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Evidence-based Speaker Designs

Ron Texas

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Some actives will have inputs labeled -10 dbv for consumer and +4 dbu for pro. The consumer setting required about 3.1 volts for Max out. The pro setting required about 12 volts for Max out. Of course there are exceptions. Something with 3 or 4 volts out is unlikely to be a problem.

If I go that route, I would probably pick up an audio interface if the inputs are analog, or a USB to AES/EBU converter.

Truth be told, I am liking things in my present setup a lot more with the floor resonance problem solved. Right now it seems intuitive, but it took me a few months to figure it out. I like the LS50's for their imaging and tonality. My guess is they don't sound right to some younger listeners because KEF intentionally made them a bit brighter for an older audience. Just my idea.
 

graz_lag

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@RayDunzl, I don't know. My thinking right now is either keep the D30/LS50/Dynamo 1000W/XLS 1502 combo or look for active speakers, either with or without a built in DAC. The problem is most of them are not decor friendly.

Have you ever considered the Dynaudio AIR series ?
Outstanding product, IMHO.
 

svart-hvitt

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Yes, last year or the year before ... but that doesn't jeopardize the product technology.

Studios, which were the target market for the AIR series, are the best source for second hand units at very reasonable prices.

Yes, nice 2nd hand units are the best choice; sustainability and unbeatable price/performance.

:)
 

Cosmik

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In the world of speakers I get the impression that there has been a lot of solid development invested in BT speakers and sound bars.
I am sceptical. I actually went to a manufacturers' symposium on such technology, and it is all about synthesising harmonics to create an impression of bass, limiting deep bass at high volume etc. In one sense, fiendishly clever if you consider what is coming out of a tiny speaker, but really all in the service of making a box a bit smaller than it might otherwise be. Surely you and I aren't interested in making boxes smaller than they need to be? I am often struck by the irony of audiophiles spending £50,000 on their system to make it compatible with their tiny room when they could spend the money on a new wing to their house.
 

Ron Texas

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I am sceptical. I am often struck by the irony of audiophiles spending £50,000 on their system to make it compatible with their tiny room when they could spend the money on a new wing to their house.

I don't have any room left to build. Wait, I could throw my wife out and take over the living room.
 

Blumlein 88

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I am sceptical. I actually went to a manufacturers' symposium on such technology, and it is all about synthesising harmonics to create an impression of bass, limiting deep bass at high volume etc. In one sense, fiendishly clever if you consider what is coming out of a tiny speaker, but really all in the service of making a box a bit smaller than it might otherwise be. Surely you and I aren't interested in making boxes smaller than they need to be? I am often struck by the irony of audiophiles spending £50,000 on their system to make it compatible with their tiny room when they could spend the money on a new wing to their house.

People in smaller abodes just need more creativity. Use the wasted space in the attic, crawlspace, basement or closet.

I had hoped these rotary woofers would become more common.
https://www.cnet.com/news/worlds-most-amazing-subwoofer-has-no-woofer/

But even conventional woofers can be fit in somewhere.
https://www.audioholics.com/diy-audio/hidden-in-floor-in-ceiling-subwoofer-installation

https://www.avsforum.com/forum/155-...-quad-18-floor-infinite-baffle-subwoofer.html
These feed into a vent in the floor.
1549500845811.png


1549500895259.png

1549500924399.png

https://ibsubwoofer.blogspot.com/2007/04/manifold-box.html
 
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Ilkless

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Is prioritizing constant directivity inherently more science based than prioritizing dynamic range, minimizing the audible effects of cabinet resonance, or even creating a sense of envelopment from a 2.1 system?

As I replied earlier, the starting point with directivity is a definable accuracy per Geddes - the uniformity of spread of acoustic radiation. Specifically, cabinet resonance can be measured for its contribution to this radiated sound, and compared to how much is radiated by the transducers. Nonetheless it is clear that making minimising secondary radiation the primary aim is missing the forest for the trees, akin to Thiel's dogma of sloped baffles with passive first-order crossovers.

