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What is Dolby Atmos For Home Theater?

by August 09, 2014
A commercial Dolby Atmos setup; image sourced from Dolby.

A commercial Dolby Atmos setup; image sourced from Dolby.

Two years ago, Dolby Atmos hit the commercial theater scene with the promise of a more enveloping, and consequently more lifelike sound. The most noticeable aspect of the format was the addition of more speakers, with up to 64 channels of audio supported, including ceiling mounted speakers for overhead effects. However, the extra channels are just the beginning: as we noted in Dolby Atmos for Home Cinema, Dolby Atmos utilizes three distinct elements:

  • Bed Audio: these are channel-based stems, in 5.1 or 7.1, effectively identical to former surround-formats. The individual channels are static inside the bed.
  • Object Audio: these are mono- or stereo channels with dedicated surround panning. These channels are not in a bed, but remain individual.
  • Metadata: Surround panner metadata for Object audio and additional metadata

“Objects” can be surround panned in space on all three axes (front/rear, left/right, up/down), as well as given a size. The Metadata defines where the objects are positioned and how big they are in time. In a normal surround environment, these surround pans are transformed to output levels in the classic 7.1 mix channels. Conversely, objects are “rendered” by the Atmos engine; up to 128 different elements (9.1 bed channels plus 118 objects) can be rendered to the actual number of speakers the system has available, up to a maximum of 64 individual speaker feeds in a commercial cinema.

Atmos Object Audio

Illustration of object audio in Dolby Atmos.

The end result of all this is a more involving and pinpoint accurate experience than conventional 5.1 or 7.1 could ever offer. Instead of effects simply appearing behind or beside you, Atmos delivers a three dimensional reproduction of effects such as an airplane flying overhead, the utter sonic immersion of being in a jungle, or something as simple as the rain falling.


What is Dolby Atmos for Home Theater?

Bringing It Home

Atmos will take the form of extensions within the current Dolby TrueHD and Dolby Digital Plus codecs.

If you’ve been following the flurry of manufacturer announcements lately, Atmos isn’t just for commercial theaters anymore. D&M announced new A/V receivers from both Denon and Marantz supporting the format, as have Yamaha, Onkyo/Integra, and Pioneer. At the same time, Pioneer has launched a new line of “Atmos-enabled” speakers with other manufacturers sure to follow suit. All of this raises an important question: what exactly do you need to enjoy the benefits of Dolby Atmos at home?

Atmos

Dolby Atmos: what the numbers mean.

Before answering that question, it’s important to understand how Atmos will be delivered in the home. Atmos content will not require a new codec. Instead, it will take the form of extensions within the current Dolby TrueHD and Dolby Digital Plus codecs. As such, while you will need a new A/V receiver to take advantage of these extensions (older models will simply play the base TrueHD/Digital Plus content), Blu-ray players that fully conform to the Blu-ray specification will support Atmos without requiring a firmware update. Moreover, despite what cable salesmen might state in the future, you don’t need new HDMI cables either.     

your current Blu-ray player supports Dolby Atmos with no firmware upgrade required.

What about the speakers? Atmos in the home supports up to 24 speakers on the floor and 10 overhead speakers (34 speakers total), and Dolby has noted that one partner is already planning on releasing a 32 channel A/V receiver to take advantage of this expandability. However, you don’t need a room full of speakers to benefit from Atmos. Currently, the options are largely limited to 11.1 channels of audio, with a few different configurations options to consider.

Dolby Atmos Speaker Configuration Options for Home Theater

  • 5.1.2: A standard 5.1 setup with a pair of “middle” in-ceiling/ceiling-mounted speakers.
  • 5.1.4: A standard 5.1 setup with a front and rear pairs of in-ceiling/ceiling-mounted speakers.
  • 7.1.2: A standard 7.1 setup with a pair of “middle” in-ceiling/ceiling-mounted speakers.
  • 7.1.4: A standard 7.1 setup with a front and rear pairs of in-ceiling/ceiling-mounted speakers.
  • 9.1.2: A 9.1 setup utilizing front wide channels and a pair of “middle” in-ceiling/ceiling-mounted speakers.

5.1.2 5.1.4 7.1.2

7.1.4 9.1.2

Diagrams of all the supported Dolby Atmos configurations using 7.1 through 11.1 channels. Images sourced from Dolby.

