It’snot surprising that Dolby Atmos can be a confusing topic, even for enthusiastswho pride themselves on being the “go-to guy” for home theater tips andexplanations when friends and family are looking to upgrade their entertainmentexperiences. There’s just a lot of technical information to absorb, andcountless variables that can confound even the best laid plans. The purpose ofthis article is to provide a general understanding of how Atmos works, and toclarify the best speaker practices to follow when setting up an Atmos home theater. We discuss the minimum number of speakers you need in your home theater to get a proper Dolby Atmos experience.
Tohelp guide us on our way, Audioholics founder Gene DellaSala recently hosted a livestream with John Traunwieser, a recording and mixing engineer forfilm and television, whose credits include work on multiple Star Warsmovies, the Hunger Games franchise, and other big titles. John offeredunique insights from the perspective of a professional whose job it is torecord and mix orchestras at Fox Studios, Warner Brothers, and Sony Pictures inLos Angeles, as well as at Air Studios and Abbey Road in London. John hasworked with many notable composers,including James Newton Howard, John Williams, John Powell, Hans Zimmer, HenryJackman, and John Debney. He also works as a mix tech at the Fox Studiosdubbing stages, assisting several Oscar-winning mixers. His hands-on experienceworking in the Dolby Atmos format helped us to bridge the sometimes sizable gapbetween the intent of the artists and professionals who create our entertainmentcontent, and us — the folks at home who want to enjoy that content in a waythat satisfies our individual needs while simultaneously respecting the effortand care that went into crafting it. Let’s get started with some backgroundinformation on what Dolby Atmos is, and how it works.
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Dolby AtmosPrimer
DolbyAtmos is an immersive surround sound format that expands on previous systems byadding height channels, ideally to be played back by speakers mounted onto orinto the ceiling above the listeners. This allows sounds to be interpreted asthree-dimensional objects placed anywhere within a three-dimensional soundfield. In earlier surround systems, each audio track was assigned to a channel,correlating to a specific speaker. A 5.1-channel system used 5 speakers plus asubwoofer. A 7.1-channel system used 7 speakers plus a subwoofer. Dolby Atmossystems can scale up or down, adding additional speakers as needed dependingupon the size of the room. This means the content is not tied to any specificspeaker layout or configuration.Mixers creating Dolby Atmos content still have the ability to assign a track toa specific channel, using a 7.1.2 format. This is equivalent to a 7.1 systemwith one stereo pair of height channels. This 7.1.2 layout is referred to as the“bed” for Dolby Atmos. But mixers also have the option to assign a track to anaudio “object.” Each object is associated with an apparent source location inthe theater described by a set of three-dimensional rectangular coordinatesrelative to the defined audio channel locations and theater boundaries. Thisallows content creators to precisely place and move sounds almost anywhere,including overhead, to create an immersive listening experience. Duringplayback, the Dolby Atmos system renders the audio objects in real time basedon the known locations of the loudspeakers present in the theater. This way,the audio object is heard as originating from its designated set ofcoordinates. The technology can adapt automatically to take advantage of thenumber and placement of the speakers, whether there are five ear-level speakersand four overhead, or 24 ear-level speakers and ten overhead. For home theater,the gold standard layout is 7.1.4, with seven ear-level speakers, and fouroverhead.
Dolby Atmos Speaker Layouts - 7.1.4 for home (left pic) ; Cinema Layout (right pic)
Thisobject-based system has a number of benefits over conventional multichanneltechnology, in which each source track is assigned to one of a fixed number ofchannels (5.1 or 7.1, for example) during post production. First of all,systems like that did not scale up or down. If you were listening to a7.1-channel soundtrack on a 5.1-channel system, any information being sent tothe two rear surround channels simply wouldn’t be played back on your system.Secondly, conventional multichannel systems required the mixer to makeassumptions about the playback environment, which often didn’t align with thespeaker layout and physical setup of the theater. Object-based technologyallows the mixer more creative freedom and more confidence that, in a properlyset-up Atmos system, the listener will hear the content as it was meant to beheard. From a mixing perspective, Dolby Atmos delivers higher spatialresolution, along with the addition of the height plane, giving the mixer asignificantly larger, three dimensional “audio canvas” on which to build thesoundscape. This space can be used for exaggerated effects flying aroundoverhead, but it can just as effectively be used to add subtle spaciousness, orto increase clarity by moving certain sounds off-screen, or by widening the musicto create an open sonic space for dialogue.
