The Ultimate Test: Dolby Atmos vs. Dolby Atmos
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Dolby Atmos, for you members of the unwashed and uninformed masses (yeah, you know who you are), enables film sound designers to treat individual sonic elements as virtual “objects” that can be placed and moved almost anywhere within the three-dimensional space of a movie theater. Two things are important about its adaptation for home theater. First, the soundfield—in its original, discretely encoded version, not an extrapolated one—is no longer limited to a two-dimensional plane circling around your ears. The Atmos mix of a movie adds the dimension of height, which means that sound effects can now seem to move anywhere within the space that’s head height or above, including directly over you. Second, each Atmos object is defined by metadata in the soundtrack that describes its position at any given time, which allows an Atmos-equipped A/V receiver or preamp/processor to render best-fit playback based on the number of speaker channels supported in a particular home theater, whether it’s 7, 9, 11, or perhaps (and preferably) even more.
For those who’ve already heard it, Atmos is a significantly uplifting and highly noticeable enhancement over the standard way of doing surround. (Saying it’s the height of movie sound could be a bit over the top, but only if you don’t like puns.) So what’s the best way to add Atmos to your home theater?
Of course, you’ll need to make some changes to your home theater (in other words, spend some money) to accommodate Atmos. The good news is that your current Blu-ray player will most likely be totally compatible if it’s reasonably modern. The less-than-good news is that you’ll have to add or replace at least two—but preferably four—speakers. (You were probably thinking you needed more speakers anyway, right?) The not-good-at-all news is that your existing AVR or pre/pro will likely have to be replaced with one that includes Atmos processing (though some 2014 models are upgradeable now via firmware).
The additional speakers are the ones that will re-create the “overhead” sound. At a minimum, you’ll need two of these height speakers in the front part of the room. Dolby highly recommends using a second pair of height speakers to extend the effect to the back of the room.
A quick side note on nomenclature: The number of Atmos height speakers a system uses is tacked onto the end of the traditional 5.1 or 7.1 (etc.) designation. Therefore, a 5.1-channel system with two front height speakers is written as 5.1.2 to denote the five traditional core channels (front left/right, center, surround left/right) plus a subwoofer (the .1), plus two height speakers (the .2). You’ll need at least seven channels of amplification (i.e., a 7.1-channel receiver or a seven-channel power amp) to drive everything in a 5.1.2 system but the (likely) powered subwoofer. If you add another pair of height speakers to the back of that system, it’s now a 5.1.4 system, with the need for two more channels of amplification. Likewise for 7.1-and-up systems. Atmos is incredibly flexible, by the way. It’ll handle playback through systems with up to 24 discrete floor (roughly ear-height) speakers, along with up to 10 overhead speakers. In other words, 24.1.10, which is starting to look like an IP address rather than a home theater description.
Is Your Room NSFC (Not Suitable for Ceiling)?
Dolby recommends using in-ceiling or on-ceiling speakers for the overhead or height channels in most rooms. With no proprietary requirements, you can use any standard, off-the-shelf models, as long as they’re full range down to 180 Hz or so, have enough output capability, and have wide dispersion. They should tonally match your main speakers as closely as possible, too. On-ceiling speakers pointing straight towards the floor, perhaps small bookshelf or globe speakers, or thin on-wall-style models, are a functional option—though, as with in-ceiling speakers, they’ll require the hiding of cables behind the ceiling for a clean installation.
There will be cases where ceiling speakers aren’t appropriate, though, because: 1) you don’t want to install ceiling speakers; 2) you can’t install ceiling speakers in the optimum locations; 3) you’ve gone feral and live in a cave with a friendly Sasquatch family; or 4) you’re opposed to ceiling speakers on moral grounds. Regardless, Dolby has another option: Atmos-enabled speakers, which include angled, upward-firing drivers designed to bounce the height channel’s sound off the ceiling and toward the listener. At the moment, companies including Atlantic Technology, Definitive Technology, KEF, Onkyo, and Klipsch make Atmos-enabled add-on speakers that sit on top of your current speakers. Klipsch also makes Atmos-enabled combo speakers with integrated Atmos elevation modules, as do Pioneer and Triad. There will be more of both versions from other companies as time goes on.
Your choices of AVRs and pre/pros with Atmos capabilities are good and growing. As of early June, there were at least 19 AVRs that either include Atmos out-of-the-box or are upgradeable via a firmware update, with the least expensive 7.1-channel models starting at €600 list price. (There are deals to be had out there, too.) Brands currently offering Atmos AVRs include Onkyo, Pioneer, Pioneer Elite, Integra, Denon, Yamaha, and Marantz. You can get a pre/pro with Atmos from Onkyo, Integra, Marantz, Steinway Lyngdorf, and Trinnov, but you’ll need to budget a little more for one of these because they start around €2,500—and remember, you’ll need additional channels of amplification for the overhead channels as well. If you’re on a really tight budget, Onkyo has a couple of home-theaters-in-a-box with limited Atmos capabilities, which you can snag for something in the range of €900 to €1,200.