Looking at the diagrams, it’s worth noting that Atmos ceiling speakers are located a bit differently from the old front/rear height speakers in current expanded Dolby PLIIz 7.1 or 9.1 setups.  X.X.2 and X.X.4 Atmos setups both utilize in-ceiling speakers located towards the middle of the room, vs. the old wall mounted height channels. As such, consumers wishing to repurpose hardware for a new Atmos home theater may need to reposition their speakers accordingly for the best results. Of course as you might guess, the most convincing effects will come from the X.X.4 systems, which will allow for better front to rear panning of sound effects. However, Dolby is confident that even the X.X.2 setups will yield a significant improvement over non-Atmos configurations.

Dolby claims Atmos speakers do not rely on virtualized processing meaning there will not be a narrow sweet spot.

In-Ceiling vs Atmos-Enabled Reflective Speaker Technology

In addition to the number of channels, there’s also the question of whether you wish to utilize discrete in-ceiling/ceiling-mounted speakers or “Atmos-enabled” speakers utilizing what they call reflective speaker technology. The latter option (of which the aforementioned Pioneer Elite Speakers are an example) adds a separate driver array which is aimed toward your ceiling. The drivers are band limited, and special processing takes place within the Atmos engine to alter select frequencies in order to create the psychoacoustic effect of sound appearing to come from above you. Dolby notes that Atmos-enabled speakers do not rely on virtualized processing like a soundbar, which also means there’s NOT a narrow sweet spot to get the "Atmos" effect.  This is claim is very curious and we look forward to verifying ourselves. 

Dolby Atmos Speaker

Dolby Atmos Speaker - notice the separate connections for the front or rear main channel and the new Atmos height channel.

Shown above is a generic diagram of a typical Atmos-enabled speaker proposed by Dolby.  Notice the driver is recessed into the baffle.  We can't help but wonder how they are dealing with diffraction issues caused by this approach so it will be interesting to pull some measurements once review samples become available.  We also have to ponder how the added mechanical vibrations from a separate speaker integrated into a shared cabinet will affect the overall sound quality of the main or rear channels.

Some manufacturers will be offering Atmos speaker add-on modules to place on-top of your current front and/or rear speakers like this example below from Onkyo.

Onkyo SKH-410 Dolby Atmos Speaker

Onkyo SKH-410 Atmos Speaker Add-On Module

Of course there are important caveats to consider on both sides of the equation. In-ceiling speakers are relatively easy to localize if you’ve got low ceilings (say 8’), taking away from the immersive effect. Conversely, Atmos-enabled speakers are best suited for ceiling heights of 8-9 feet. While Atmos-enabled speakers can work with ceilings as high as 14 feet, Dolby states that the effect does become more diffuse. In addition, your ceiling should be a flat surface (i.e. not vaulted/angled), and be made of an acoustically reflective material such as drywall, concrete, or wood for best results with Atmos-enabled speakers. We’ve also heard that most A/V receivers will require you to specifically select an “Atmos-enabled speakers” option to correctly compensate for sound propagation delays.

5.1.2 Atmos Enabled  5.1.4 Atmos Enabled

5.1.2 and 5.1.4 configurations using Atmos enabled speakers. Image sourced from Dolby. Users wishing to implement a 5.1.2 setup without in-ceiling speakers should utilize Atmos enabled front L/R speakers. Note that this suggests a different "virtual placement" vs. the centrally placed in-ceiling X.X.2 in-ceiling speakers.

Atmos Surround Upmixing: Going Beyond Prologic IIz

Now it’s all fine and good that you can enjoy Atmos with future releases, but a lot of folks already own a pretty sizeable collection of films. What’s in it for them you ask? As it turns out, the Atmos engine also includes a surround upmixer, which replaces the Dolby Pro Logic II family of upmixers. As you might imagine, the Atmos upmixer is a bit more advanced than previous generations. The Atmos engine starts by performs a granular analysis of legacy sources, which can range from good old two channel content to the latest 7.1 Dolby TrueHD mix. From there, the system is capable of steering individual frequency bands from each channel to create up to a 24.1.10 matrixed Atmos environment. Of note: the Atmos upmixer will not send redirected content to speakers between the front left, center, and right speakers in order to minimize the impact on the front stage.