Edit: Also, I totally agree with Prof Toole that resonances come first. It is just that I consider it such a low bar to clear that it is inexcusable for a manufacturer to not consciously seek to minimise them. And with how inexcusable it is, it is irrelevant for the purposes of this thread, which focuses on perhaps the second-order question of directivity.

Edit2: the controversy over this thread is surprising considering the relatively muted response to the "state-of-the-art" speakers thread, which would also entail some degree of judgment as to the objective performance of speakers for a given set of paramete
 
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Ron Texas

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People in smaller abodes just need more creativity. Use the wasted space in the attic, crawlspace, basement or closet.

I had hoped these rotary woofers would become more common.
https://www.cnet.com/news/worlds-most-amazing-subwoofer-has-no-woofer/

But even conventional woofers can be fit in somewhere.
https://www.audioholics.com/diy-audio/hidden-in-floor-in-ceiling-subwoofer-installation

https://www.avsforum.com/forum/155-...-quad-18-floor-infinite-baffle-subwoofer.html
These feed into a vent in the floor.
View attachment 21477

View attachment 21478
View attachment 21479
https://ibsubwoofer.blogspot.com/2007/04/manifold-box.html

Can I watch "2012" at your house. It has to be some serious shaking stuff. How about the choppers in "Battlefield LA"
 

JJB70

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I am sceptical. I actually went to a manufacturers' symposium on such technology, and it is all about synthesising harmonics to create an impression of bass, limiting deep bass at high volume etc. In one sense, fiendishly clever if you consider what is coming out of a tiny speaker, but really all in the service of making a box a bit smaller than it might otherwise be. Surely you and I aren't interested in making boxes smaller than they need to be? I am often struck by the irony of audiophiles spending £50,000 on their system to make it compatible with their tiny room when they could spend the money on a new wing to their house.

But I think that is sort of the point, whether or not you or I like the results or are in the market for that type of product doesn't alter the fact that there is a lot of solid scientific/engineering research and development effort being invested in these speakers. I think they're indicative of how the market has developed, sound has been commoditised and most people out there really aren't interested in HiFi or audio gear, they just want something that is simple and inconspicuous and which can fill their room with sound of an acceptable quality. Many years ago most audio enthusiasts dismissed the work being done by Bose to develop high price lifestyle systems and speakers, but I think Bose were way ahead of the curve and read the market better than anyone, and whatever I think of their product I don't think anybody can deny that Bose have a rich pedigree of research and development. For a long time I found most of those type speakers were one trick ponies, there was an initial "look at me, how can something this small make so much sound!!" type of reaction followed by a sense that although the sound was remarkably "big" for such small speakers it wasn't very good. Now, I listen to more and more of these speakers and find that the sound is actually very acceptable. A friend just bought a Samsung speaker, it is quite bulky as these things go and wasn't cheap (apparently it was £600), you or I would probably say he could have bought some respectable stereo speakers (either active, or passive with a low cost amp) for the same price or not much more and which would sound better but that misses the point. He wanted something in one box he just had to plug in and drop onto the unit it sits on and which sounded good. And it does sound good, very good in fact, although I'm not sure it's reached a point where such a speaker would be my first choice I would also say I can listen to it and enjoy music. And then there are sound bars. The steadily improving performance of BT speakers and sound bars and the technologies on display demonstrate the research and develop effort being invested in them I think.
 

MattHooper

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Hello again. I've been otherwise engaged for a while and am catching up. You are right that the strongest evidence linked to perceived sound quality in a room is a comprehensive set of anechoic data. Room curves are only loosely connected, except at low frequencies where they are the only reliable data. When we see a family of on- and off-axis anechoic curves, all smooth and indicating either constant DI or gradually rising DI we have learned (a) that there are no audible resonances and (b) that the spectral balance of direct and reflected sounds will have something in common. Which is more important? I vote for the absence of resonances, because timbral colorations of that kind are easily heard and corrupt all program material independent of the listening space. Neutral loudspeakers tend to "disappear" behind the double-blind screen, allowing the spatial cues in recordings to be heard.

