Hot-spotting with atmos: A solution?

[Bjarte T.]

Hi, I am new here. I regard Audioholics as a solid source when it comes to information about audio and hi-fi, and it also seems to attract knowledgeable forum participants. I am therefore hoping to get some more clarity on my topic here, which is atmos speakers and «hot-spotting».

I'm considering buying a 5.1.2 / 5.2.2 surround speaker setup, and I'm looking towards Audiovectors QR series.

I've heard advices of avoiding the use of atmos speakers all-together in cases where the ceiling height is much less than 10 feet / 3 meters (including Gene DellaSala, and also Dolby, if I remember correctly) because it results in focused, direct surround sounds, which can be a distraction («hot-spotting», as I understand it). My ceiling height is 7.9 feet (240 cm).

I am thinking of Audiovector QR Wall as atmos speakers. A crucial reason for why I am considering these, besides having appropriate dimensions (depth of 3.7 inches (9.5 cm)), is that this speaker has a so called diffuse mode. This is made possible with the use of an extra set of tweeters. The diffuse mode can be switched on and off.

There is not a lot of information about this. Audiovector has not done it’s marketing job in this regard. My guess, from my understanding of diffused field of sound, is that this is made with surround in mind, in cases where the space is sparse. I would therefore think this in theory could accommodate the problem with low ceiling heights (or normal ceiling heights, as we call it, here in Norway) when used as atmos speakers.

Wikipedia defines diffuse sound field as a sound field where soundwaves are traveling in all directions with equal probability. «In a diffuse field the sound at each of a listeners' ears is so completely different that it is impossible for the brain to work out where the sound has come from. A diffuse source located in front of the listener will be hard to localize and can be used to carry the surround signals.»

Can anyone give me some general remarks about what you think about this solution? I know Gene DellaSala have touched upon this topic in his article «Dipole vs Bipole vs Monopole: Which Surround Speaker is Best?», but unfortunately I didn’t get much wiser in regards to hot-spotting and atmos. I have heard, from first hand experience with this speaker and it's diffuse mode, from a YouTube channel representing a foreign Hi-fi magazine, is that it is making the sound feel like it is much further back then it is. This approach, of using a diffuse mode, isn't something I have seen in other speakers, though.

So, is there a good chance this could work out? Does anyone here know about Audiovector's diffuse mode solution from earlier times (I've been told that Audiovector has used this before), or has anyone here seen or heard a solution like this in other speakers, or just having thoughts about this in general?

I would be very happy for feedback.

Picture of the speaker below:

More information: http://audiovector.com/qr-wall.html

 

[Pogre]

Well first off, if English isn't your first language, you type very well.

Just so I'm clear, you want to try these speakers in an atmos setup because your ceiling height is shorter than what's recommended? There are other in ceiling/on wall speakers that use 2 tweeters with diffusion in mind. Atmos is not one of my strengths so I'll stop there. I'm sure someone here will help you in a lot more detail.

Welcome to the forums!

 

[panteragstk]

I'm wondering what mounting location you have planned for those speakers. To work in an Atmos setup they'd have to be VERY close to or on the ceiling. The point you made about ceiling speakers is true, but more than one manufacturer have maid diffuse ceiling speakers to compensate for this. In the ceiling really is the best place for Atmos speakers. The ones that bounce the sound off the ceiling are also supposedly pretty good, but I'm guessing that depends on brand.

 

[Bjarte T.]

Pogre: Thank you for your kind words Yep, that’s correct. I am hoping this could compensate for short speaker distances. (I would use normal sized bookshelf speakers as front speakers, from the same series.)

Panteragstk: My ceiling is made of concrete, so I don't have the ability to install in-ceiling speakers. I'm a bit skeptical of atmos enabled speakers, where sound is bounced of the ceiling.

I would like to know the names of other speakers which is similar in regard to diffusion, as it may be much easier to find any information and reviews of those solutions then it is of these QR-speakers, as they are newly released. It would be interesting to see if this has been successfully implemented by other brands.

 

[panteragstk]

You could always do on-ceiling speakers instead of in-ceiling. Flush mounting the speakers should work well.

The diffuse speakers I know of are in-ceiling. I don't know of any other brands that make them. Sorry.