Where Are the Atmos Blu-rays?
Once you have the hardware, what are you going to watch? By the end of this year, more than 160 movies will have been mixed in Dolby Atmos. That’s great—for the movie theater-goers. But as I write this in early June, there are only eight Blu-ray movies that include an Atmos soundtrack. OK, nine if you count The Expendables 3 as a movie. Ten if you throw in Dolby’s demo disc. (I’m only counting Region 1 BDs here, by the way.) Bizarrely, none of the discs (except for the demo) touts the Atmos soundtrack on its cover. You have to look for the tiny Dolby Atmos logo or find Atmos mentioned in the miniature type of the feature listing. Surely—please, pretty please?—by the time you read this, there’ll be at least a few more Atmos-encoded discs on the market.
You don’t need a new BD player (or new HDMI cables, thank goodness) because Dolby developed a new algorithm and new extensions for Dolby TrueHD and Dolby Digital Plus to include the Atmos encoding while retaining backwards compatibility with non-Atmos gear. A lot of streaming video services use Dolby Digital Plus, which means you can look forward to being able to stream movies with Atmos soundtracks. As a matter of fact, Dolby says that Vudu and Amazon intend to start streaming Atmos-encoded movies; when that’s going to happen, however, hasn’t been announced yet. Go online now, and the only Atmos items you can stream or download from either provider are Dolby demo clips. (Yeah, baby, demo clips!)
Go Take a Height
Dolby has fairly specific guidelines concerning when to use in-ceiling or Atmos-enabled speakers, as well as where to install or place whichever type of speaker you use. I’ll quickly talk you through the basics.
A 5.1.2 Atmos setup with left and right ceiling speakers (number 6 on diagram).
Another 5.1.2 Atmos setup, this one with left and right Atmos-enabled speakers (number 2 on diagram).
To begin with, unlike a speaker system’s center and surround back channels, Atmos speakers are always added in pairs. If you’re only able to use one pair of overhead speakers, they should always be used for the front overhead channels. It’s OK to mix speaker types, if appropriate, by using a pair of ceiling speakers for the front overheads and a pair of Atmos-enabled up-firing speakers for the rear overheads—or vice versa. (Mixing left and right speaker types, on the other hand, is very, very not OK.) Note that your AVR or pre/pro will send a somewhat different signal to your ceiling speakers or Atmos-enabled elevation modules depending on the type used, to ensure they provide the optimum effect.
In an average room with a typical 8- to 14-foot-high ceiling, Dolby says the preferred setup uses ceiling speakers. In a four-overhead-speaker setup, you’d install the front pair of ceiling speakers between the listener and screen, and place the rear ceiling speakers slightly behind the listener. In a system with only two overhead speakers, you’ll mount them in the front of the room, but ideally in somewhat closer proximity to the listener than if you had two pair of height speakers (see diagrams). For most speakers that have a reasonably wide dispersion pattern, they should be firing straight down. But if you’re stuck using speakers designed with a more narrow dispersion pattern, and they feature “aimable” drivers, Dolby recommends directing them at the listener. The locations of the remaining listener-level speakers in a 5.1.4, 7.1.4, or 9.1.4 system stay roughly the same.
A 5.1.4 setup with four left and right ceiling speakers (numbers 6 and 7). Note the more forward position of the front height speakers compared with a 5.1.2 ceiling-speaker system.
A 5.1.4 setup with four left and right Dolby-enabled speakers (numbers 2 and 5).
When you use Atmos-enabled combo speakers or Atmos-enabled add-on modules, speaker placement is nearly identical to the standard arrangements for 5.1, 7.1, and so on, though if your existing surrounds are mounted much above ear level, you may want to consider lowering them a bit to ensure enough distinction between side/back and ceiling effects. The front left and right Atmos-enabled speakers simply replace your current front speakers. When you use add-on modules, ideally they should be placed on top of the existing front speakers. The back pair of Atmos-enabled combo speakers (or add-on elevation modules) for a 5.1.4 system should replace (or sit on top of) your original in-room surround speakers. In 7.1.4 and 9.1.4 systems, the Atmos speakers (or modules) should replace (or sit on top of) the surround back speakers.
Confused? Don’t sweat it, because now we’re going to move on to the less-convoluted topic of the equipment I used.
Atmos.2 or Atmos.4?
