There is only three settings as I recall and one - Omni - was not useable IMO. So you have narrow or wider. I would say that somewhere in between those two, as a fixed pattern, would almost always work fine - lots simpler and cheaper.
My experience is that there is not one polar response that is "right" for all rooms as its the speaker+ room that needs to be "right". I agree with this goal (accuracy ie 'right"), but the speaker and room can't be separated IME.
DDF - I don't quite agree, I think that narrow is best, until it gets impractical and ineffective, i.e. < 60 degrees wide would not seem to be worthwhile. About 90 degrees works well because it will avoid reflection from the near side wall if toed-in. >90 and placement gets difficult without creating very early reflections. Of course if you want VERs then wider is better - that may be a matter of choice dictated by the musical source preference.
Agreed.
For a while there, I though that there were some advantages to wide directivity. For instance, it can sound more 'spacious.' And narrow waveguides seem to suffer from frequency response problems more.
But after listening to relatively narrow waveguides, I've noticed that they definitely yield a 'giant headphone' effect that can be really pleasant. An ability to hear things in the recording which are otherwise smeared by reflections.
TBH, it would be great to have a couple of rooms, each with a different style of loudspeaker, but if I had to pick one it would be somewhere around 75 degrees, give or take 20%
One thing that troubles me is that they compared it to a BeoLab 5, and it trounces the '5' in the polar response.
This is a bit suspect, as the polars which were originally published, nearly a decade ago, looked a lot better.
So either the old polars were too good to be true, or the new polars are too bad to be true.
I've messed around a lot with SAW lenses and they work nicely. It's hard to fathom why the Beolab 5 polars would be so poor.
Here's the published polars of the Beolab 5, from nearly ten years ago
Here's the published polars of the Beolab 5, from last month
Here's the published polars of the Beolab 90, from last month
See the discrepancy?
Data courtesy of Beolab (http://www.tonmeister.ca/wordpress/) and Moulton Labs (http://www.moultonlabs.com/more/new_loudspeaker_design/P1/)
My employer is a B&O reseller and the opinions expressed here are not intended to represent them, and are purely my own.
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I think it's a matter of preference. While I see this value of narrow directivity, I personally don't subscribe to the "great detail safari hunt" as Corey Greenberg amusingly termed it and find it too dry if overdone. But certainly the greater the DI and the deader the room (or bigger), the less speaker/room interaction matters.
Patrick, did you notice that old measurement starts at 1000Hz, new at 100Hz. If I scale them equally, they are pretty much the same.
As in general about directivity, we have many great home speakers with wide &smooth directivity eg. Magico and Avalons. Many suffer from ragged directivity like Wilson, Marten and many many esoteric high-end speakers. A large speaker is usually in a large and "well tempered" room, sharp directivity is not needed to minimize first reflections but wide directivity emphasizes late ones to imitate hall sound and gives wide listening area. Dipoles can do the same.
So, I don't believe that there is just one really good directivity pattern. Geddes gives good reasons for that, but still... It is good to have options , just like some people prefer Corvettes over Porsches! Or Hyundai vs. Toyota.
As in general about directivity, we have many great home speakers with wide &smooth directivity eg. Magico and Avalons. Many suffer from ragged directivity like Wilson, Marten and many many esoteric high-end speakers. A large speaker is usually in a large and "well tempered" room, sharp directivity is not needed to minimize first reflections but wide directivity emphasizes late ones to imitate hall sound and gives wide listening area. Dipoles can do the same.
So, I don't believe that there is just one really good directivity pattern. Geddes gives good reasons for that, but still... It is good to have options , just like some people prefer Corvettes over Porsches! Or Hyundai vs. Toyota.
I loved his reviews too. Many years ago after his buffered passive, he moved on from audio reporting. I think he's the Today show's tech editor. His toned down but still a touch of gonzo approach was just what audio reporting needed. I think he's become involved somehow with Stereophile again, but I don't read the audio press anymore, not sure
DDF - I don't agree with side wall damping at the first reflection because it is the lateral reflections that create the most "spaciousness" and eliminating them is detrimental to this aspect. The front wall definitely, but that is the only wall that I would dampen at HFs (excluding floor bounce and ceiling which need other solutions.)
I diffuse that reflection, not absorb it, so that it does not arrive at the listener, but does not just go away either.
While that's find for listening, it's not an absolute accurate method of treatment. Neither is having reflective sidewalls.
Firstly, diffusing a surface where the distance is short implies only dealing with higher frequencies. Diffusion lower in frequency would require not only a very deep diffuser but also ideally 3 wavelenght distance to the diffused energy.
Secondly, when using diffusers at early arriving reflection points one is in a way coloring the recorded signal because the sound is spread out in space and time (if it perfoms temporal diffusion).
Using thick absorbents for early reflections is a more accurate way of treatment. Even better is splayed walls/ceiling.
Leaving sidewalls reflective will also have a detrimental effect on accuracy, even in a wide room.
Again, this may be find for casual listening. However, in a control room where critical listening is important this would not be the best type of treatment.