 

[BlwnAway]

A couple of things, yes a diffuse speaker is recommended with in-ceiling or on-ceiling speakers, so with that in mind, since those speakers utilise a ribbon tweeter, which in some cases will have a narrower vertical dispersion, you will probably be better off mounting them so that the wider dispersion area (horizontal) is actually aimed front-to rear, instead of side-to side, if you can mount them above you, on-ceiling.
Also, because of your ceiling, if you can't mount them as on-ceiling, you may want to consider mounting them as Heights, as close to the ceiling as you can, but on the walls within what would be the proper angles for TM placement. While middle heights not being ideal, it should still give you a better effect over a reflective option.

 

[yepimonfire]

You could always do on-ceiling speakers instead of in-ceiling. Flush mounting the speakers should work well.

The diffuse speakers I know of are in-ceiling. I don't know of any other brands that make them. Sorry.

This is what I do. In all honesty, real bookshelves will outperform ceiling speakers in a lot of ways. I am not impressed by atmos modules, the only one I've heard that actually sort of worked was the Klipsch 140sa, likely due to an intentional narrow dispersion pattern using a horn, but it was still lousy in comparison to real overhead speakers.

My current setup involves a 5.1.2 configuration with an 8' ceiling using two bookshelf speakers mounted directly in line with my front speakers (approximately 7.5' apart) slightly in front of the mlp at about 80°. I have them aimed directly at the mlp. The room is 20'x12' and the mlp is 9' from the front. The overhead speakers are 3.5' above ear level, and 5 1/2' from the center seat.

Hotspotting is only an issue if one is sitting in front of or significantly behind the mlp.

Avoiding Hotspotting whilst achieving the proper imaging with atmos is tricky. On one hand, atmos is designed for direct sound, the old standard of using bipoles or mounting speakers above ear level is not a part of atmos, all speakers should be pointed directly at the listener. 5.1.4 would certainly help, especially if you've got multiple seats. The other thing that would help is making sure your fronts are exactly 30° (equidistant to the distance from the front) and the atmos speakers are the same distance apart. Choosing speakers that can be point directly down would be a good choice as well. The speakers I originally had mounted to my ceiling were a pair of Polk Audio OWM3's, the sound from them was very broad and enveloping, and I had a hard time localizing them. The only reason I replaced them with much easier to localize Klipsch bookshelves is because of a large timbre difference between those and the rest of my Klipsch speakers, I like using Dolby surround for music listening, and the mismatch was distractingly obvious during this. For movies it wasn't as noticeable.

You say you have a concrete ceiling? Is the entire room concrete? If so, I would strongly suggest room treatment, otherwise the amount of reflections will make it hard to localize anything, completely smearing the imaging.

Sent from my 5065N using Tapatalk

 

[Bjarte T.]

A couple of things, yes a diffuse speaker is recommended with in-ceiling or on-ceiling speakers, so with that in mind, since those speakers utilise a ribbon tweeter, which in some cases will have a narrower vertical dispersion, you will probably be better off mounting them so that the wider dispersion area (horizontal) is actually aimed front-to rear, instead of side-to side, if you can mount them above you, on-ceiling.

Yes, if mounted sideways the sweat spot would be quite narrow due to narrow vertical dispersion. It has a extra sets of tweeters, though, which can be seen in the picture, which can be switched on (they account for the "diffuse mode", which I would use for atmos).

I can mount them on-ceiling, that shouldn't be too much of a problem. In-ceiling is out of the question, though.

 

[Bjarte T.]

Avoiding Hotspotting whilst achieving the proper imaging with atmos is tricky. On one hand, atmos is designed for direct sound, the old standard of using bipoles or mounting speakers above ear level is not a part of atmos, all speakers should be pointed directly at the listener.

Yes, exactly right. Finding a good balance between diffusion and accuracy, being able to place the sounds in it's rightfull place in a broad soundscape, seems to be the key.

So the question is wether a diffuse speaker, like QR Wall, would be able to strike a good balance for a given distance (1.5 meters in my case). Also, how this would interfere with rear speakers having the same characteristics (having the same diffuse-mode on).

(The distance from rear speakers to my listening position would be about 1.1 meters, and the distance between each of rear speakers to it's closest atmos speakers would be about the same distance as my listening position and atmos speakers (1.5 meters)...)