Thefollowing is an excerpt from an explainer from Dolby’s gaming division, goinginto slightly more depth about object-based audio. It describes “static” objects, which are assigned tospecific bed-layer speaker locations, and “dynamic” objects, which can beplaced and moved freely around the three-dimensional theater soundscape. Theseconcepts apply to home theater as well as to gaming.
Thefoundation of Dolby Atmos is based on two types of audio objects: static anddynamic. Static objects are commonly referred to as “bed objects,” as they aredefined as non-moving objects that are mapped to specific speaker locations.Typically, this is a 7.1.2 layout and is referred to simply as “the bed,” whichcorresponds to traditional non-Atmos configurations like 7.1 and 5.1. Dynamicobjects are audio objects that can freely move around the entirety of thelistening field. The bed is essential because it provides a format that isstill applicable for audio that works best in a channel-based environment.Diffuse elements such as ambience, reverb, or anything else that doesn't needto dynamically move around the room would be panned to the bed. Additionally,content that was used in a dynamic object can be folded down into the bed whenneeded, based on prioritization and object management. Dynamic objects are usedfor precise positioning and/or free movement of content within the listeningspace. One of the most immediate features of Dolby Atmos is the ability torepresent sound on the Z axis. … This doesn’t just allow for a height plane, itactually unlocks the ability for sound to be reproduced in its fullthree-dimensional glory. One can take some first steps and place sounds inzones along the listener’sperimeter, such as front, side, back, and above. This is appropriate for mostcontent and can create extremely immersive and compelling experiences. The nextsteps would be to approach design from a layered approach and include conceptssuch as depth, frequency, proximity, perspective into creation of individualassets as well as the scene as a whole.
—Dolby Gaming
Dolby AtmosContent
Whatdoes all of this translate to in real-world listening? A lot of that dependsnot only on the system used to play back the content, but also on the contentit*elf. Not all Dolby Atmos content is created equal. Some titles with “DolbyAtmos” audio use only the bed, with no dynamic objects. In such cases, largerhome theaters with additional speakers don’t see much benefit compared to smallersystems with fewer speakers. According to John Traunwieser, objects are generally used for twothings, and two things only:
Atmosphericsounds that you want to fill the space, filling in the gaps with extraspeakers.
Pointsource sounds. These are sounds effects: things whizzing by, or particulareffects that you want to localize better.
Ifthe mix consists entirely of the 7.1.2 bed, but you have a bigger system withmore speakers — 9.1.6, for example — the Dolby Atmos renderer can fill in thosespeakers, but you won’t hear any unique information in the additional speakersif you don’t have object content in the mix. Here’s a concrete example. Let’ssay you have a large, multi-row theater. Where a typical 7.1.4 layout wouldhave just one side surround speaker on each side wall (to the left and right ofthe listening position), a large theater might have 5 side surround speakers oneach side wall, so that multiple rows of seating are covered. Now imagine ascene in a movie in which a monkey swings down from a tree in front of you,whooshes right past you, and then lands high up in a tree behind you. Thespecificity of the sound in this scene would depend on how it was mixed. If themixer used only the bed and no dynamic objects, you would notice a few things.When the monkey whooshed by you, the sound would pass through all 5 of the sidespeakers simultaneously, so there would be less localization and a lessrealistic sense of movement. If the mixer used a dynamic object for the monkey,the sound would pass through each of the 5 side speakers individually. Thealgorithm is scaled in the renderer, depending on the layout. The seconddifference you’d notice would relate to the overhead sounds. The Atmos bed onlyhas one stereo pair of height channels (that’s the “.2” at the end of 7.1.2).So if the mixer used only the bed, the sounds coming from up in the treetopswould have left-to-right separation, but no front-to-back separation. You wouldsimply hear the monkey move from above, down to ear level, and then back above.If the mixer used a dynamic object for the monkey, you would hear it go downfrom the treetop in front of you, past you at ear level, and then up into thetreetop behind you.