Summary

Ready or not, the market is about to be flooded with Dolby Atmos related gear. To take advantage of the new format, consumers will need to make a significant investment: in addition to new speakers, be they in-ceiling/ceiling-mounted models or Atmos-enabled, you will also need to purchase a new A/V receiver. It’s not hard to see the importance of this to the industry; in the face of declining AV receiver sales, a new theater format which can make use of up to 11 channels of audio is of great benefit to manufacturers, retailers, and installers. Moreover, Dolby Atmos greatly simplifies the creation of movie soundtracks for producers; only a single master mix is required to support all speaker configurations/layouts. So what’s in it for us?  Dolby merely promises the most immersive audio experience yet. Only one question remains: are you ready for Atmos?

Article updated on 8/9/2014 due to the recent release of Dolby's Atmos for the Home Theater whitepaper.

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About the author:

Steve Munz is a “different” addition to Audioholics’ stable of contributors in that he is neither an engineer like Gene, nor has he worked in the industry like Cliff. In fact, Steve’s day job is network administration and accounting.

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Recent Forum Posts:

maseline posts on January 16, 2016 06:55
I was thinking about going with a 5.1.4 but I don't think I have the room for it. The room is only 14x16 and the seating is against the back wall. I already have 2 ceiling speakers directly above the couch. My question is: Will this give a proper height effect? Based on dolby's specs, they should be 30-50 degrees behind the seating area. That is obviously not going to be possible. I plan on installing 2 at 45 degrees in front of seating area. Should I just remove the 2 over the seating area?

Sent from my SM-N910V using Tapatalk
Stephen Novosel posts on January 07, 2016 18:02
Gene, I decided to take up your challenge. I installed discrete speakers on the ceiling. After experimentation to find a dispersion pattern that suited me, I settled on four Klipsch Icon KS-14 surrounds. Their front covers had to be screwed off, and I had to fashion a simple metal strip to ceiling-mount them, but they perform appropriately.

Now, I could say that I am a converted soul – to heighten the drama of my story – but . . . that would be lying. Are discrete speakers “better” than the enabled versions I previously tried? Yes, but. As I noted in my original post, the Dolby Labs Atmos promise is one of those nice-to-have features yet it's nothing earth shattering and would not be missed by 99.9999 percent of those who either cannot or will not adopt the technology whether by way of Atmos-enabled or on-the-ceiling speakers.

There are a few very detailed positive reviews of Atmos from individuals who break down precise moments in scenes from the ridiculously limited selection of blu-rays that encode Atmos. I re-read those posts thinking maybe I missed something because those folks claim it's the cat's meow. I now suspect confirmation bias. Only the recent Mission Impossible film created a sensation of enveloped sound (and only in two scenes) that was apparent to me and to my guest Atmos test subjects.

P.S. – during the Atmos experiment, I also swapped out my three front speakers – going from Klipsch towers and a RC-64 to three of the 650 Ultra-2 THXs. I can report that this one move has had more of an impact on my viewing experience than any other single change I've made in over twenty years of fiddling around dedicated home theaters. To say it was dramatic is an understatement. I am not kidding; there are times now when watching a film that I break into a smile just hearing what these puppies can produce. It's the closest experience to real cinema sound that I know. I encourage your readers to consider buying the 650s before investing in Atmos.
gene posts on October 28, 2015 22:24
First of all, my hats off to you for participating in the great experiment and investing your time and money for the promise of a better tomorrow…today. Dolby is notorious for claiming their next generation tech is a revelation. When DD came on the scene they claimed compression was fine and you had true hi res audio with just Dolby Digital alone. Meanwhile multi-channel music encoded in DTS almost ALWAYS sounded better than its DD counterparts to most professionals and enthusiasts.

Then when TrueHD came, they finally admitted DD was a compromise in sonics due to excessive compression and even at a disadvantage to DTS. TrueHD was actually a quantum leap forward in multi-channel surround. So in that regard, kudos to Dolby for finally having a lossless surround coded. Of course DTS answered back with DTS HD which was equally good though an easier tool for production hence why it became the defacto standard in the industry and dominates Blu-ray to this day.