In regards to my room acoustic, only the ceiling is concrete. I do also have a carpet in front of the speakers, taking care of some of the early reflections from the floor.

 

[yepimonfire]

Yes, exactly right. Finding a good balance between diffusion and accuracy, being able to place the sounds in it's rightfull place in a broad soundscape, seems to be the key.

So the question is wether a diffuse speaker, like QR Wall, would be able to strike a good balance for a given distance (1.5 meters in my case). Also, how this would interfere with rear speakers having the same characteristics (having the same diffuse-mode on).

(The distance from rear speakers to my listening position would be about 1.1 meters, and the distance between each of rear speakers to it's closest atmos speakers would be about the same distance as my listening position and atmos speakers (1.5 meters)...)

In regards to my room acoustic, only the ceiling is concrete. I do also have a carpet in front of the speakers, taking care of some of the early reflections from the floor.

I would not use diffuse speakers at all, rather, I would focus more on placement of speakers and the listening position. Use wide dispersion speakers for the heights and aim them straight down. Dolby requires a dispersion from 100hz - 10khz at 80° in order to aim the speakers straight down. A pair of Klipsch R-14m or 15m has an even controlled dispersion pattern of 90° from 1.8khz to 14khz and would be a good speaker to aim straight down. Do note the old reference II series speakers are very beamy and will not work for down firing speakers, only the premier and new reference series.

Sent from my 5065N using Tapatalk

 

[DigitalDawn]

We install these in the ceiling in a bipole configuration for Atmos. The ceiling height should be less than 9 feet (which yours is).

http://www.triadspeakers.com/products/home-cinema/iw-bronze4-surround/

 

[Bjarte T.]

I would not use diffuse speakers at all, rather, I would focus more on placement of speakers and the listening position.

I would like to hear more of your thoughts of this. Why wouldn’t you use diffuse speakers as rear speakers?

Although I can think of some reasons myself, even though I haven’t heard it in practice, I could imagen it doing a good job if it’s executed well. I do have a 5.1 setup already, where my rear speaker is placed above my ears (the tweeter is about half a meter above listening level), and I can imagen diffuse speakers could do much of the same job as to avoiding hotspotting while having more flexible speaker placement. If it more or less overcomes the need of speaker elevation, for example, it could also render a more lively listening experience, whereas the tweeter, maybe, otherwise is more recessed then it needs to. Also, it should also be able to portray a more 3D-like/lifelike sound field. Dolbys recommendations is also to keep the channels at ear levels.

Isn’t there also different degrees of diffusion, or is it, per definition, on or off?

 

[yepimonfire]

I would like to hear more of your thoughts of this. Why wouldn’t you use diffuse speakers as rear speakers?

Although I can think of some reasons myself, even though I haven’t heard it in practice, I could imagen it doing a good job if it’s executed well. I do have a 5.1 setup already, where my rear speaker is placed above my ears (the tweeter is about half a meter above listening level), and I can imagen diffuse speakers could do much of the same job as to avoiding hotspotting while having more flexible speaker placement. If it more or less overcomes the need of speaker elevation, for example, it could also render a more lively listening experience, whereas the tweeter, maybe, otherwise is more recessed then it needs to. Also, it should also be able to portray a more 3D-like/lifelike sound field. Dolbys recommendations is also to keep the channels at ear levels.

Isn’t there also different degrees of diffusion, or is it, per definition, on or off?

I'm not sure there are degrees of diffusion, I guess we should define what we mean by diffuse. To me, it means a non directional sound that is spread out across the entire soundstage, which isn't what you want with Atmos. Options available for surround speakers are monopole, dipole, and bipole. Dipole is extremely diffuse, since the drivers are wired out of phase, no direct sound is heard from the speaker, only the reflections off the walls, bipole speakers are two sets of speakers faced 45° away from eachother, this isn't really diffuse, but it does help spread the sound out, how it does this is dependent on the design of the speaker. Horn loaded bipoles, such as many of the Klipsch wdst designs, utilize the controlled directivity of horns to expand the coverage area from 90° to 180°, which can be useful for ensuring each seat is gets equal coverage with many seats being off axis. Monopoles are self explanatory, one speaker, spraying sound in one direction. Coverage depends on the speakers design.

Sent from my 5065N using Tapatalk