ships were all described as ellipsoid were they not? With field management controlling the outer skins.
aj7 4y ago
Can only get cover page. Is there something I don’t understand about the mechanicsof web archive?

buro9 4y ago

I knew this was going to be about or by KEF from the title. This is the link to the paper: https://www.aes.org/e-lib/browse.cfm?elib=20758 https://www.aes.org/e-lib/browse.cfm?elib=20758 These are speakers with this: https://uk.kef.com/pages/ls50-meta https://uk.kef.com/pages/ls50-meta And this is the marketing page for the same item as the paper covers: https://uk.kef.com/pages/metamaterial https://uk.kef.com/pages/metamaterial I listened to these speakers... they are good. But I didn't find them "better" than others I listened to in my room (I home auditioned quite a few speaker pairs), a bit too crisp, cold and surgical. That was likely nothing to do with the metamaterial absorption and probably more to do with the way the electronics inside worked. YMMV, listen to them to find out. In the end for me, I opted for far more traditional speakers: near field I have some PSI Audio studio monitors ( https://www.psiaudio.swiss/ https://www.psiaudio.swiss/ ), and for the larger room some Tannoy Eatons ( https://www.tannoy.com/product.html?modelCode=P0DEL https://www.tannoy.com/product.html?modelCode=P0DEL ). I do have some recent KEFs, but they're for the kitchen radio(!). I would be far more interested in this material and approach being taken out of loudspeakers and implemented in transport modes that have high background noise, or in baffles in concert halls (or even cafes!).

balfirevic 4y ago
> I have some PSI Audio studio monitors Ouch, those are expensive. Any small studio monitors (4 or 5 inch woofer) you'd recommend in $500-$600 range (per speaker)? I can't really try many out where I live, unfortunately.
- buro9 4y ago
  Audio is very personal. As a vague hand-wavey thing, humans hear 95% of the same thing (women hear more!) and it's the individual 5% difference that matters. Plus the room you place speakers in matters (lots of hard surfaces in a room that is a box makes a messy sound that bounces around, you have to shape the acoustics to avoid making good speakers sound bad and also to make good speakers sound great), and if the room is large small speakers can disappear and sound small. And of course what you listen to also matters. The PSI Audio are studio monitors... they reveal everything, they're as close to perfect as you can imagine so long as you sit 1m from them (I've been in studios, these sound like being there with the band). But studio monitors reveal all the flaws too. They're not for everyone, in fact they're not far the vast majority of people. I can't really help based on what you asked... room size, music style, how good your ears are, whether you want active (amp built in) or passive (needs an amp), what your usual music source is... these are all the big parameters. But for your budget, if you just want "good speakers with no fuss and everything built in"... go look at the KEF LSX https://uk.kef.com/products/lsx https://uk.kef.com/products/lsx . They're not superlative compared to the others I mentioned, but they are superlative compared to a Sonos or equivalent. If you have a huge room they still may disappear and sound weak, but they'll do OK for most family rooms in most countries.

dsr_ 4y ago

Meanwhile, this paragraph from the paper: "A more effective but expensive option is to optimise the impedance match between the driver and the acoustic load. In 1940 Terman [4] patented a sound- absorbing apparatus that absorbs the backside radiation from a loudspeaker using a horn. As depicted in Figure 2, the principle is to continuously adapt the impedance from the back of the driver to the end of the cabinet in order to prevent any reflection. Despite its effectiveness, better than a simple pipe as used in the KEF Carlton, this technology suffers from several drawbacks in addition to the cost and a limited control of the wadding acoustical properties. The most obvious is the size: to work correctly, horns should be very long." Turned into the Nautaloss: https://www.diyaudio.com/community/threads/the-nautaloss-ref-monitor.247598/ https://www.diyaudio.com/community/threads/the-nautaloss-ref... which is small (because the horn is curled up), cheap (because it's made of foamcore board), and really good at absorbing high frequencies (foamcore material properties). Key paragraph from the writeup: "This speaker can be constructed from exactly 1 sheet of $1 foam core stock and the Vifa driver costs $10. These are not the most efficient drivers but at 85 dB for 2.83V input, they are not bad for near field use. The frequency response flatness, the low THD, the linear phase variations, and the near ideal impulse response make them perhaps one of the best values for a near field "monitor" from 200 Hz to 20 kHz." And of course, ideas from the 1940s are no longer covered by patents.

xnorswap 4y ago
The Nautaloss is no-doubt inspired by the Bowers & Wilkins Nautilus: https://shop.martinshifi.co.uk/products/b-w-nautilus https://shop.martinshifi.co.uk/products/b-w-nautilus Those however are definitely not as cheap!