The matching of direct and reflected spectral balances is less well defined. In Figure 7.12 in my current book describes an elaborate test done around 1985. I show that the least preferred loudspeaker had arguably the most constant DI, but was more directional than the higher rated speakers with quite uneven off axis radiation, but more of it. Listeners seemed to have voted for more "space" and seemed to be able to rationalize the low-Q directional variations. BTW the spatial perceptions cannot be "envelopment" in the classic sense because that is correlated with much delayed (e.g. 100 ms) sounds, as in concert halls. This is why multichannel reproduction has huge advantages. What is it then, that causes the preference for some reflected sounds? My personal theory is that it has to do with the fundamental limitation of two-channel stereo, in which some of the sound almost inevitably emerges from the L or R loudspeakers - hard panned by console controls or by mic techniques. When this happens close miked solo instruments or groups of orchestra instruments emerge from a point in space. I have found this to be highly annoying in some recordings as it is plainly unrealistic. Spraying the sound around adjacent walls softens the mono L&R images. It also softens the amplitude panned images between the loudspeakers which some people disparage and others find appealing. The musical genre is likely a factor. But the basic issue is that conventional stereo cannot deliver the goods and we look for ways to improve it.

Is constant directivity, including omnidirectIonality, better than the slightly increasing DI of conventional forward-firing cones and domes? Having heard both over many years I have no preference. If there are no audible resonances the difference devolves to the localized sense of space and delocalization I just described. Neither is more "correct" in stereo reproduction. In multichannel systems it simply does not matter - with more real sound sources direct sounds dominate. Forward firing designs occupy less room volume and are likely to be preferred.

My current preference for multichannel upmixing is based on its superior performance and its adjustability for different programs. Such a system also permits playback of multichannel music recordings, music videos (some of which are excellent) and movies. If your circumstances permit it, I highly recommend it.

Here is a link to a description of my present system:
https://www.dropbox.com/s/gg5wnct6010gvuq/3-Part Toole Home Theater 2018.pdf?dl=0

What a wonderfully comprehensive reply. A pleasure to read. Thank you Dr. Toole!

And boy your theater room must sound spectacular. Loved reading all the thought put in to it. (I agonized for years constructing my own theater/music listening room).
 
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GGroch

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JJB70, you make some valid and interesting points concerning Bose approach.

I sold audio during the late 80's and 90's and during that period Bose's Acoustimass 3 piece sub/sat systems for a good while held a ridiculously huge percentage of the over $500 home speaker market share. I do not remember the figure now, but if memory serves it was over 50%.

You mention some of the reasons for this popularity, the desire for simple inconspicuous sound that fills a room, which became increasingly important as people replaced huge rear projection TVs with flat panels. But the speaker's directivity, the use of reflected sound, was also a major factor. There is no doubt that Bose's unique spread patterns were the result of evidence-based research consistent with acoustical physics and psychoacoustics. Back then, Bose advertised having invested over $100 million dollars in research, which is no doubt more than the entire list of evidence based companies at the start of this thread.

To quote Dr. Toole (probably out of context ;) "the basic issue is that conventional stereo cannot deliver the goods and we look for ways to improve it." Instead of prioritizing creation of a realistic soundstage at a single central sweet spot. Bose's direct/reflecting & "stereo everywhere" technologies aimed at providing some sense of space for multiple listeners positioned nearly anywhere in the room.

As an audiophile I did not buy into this concept, as a commissioned salesperson I learned to become more agnostic. Evidence based selling convinced me that my own audiophile priorities did not necessarily reflect the needs of a lot of potential speaker buyers.

Perhaps they were ignorant, or perhaps their rooms and lifestyles were not as focused on the solitary audiophile experience as I was.
 

Ron Texas

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I strongly suggest you check it before with Bogeyman that sleeps under it so he wouldn't be upset. :D

Uh Oh, I better cut the legs off the bed.:rolleyes:
 
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