As I’ve mentioned, Dolby says using ceiling speakers is the preferred setup—for most rooms. In some cases, they note, “experts” have found that Atmos-enabled speakers sound just as good. By virtue of the fact that there’s essentially no labor involved in setting up Atmos speakers or add-on modules (other than running an extra set of speaker wires), it’ll usually be cheaper and easier to go the in-room route, rather than the in-ceiling path. What we wanted to find out was just how audible the differences are among the various setups. How much surround sound or basic sound quality, if any, do you sacrifice if you use Atmos-enabled rather than ceiling speakers? For that matter, what’s the difference between using only two front height speakers versus four? We also thought it would be cool to discover just how time-consuming and confusing it could be to compare all these variations.
Considering the fact that Atmos speaker systems can range from the most basic 5.1.2 configuration up to a room-filling 24.1.10 speakerpalooza, a person (as in me) could spend years testing the different configurations. Editor Rob Sabin knows I always turn my stuff in way past deadline, but even he wasn’t comfortable with the thought that I’d take a year or two to complete the project. So we set our sights on something more reasonable and decided to compare the performance of four systems, using the following Atmos configurations: 1) 5.1.2, with just one pair of ceiling speakers in the front; 2) 5.1.2, with one pair of Atmos-enabled combo speakers in the front; 3) 5.1.4, with pairs of in-ceiling speakers in the front and rear; and 4) 5.1.4, with pairs of Atmos-enabled speakers in the front and rear.
It may sound like a simple task, but switching from a 5.1.2 Atmos in-ceiling configuration to a 5.1.2 Atmos-enabled in-room system was, um, a bitch that involved much more than merely swapping speaker cables. (It was an even bigger hassle switching between the 5.1.4 arrangements.) Since Atmos playback rendering is done based on the number of speakers and their types, any layout or component changes had to be accounted for in the Yamaha AVR’s less than smoothly intuitive speaker-setup menu. Distances and output levels had to be checked and adjusted each time, too (thus, the overworked sound meter).
My home theater is 12 feet deep and 24 feet wide, with a typical 8-foot-high drywall ceiling. It’s not quite an average room because there are two sets of exposed beams on the ceiling and side walls that split the room lengthwise into thirds, so I couldn’t always locate speakers—especially the ceiling ones—in the absolutely optimum, primo-of-primo spots. Fortunately, though, after cutting a couple of new holes for the ceiling speakers, I was able to stay within Dolby’s recommended parameters.
I thought about adding acoustic treatment to the ceiling. Eric Smith, the founder of Auralex Acoustics, has spent a lot of time looking into how to properly treat a room to get the best performance out of an Atmos system—especially one with upward-firing Atmos-enabled speakers or add-on modules. He was extremely helpful in coming up with a plan of attack that would have included movable and/or removable acoustic panels for adjusting the acoustics based on the Atmos speaker type. In the end, though, I decided against using any special treatment in order to keep the results as close to what you’d get in the average living room or home theater.
On a Knife’s Edge
It would have been utterly insane to compare all four of the Atmos configurations using as many movie scenes as we usually do when reviewing a single piece of gear or one speaker system. I ended up choosing chapters 7 and 8 of The Hunger Games: Mockingjay, Part 1, along with chapter 11 of Teenage Mutant Ninja Turtles. The former selection has a nice mix of subtle and bold effects, while the latter has…well, let’s just say there’s nothing subtle about Teenage Mutant Ninja Turtles.
That said, whatever you think of the storyline, TMNT has one of the best examples of how cool Dolby Atmos can be. In chapter 11, when Splinter (a talking, mutant, ninja-master rat) fights Shredder (an evil ninja master wearing what looks like a ninja version of Iron Man’s suit)—if you haven’t seen the movie, just go with it—Shredder fires a series of knife blades through the air at Splinter. Splinter dodges the flying blades, and they get stuck in the wall behind him. Fortunately for Shredder, his suit magnetically draws the blades back to him. At this point, it just so happens that the listener is sitting between the blades and Shredder. With the Atmos-encoded soundtrack, the sounds of the blades don’t pan from the front left speaker to the rear left. Instead, they seem to fly through the middle of the room, past your head. If you’ve ever seen a 3D movie where a snake head or a spear or something appears to come out of the screen toward your face, this is the aural equivalent of that experience—without the cheese factor.
How do I begin to describe the differences among the setups? In this case, the 5.1.4c system (with “c” being my unofficial shorthand for ceiling speakers) performed phenomenally. The blades, especially the last one or two, were so acoustically fully formed and solidly placed as they moved from the screen to the back of the room that I had the urge to duck out of the way. I’m not sure how to quantify a three-dimensional sound element—I now understand why Dolby refers to it as an “object”—but this had all the acoustical aspects of the real thing. In comparison, with the 5.1.2c system, the blade was fully formed when it left the screen, but it seemed to dissipate slightly as it moved toward my head—and then it “disappeared.” The 3D soundfield flattened when it reached my head. In terms of 3D-ness, it reminded me of the limitation common to a lot of soundbars, whose soundfield never extends past the listener.