Thereis a lot of static Atmos out there, especially in TV/streaming releases. Thisis usually if the shows were mixed primarily in 5.1 or 7.1, and then up-mixedto Atmos. TV and streaming mixes usually have 1/10th of the time as atheatrical mix, so not enough time is spent on objects.
—John Traunwieser
Thereare a few reasons why an Atmos mix might have limited use of objects. John Traunwieser says that, when it comes to a film’smusic, a lot of soundtracks “aren’treally mixed in Atmos because you don’t wantinstruments flying around the room. If you just stick with the bed, (even) ifit’s an‘Atmos’ mix, you would only be hearing music through the bed. Sometimes, hesays, a mixer might utilize objects for certain strategic things, such asplacing a choir in the ceiling speakers to get it “off the screen,” or to pushcertain sounds wider off the screen so that they’re not in the way of thedialogue. But in many cases, mixers shy away from using objects because asoundtrack rich with object information doesn’t always translate down (tochannel-based formats) in a way that is desirable. Many theaters — bothprofessional cinemas and home theaters — still aren’t equipped for Atmos atall. Atmos titles therefore need to be delivered to the studio in achannel-based format, such as 7.1, in addition to the Atmos mix. And thereoften isn’t enough time or money available to create two totally separatemixes. In fact, budgetary limitations are one of the main reasons why someAtmos titles consist primarily of “bed” material. Creating individual objectsfor dozens of tracks and carefully placing them and moving them around takes alot of time, and time is often in short supply.
Youwould think that something like Star Wars, or any high-budget Marvelshow, or whatever, you’d think that the budget is out the window and you try toget the best result that you want, (but) there are so many factors at play. Idon’t want to tread on any toes, but it’s a collaborative effort, and so youwill do the best that you can in any environment, but sometimes you have manydifferent opinions from many different people. And a lot of films that I workon, they do these test screenings to random people, and then you’re having awhole other set of feedback from random people watching unfinished content. Anddepending on the scores of those screenings, they will go back, re-cut thefilm, re-edit something, re-record the music, do all kinds of stuff. The bestproduct that comes out is when the vision is clear, and it’s executed well, andeverybody respects each other in their expertise. And you get the best resultthat way. … There’s always a budget and a time constraint. Unfortunately, audiois always the end of the process, so the film is finished, and the audio mix isalways the last thing. And for some reason, we operate like high-schoolers inthat everything gets delayed and delayed and delayed, and pushed to the lastminute. And then everybody tries to cram and get everything done to make therelease date.
—John Traunwieser, on the Atmos mix for The LastJedi
Dolby Atmos TheatricalMix vs Near-Field Mix
ManyDolby Atmos movies actually get two mixes; the theatrical mix that is played inthe movie theaters, and the near-field mix for home entertainment. Anybig-budget movie that will be released in theaters will first get a theatricalmix; most of the time and budget are devoted to this mix. If budget allows, asecond near-field Atmos mix for home entertainment is then created. This mix istypically done in a much shorter period of time, though the mixers have thebenefit of a completed theatrical mix to use for reference. Finally, a 5.1/7.1 mix might be made, often in just a day ortwo. Time and budget are the key factors here, but another is the intended useof the movie or TV show. If the title is being made for Netflix, Disney+, orHBO Max, it stands to reason that the near-field mix will get the most time andattention. Sometimes a studio will request a theatrical mix for a streamingtitle, either for archival purposes, or just in case the title ever gets atheatrical release. For some Atmos mixes, the Dolby renderer can do anautomated down-mix to 5.1/7.1, and the results are acceptable. As discussedearlier, this is more likely when there is less use of objects. In other cases,creating a 5.1/7.1 mix from an Atmos mix requires more hands-on tweaking. Accordingto John Traunwieser,mixers don’t always have the luxury of time to listen critically to everyformat and make the necessary adjustments.