Now for Atmos, of course Dolby once again claimed it to be a leap forward from even TrueHD. They developed a speaker that fires up at the ceiling and hailed its as “the greatest breakthrough in 20 years”. Most of the press echoed this b/c IMO they simply lack the capacity of critical thought. Dolby went so far as to claim their bouncy speakers are a BETTER solution than discrete ceiling mounted speakers. Again, the press and some manufacturers that jumped on the bouncy speaker bandwagon echoed this as well. What most people don't realize is the vested interest Dolby has in licensing this speaker technology to its partners. Conversely, they don't have a licensing solution for in-ceiling speakers.

The physics don't support the Atmos-enabled bouncy speakers and we've been both skeptical and critical of this since day one. Of course we took a LOT of heat for this from early adopter consumers at AVS Forum and the industry in general. But, we stuck to our guns. We stuck to the facts. We stuck to the science.

Please read:
http://www.audioholics.com/loudspeaker-design/hrtf-and-elevated-sound-dolby-atmos

http://www.audioholics.com/editorials/dolby-atmos-demo

Also check out our YouTube Videos on this topic too:
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That said, if any Atmos-enabled speakers have a chance of at least presenting a reasonable approximation of a discrete ceiling mounted speaker I'd imagine the Klipsch ones would be them. The horn should do a good job of controlling directivity and the speaker has enough sensitivity to keep up with the rest of the speakers in the setup unlike the 4" paper wizzer cones that so many Atmos-enabled speakers are.

My advise to you is don't give up on Atmos just yet. Instead, try to install some discrete speakers either on the ceiling or higher up on the walls above your front and rear speakers. Atmos technology is actually viable and it does have potential to expand your surround experience beyond traditional 5.1 and 7.1 speaker set ups. It's the Atmos-reflection speaker that is the limiting factor in your situation.

Even if you don't install height speakers, you still chose a very good receiver that will handle all legacy formats very well in addition to handling your HD video processing and switching.

Thanks for your invaluable feedback and please let us know how it goes if you take some of my suggestions into consideration.
Stephen Novosel posts on October 27, 2015 07:41
ALL I WANTED

I have a solid month's worth of personal experience with Atmos. I bought eight (8) of the available Atmos-supported Bluray films to use for my testing so I think I have a good sense of the promise vs. the reality. Bottom line for me, it's not worth the effort for the marketed/claimed rewards. This could be primarily because Dolby Labs refuses to support their Atmos technology by explaining how it is to be used or more importantly how its use can be appreciated.

My screening room is 14 x 24 x 9. The ceiling is flat. The room is acoustically treated and includes a 15' screen and projector along with with a host of so-called top-end audio gear driving Klipsch reference line speakers. A Yamaha 3040 Aventage decoded the Atmos.

As with many readers, I conducted due diligence before purchasing the Atmos-enabled Klipsch speakers. Even though I've been in the AV game for over 30 years, my first diligence stop was on Dolby Labs website to read all available Atmos materials; i.e. installation, set up, and placement requirements. Then I visited every other available AV-related website, Blog, and YouTube channel that even remotely discussed Atmos.

The takeaway from my due diligence was that no one – not professional reviewers, nor (incredibly) even Dolby Labs spokespeople/technicians (their interviews about Atmos are on-line if you search) – can say with any degree of certainty how this technology will work in a prototypical (recommended by Dolby Labs) residential Atmos environment. If you listen carefully, and if you read carefully, Dolby Labs hedges all of their claims. The same is true for every other Atmos review out there.

So, how does one decide what to do in light of a lack of consensus about a newer technology? You simply have to buy the stuff, install it, and see if it performs as advertised. Which I did.

Now, I understand the puffery that goes into the development and promotion of marketing claims. But what my wallet will not accept after a $3k+ speaker purchase is a non-responsive, patronizing reply from Dolby Labs when all I wanted was a clarification of statements or omissions they make in their marketing material. My one-sentence question to them was simply: “Should there be a difference in EQ/Bass management for Atmos-enabled upward firing vs. Atmos ceiling downward firing speakers?”