Next, I switched to the 5.1.4e system (again, my unofficial shorthand, with “e” referring to Atmos-enabled speakers). As Dolby has predicted, it performed nearly as well as the 5.1.4c ceiling system in terms of acoustic 3D-ness. In fact, the knife blades were just as fully formed and moved through the air the same way. The main difference I heard was in the sharpness of the sonic image. Instead of having the surgically sharp edge, these blades “sounded” like they’d been used a couple of times. The 5.1.2e Atmos-enabled system had the same subtle characteristic, but as with the 5.1.2c system, the 3D soundfield dissipated abruptly.
How High Can It Fly?
My notes describing the number of noticeable differences among the systems during chapters 7 and 8 of Mockingjay were copious, but I’ll keep it brief here. In the beginning of chapter 7, a hovercraft flies overhead and lands. With the 5.1.4c ceiling system, the swoop of the wind around the room during the landing was amazing and felt like it could easily blow my hat off (if I were wearing a hat). The 5.1.4e Atmos-enabled system definitely created a swirl of wind around the room, but in some way it didn’t seem quite as powerful. Both the 5.1.2c and 5.1.2e systems reproduced a sense of width and depth in the front of the room, but as with the scene in TMNT, it collapsed at my seat.
After Katniss and the rest of the group leave the hovercraft, it takes off and flies into the distance. Here, another interesting difference became apparent among the speaker setups. With the 5.1.4c ceiling system, there was a clear sense of a three-dimensional hovercraft taking off in the front of the room, and the sound of the craft gradually got smaller and smaller, as well as higher and higher, as it traveled out of the left front of the room. The 5.1.2c ceiling system with just two height channels was able to nail that effect, too, but because of the shortened 3D soundfield, it felt more like I was sitting at the edge of the action rather than in the middle of it. When I listened to the 5.1.4e Atmos-enabled system, the main difference I noticed was that the craft didn’t seem to go as high as it flew away. Instead of the wide-open feel of the 5.1.4c system, there was a subtle sense of being in a more limited area, almost like being in a large bubble.
These patterns repeated themselves during numerous other scenes in Mockingjay that included travelling effects: A sense of total sonic openness with the 5.1.4c in-ceiling system; a large-but-limited bubble with the 5.1.4e Atmos-enabled system; being on the edge of the action with the 5.1.2c system; and solid front-stage width and height that collapsed at the listening position with the 5.1.2e system. There was also a slight edginess to some of the music and off-screen voices on both of the Atmos-enabled speaker systems during the scene where Katniss walks into the makeshift hospital, for example.
So, after all those comparisons, what’s the bottom line? Well, first of all, Dolby’s right: Using four ceiling speakers for the overhead channels makes for an awesome, theater-worthy experience—and that’s with a 5.1-channel system as the starting basis. A system with four Atmos-enabled speakers is still a fantastic alternative. The subtle issues I had with the scope of the soundfield and the slight harshness of certain sounds might well be resolvable with a small amount of acoustic treatment, so you may not be sacrificing much if you can’t use ceiling speakers. Dropping down to two Atmos overhead channels in the front (either ceiling or Atmos-enabled) definitely isn’t as good, but it’s still a dramatic improvement over a non-Atmos system.
To tell you the truth, before I set out to test these configurations, I wasn’t really all that sold on Dolby Atmos for use in home theaters. All of the demonstrations I’d sat through had been at trade shows, such as CES. Under those types of conditions, angels could be singing, and you’d walk away saying, “Meh.” Now that I’ve experienced Atmos in my home, however, I’m hooked. Of course, I want the full configuration of four ceiling speakers, but I’d be happy with any of the other setups as well. Atmos really does add another dimension to the movie experience, and I mean that in more ways than one.
With only a handful of Atmos-encoded Blu-rays available (seriously, I can hold all of their cases in one hand), I can’t say you should drop several thousand dollars and upgrade your system immediately. And the recent emergence of yet another competing object-based surround system, DTS:X, would seem to confuse matters for potential buyers. Fortunately, DTS was clear in its announcement that DTS:X will adapt to any speaker placement configuration, which suggests that DTS:X-encoded content played through an AVR or surround processor that handles both formats should work fine with an Atmos speaker layout. Only time will tell how true that is. But the first AVRs offering Dolby Atmos and DTS:X processing will be available by the time you read this, and it would appear that one well-planned system update may accommodate both.
So, let the games begin, and let the new object-based titles pile up. As more Atmos discs appear, along with more Atmos-enabled speakers and components, you’ll probably decide that it’s “high time” to give your home theater a makeover.
Article by Daryl Wilkinson.
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