Omholt - I don't agree with your assessment of diffusion or reflection. And I know how diffusers work and how to design them. Absorbers don't work at LFs either - nothing but wall motion can affect LFs in a small room.
Not if they are not illuminated by the source.
All room reflections do that - its called reverberation.
Not if they are not illuminated by the source.
All room reflections do that - its called reverberation.
A thick and big absorber will work well down to the schroeder frequency.
A diffuser won't unless it's encredible deep. Plus you need the mentioned 3 wavelength distance to the diffused energy. If not, you will hear discrete reflections. Thus, there isn't enough distance when treating the ceiling in a living room. So it becomes a rather bandlimited treatment and you've also made the recorded signal sound more spacious than what it is because of the arrival time of the energy.
There's no doubt that thick absorbents used to treat early reflections is a more spectral neutral treatment. This give the highest resolution, the best clarity, intelligibility, tonality and localisation. Diffusion will make the sound more spacious but the accuracy and imaging will suffer compared to absorption.
For late arrival reflections, it's different.
A diffuser won't unless it's encredible deep. Plus you need the mentioned 3 wavelength distance to the diffused energy. If not, you will hear discrete reflections. Thus, there isn't enough distance when treating the ceiling in a living room. So it becomes a rather bandlimited treatment and you've also made the recorded signal sound more spacious than what it is because of the arrival time of the energy.
There's no doubt that thick absorbents used to treat early reflections is a more spectral neutral treatment. This give the highest resolution, the best clarity, intelligibility, tonality and localisation. Diffusion will make the sound more spacious but the accuracy and imaging will suffer compared to absorption.
For late arrival reflections, it's different.
Absorbers have the same depth limitations for LFs that diffusers do. They are both affected by the depth and the LF limitations equally.
I either don't understand your point or I don't agree with it. Diffusion will make the sound more spacious, that's why I do it, but I don't agree that it will do so at the sake of imaging. I don't get that point. There isn't much of an "imaging" effect from the ceiling reflection because it is equal at the two ears. It does color the sound however.
I should say that my ceiling treatment is probably both diffusion and some absorption because of its design. It eliminates the first ceiling reflection that much I know from the measurements. How much is diffuse and how much absorbed I really couldn't say.
In small rooms I think that the absorption should be kept to a minimum because absorption is so effective in a small room. It is easy to get the room too dead.
I either don't understand your point or I don't agree with it. Diffusion will make the sound more spacious, that's why I do it, but I don't agree that it will do so at the sake of imaging. I don't get that point. There isn't much of an "imaging" effect from the ceiling reflection because it is equal at the two ears. It does color the sound however.
I should say that my ceiling treatment is probably both diffusion and some absorption because of its design. It eliminates the first ceiling reflection that much I know from the measurements. How much is diffuse and how much absorbed I really couldn't say.
In small rooms I think that the absorption should be kept to a minimum because absorption is so effective in a small room. It is easy to get the room too dead.
Not equally, though it depends somewhat on type of diffuser. An absorber with 6" depth will absorb very well down to 200 Hz (with sufficient height and width), random incidence.
That's something you will not achieve with a diffuser with the same depth. You will not even be close. Not to mention that a diffuser without fractals will not diffuse above 4-5KHz.
And again, even if you use a diffuser that works that low in frequency, you don't have the needed distance for the frequencies to be diffused.
You can't have both 100% spaciousness and 100% accuracy when treating early reflections. Either one will suffer. Attenuating the early specular reflection with broadband absorption gives the most accurate presentation. Though we are more senstive to lateral reflections, it's also the case with vertical reflections. Both have an effect on an accurate presentation.
Every diffuser absorbs the sound as well. A diffusor with typical 5-7" depth will be a quite frequency limited treatment. So it with not eliminate the reflections from the ceiling as you say. This would easily be seen in a bandlimited ETC.
Sure, that's why absorption should be placed surgically at reflection points. And it's vital to treat early reflections broadband and also treat the LF with bass trapping.
A common mistake is treating specular reflections with too thin absorption (typical 2-4" absorbents). When treating broadband, we can tolerate more without making the room dead.
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Making "the recorded signal sound more spacious than what it is" is somewhat necessary to achieve subjective realism for most people I'd think. If you've ever set up a stereo system outdoors or in something approaching anechoic conditions you probably know that listening that way sounds quite un-natural and unsatisfying (at least it does for me and others I've discussed this with).
This relates somewhat to Earl's thread about limits of "Hi-fi intent". It's one of the situations where absolute accuracy is more or less by necessity just tossed out the window, as there is none of that property (spaciousness that is due to sound coming from many directions around the listener) in existence to reproduce with an objective accuracy. The room has to provide that part of it, at least with stereo source material (which is most of what we have to work with in current recorded music libraries).
This relates somewhat to Earl's thread about limits of "Hi-fi intent". It's one of the situations where absolute accuracy is more or less by necessity just tossed out the window, as there is none of that property (spaciousness that is due to sound coming from many directions around the listener) in existence to reproduce with an objective accuracy. The room has to provide that part of it, at least with stereo source material (which is most of what we have to work with in current recorded music libraries).
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