So,why the two Atmos mixes? Wouldn’t the theatrical mix give home theaterenthusiasts the best experience? Why make a separate near-field mix? A lot ofit comes down to room size, and the distances between the listeners and thespeakers. Dialing in a mix for a sweet spot centered on just a couple of peopleis different from averaging out a mix for a much bigger room with many morerows. A theatrical mix might not be quite as dialed-infor a single spot, but overall it’s better for more people. And so some of themixing decisions will change based on the environment in which the mix will beplayed back. In a large theater, the seats on the left-hand side might be 75feet away from the speakers on the right side of the theater. And so panningcan’t be as exaggerated, or the people on one side of the theater might miss asignificant amount of information. In a large theater, the mixer might chooseto have dialogue coming out of all three front LCR channels as opposed to justone spot corresponding to the location of the character. In a near-fieldenvironment, where the room is smaller, that’s less of an issue and dialogue willalmost always come out of the center. These are just a few of theconsiderations that mixers must keep in mind when creating a theatrical mixversus a near-field mix for home entertainment.
Mostpeople will only listen to Spotify low quality, or … whatever streaming formatit is, and make criticisms (without) understanding the technology… notunderstanding why it sounds bad.
—John Traunwieser
Dolby Atmos Streaming Quality Compromises
Audioholicsreaders surely know that streaming media can vary in quality depending upon thebitrates and the compression schemes used to transport the digital data fromthe cloud to whatever device you’re using for playback. For example, if you’relistening on any decent audio system, you will hear the difference betweenQobuz (which delivers lossless high-resolution audio) and Spotify, which as ofNovember 2022, has failed to introduce the Hi-Fi tier that it announced inFebruary of 2021. Spotify still uses lossy compression for all streams.Practically all of the other audio streaming services, including Tidal, AppleMusic, and Amazon, offer lossless audio. Unfortunately, lossless audio is NOTthe norm when it comes to streaming video content. Video streaming serviceshave to accommodate 4K picture in addition to audio, and there’s only so muchbandwidth to go around. So while Dolby Atmos audio is offered by many of theleading streaming services (Netflix, Disney+, Amazon Prime Video, HBO Max),your Apple TV or Roku device isn’t serving up the same lossless audio thatyou’d get from an Ultra HD Blu-raydisc, or from a high-end server solution like Kaleidescape. That higher-quality Dolby Atmos ispackaged within the lossless Dolby TrueHD format first introduced with theoriginal Blu-ray format. Dolby Atmos on streaming services is packaged withinthe lossy Dolby Digital Plus format, which uses lower data rates. Atmos audiois particularly affected by the use of lossy compression because, according to John Traunwieser, audio objects in Atmos have adifferent bit rate than the bed channels in streaming media. He says that thebitrate used for objects is “a lot lower than you would think,” and that “ifyou were to mute the bed channels and only listen to the objects, you wouldn’t be very impressed with what you’re hearing.” That’s another reason whymixers often don’t place critical music information in objects. Dolby Atmosmusic can sound great, even when streamed on a device like Apple TV. On aBlu-ray, it can be even better. While some audiophiles will remain devoted totwo-channel content and gear until the Earth crashes into the sun, others —including Chief Audioholic Gene DellaSala — can’t get enough of Atmos music (aka. Spatial Audio).But if you spend any significant time listening to music in the format, it willbecome clear that not all of it sounds very good.
Consumerproducts sometimes outpace professional workflows. It’s like 8K TV. There isn’tany, or hardly any, content in 8K. It’s the same thing with Dolby Atmos. Somany music studios still don’t have Atmos (mixing capability) built into them.So what will end up happening is you’ll mix it in whatever format is there,whether it’s stereo stems, 5.1 stems… and then you send it to a masteringperson who will up-mix and create an Atmos version based on those stems. Onlyrecently, in the last few years, studios have started to upgrade their roomsand get Atmos setups. So there hasn’t been a ton of content. Obviously thebigger titles have studios that have that capability but there is a lot ofstuff out there that has “faux” Atmos, or just up-mixed surround content that wasn’tmixed natively in Atmos. Now you have record engineers that are more savvy toAtmos, who even start recording with more microphones with Atmos in mind.