DOLBY REPLIES

“Thank you for your interest in Dolby Atmos home products. Our information shows that you have questions regarding your home system’s compatibility with Dolby Atmos, system set-up requirements, or home speaker placement. Dolby does not provide individualized end-user consultation in these areas. For your convenience, however, we do offer several general resources on our website that may be useful to you. These include: An introduction to Dolby Atmos home technologies (Cinema to Home tab)*. Links to information on many of our partner products.. An on-line speaker set-up guide, with a downloadable PDF speaker set-up guide, and several whitepapers on Dolby Atmos*. Our blog about Dolby Atmos for home theater. We hope you find these resources helpful. You may also wish to consult a leading home A/V retailer or independent dealer/installer for individual consultation on your specific home A/V system. Thank you very much for your interest in Dolby Atmos. * The configurations noted herein are illustrative. Dolby recommends that any overhead speaker installation be performed by professional installers with experience in installing overhead speakers.”

YOU'RE ON YOUR OWN

My $3k+ Atmos adventure is over. I have returned the speakers for a full refund. In my screening room, I didn't “Feel Every Dimension” that Dolby claimed I would. I wasn't "transported into the story with moving audio that flows all around with breathtaking (seriously???) realism“. In short, the experience was a bust with the Atmos-enabled speakers. I would have considered installing ceiling speakers for further testing but not after the Dolby reply. That killed any enthusiasm to engage further. That response, to me, just shows that Dolby either doesn't bother to read customer inquiries, they don't bother to read their own support materials, or worse, they have no interest in ensuring that customers ”get“ the promised benefit. My one-sentence question was derived directly from language in Dolby's Atmos Set-Up pdf.

The hope that Dolby Labs has for the adoption of residential Atmos installations parallels the promises made in the film FIELD OF DREAMS. Dolby apparently believes that all they have to do is build it and we will come. However, the difference is that in FIELD those who ”came“ had a reasonable expectation of what they were going to get. Here we have to take a leap of faith. And you better not expect clarification from Dolby. For if you engage them you will only get passed off to ”consult a leading home A/V retailer or independent dealer/installer for individual consultation on your specific home A/V system“. Hey Dolby Labs – Newsflash! – there are a ton of us out here in consumerland who actually have MORE knowledge than A/V retailers and independent installers, and it is likely only going to be us who would even bother to make the kind of inquiry that I did in the first instance.

Bottom line – Atmos is not a significant enough improvement (not any kind of a ”wow!“ factor which is what I was hoping for) over a good 7.2 or 9.2 installation. I get the underlying ”object" theory behind the Atmos process but in the real world, it just doesn't translate.
AV_Nut posts on September 16, 2014 19:10
AcuDefTechGuy, post: 1051677
When they say “better”, are they talking about the surround channels or the main front 3 channels and subwoofers that will sound better with Object based rendering?

Will the 4 most important channels (Front Left, Center, Front Right, LFE) sound better or just the surround channels?

Will dialogue sound clearer than lossless TrueHD and DTS-HD MA?

I spoke with Mr. Mark Tuffy Ph.D. seconds ago from Dolby. He was the lad who gave the demo at the D&M booth. His cell phone connection was challenging but here is what I got from the conversation.

1. In short the Atmos tools are superior. It's a software platform that will allow mixers to get more aggressive and therefore yield more dynamics both in the vertical and horizontal plane. Basically more wiz-bang effects are being mixed in. So yes, 5.1 and 7.1 Atmos enabled systems WILL sound better so long as the movie mixer took advantage of what Atmos can do. Putting it another way, the platform of tools are not available on discrete consoles.

2. With discrete mixing and for optimum results, your speaker placement should match the mixers to yield the most immersible sound. I didn't really know exactly what that meant but I took that at face value. Since he worked at DTS, Lucas Films, and has his PhD in Signal Processing I figure I will yield to his expertise. He explained matching speaker placement to the mixers placement is never a realistic situation. With Atmos and Object based rendering, you don't need the exact speaker placement to get optimum immersion.

He had other things to say but those are the big-picture cliff notes. In summary, it's a software thing. Every Atmos enabled receiver that processes a Atmos movie WILL be more immersive and impressive (so long as the mixer took advantage of the Object based features). He had complete confidence the consumer will benefit in 5.1 and 7.1. Simply put, Mark said it's audible and noticeable.

Steve with Sound Video in MN
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