—John Traunwieser
Howto Set Up a Dolby Atmos Home Theater Speaker System
Withgreat speaker count comes great confusion. Even in the days of 5.1-channelaudio, poor speaker positioning was a common cause of bad sound in hometheaters. With Atmos, a high-performance home theater will likely have 11 ormore speakers and multiple subwoofers, and it’s no wonder that this increasedcomplication causes headaches for those in search of the best performance fromtheir audio systems. Placing the speakers (and seating positions) for a DolbyAtmos theater isn’t hard if you have an ideal room and complete freedom to puteverything precisely where it should go. Just fire up a tool like Audio Advice’s interactive home theater designer and you’ll be done before you knowit. For most of us, however, it’s not so simple. Realistically, setting up anideal Dolby Atmos system has its challenges. The purpose of this guide is notto say that your home theater has to be an all-or-nothing, hardcore megabucksystem to be worthwhile. Instead, it’s intended to help clear up certain areasof confusion, and to help our readers understand which Dolby Atmos “rules” arethe most important to follow, and which ones can be fudged a bit. If you havethe ability to build a perfect spec-sheet Dolby Atmos system, do it! If youhave to work within the limitations of a multi-use living room, you can stillachieve good results if you know what to prioritize. In such situations, anumber of questions will probably arise. Do I really need to place speakers onor in the ceiling? How many speakers do I need? How important is it to placethe speakers where Dolby recommends?
7.1.4 Speaker Layout is the "Gold Standard" for Home Cinema
Asan audio professional, John Traunwieserhas some insight into the importance of proper speaker placement. “That’severything, really,” he said. “When you talk about hearing what the directorintended, the artist intended, they are making those decisions in a room thatis calibrated, and meeting certain specifications that make it Atmos.” As forthe number and configuration of speakers, a 7.1.4 layout is the gold standardthat enthusiasts should shoot for whenever possible. That’s not to say thatit’s the best configuration for everyone. If your room’s front-to-back lengthis on the short side, you may only be able to accommodate a 5.1.4 system. Ifyou have a huge theater, you might benefit from a third pair of ceilingspeakers, additional “wide” speakers for the front stage, and/or multiple sidesurround speakers to provide coverage in a multi-row setup. But 7.1.4 is thelayout that Johnmost often encounters in the studio, and it’s considered the best layout for atypical home theater.
How Many Speakers for Proper Dolby Atmos Playback Youtube Discussion
Some might be tempted to simplify the installation byusing only one pair of overhead speakers, but you need a minimum of fouroverhead speakers — two in front of the listening position and two behind — inorder to recreate the front-to-back movement and three-dimensional localizationthat object-based audio was designed to provide.
Klipsch Atmos-Enabled (aka. "bouncy house") Speaker
Like Gene, John is notimpressed by “bouncy house” reflective-style speakers that sit at ear level andfire upward, with the goal of bouncing sound off of the ceiling to create theaural illusion of height channels. Ditto for Dolby Atmos soundbars. “It’sabusing the (Dolby Atmos) terminology,” John says. “You don’t get the sameeffect, and I wouldn’t know how to judge a mix listening to content through asystem like that.” John’s strong recommendation is to use in-ceiling oron-ceiling speakers, placed as close as possible to Dolby’s officialrecommendations (with a few minor tweaks that I’ll get to momentarily).
Forthe sake of brevity, we’ll assume that you know where to place the 7 ear-levelspeakers in a 7.1-channel system, and we’ll focus on the proper placement ofthe 4 height channels to complete the 7.1.4 Dolby Atmos configuration. (One thingto note is that Dolby does not recommend the use of dipole speakers for thesurround channels in an Atmos setup. These were commonly used in conventional5.1 and 7.1 setups.) If you do need a refresher on how to set up a 7-channel home theater, the Audioholics website already hasyou covered. Here’s what Dolby has to say about the use of overhead speakers:
Overheadsound is a vital part of the Dolby Atmos experience. (The best) solution is toinstall speakers overhead. Most conventional overhead speakers with widedispersion characteristics will work in a Dolby Atmos home theater. Dolby Atmosaudio is mixed using discrete, full-range audio objects that may move aroundanywhere in three-dimensional space. With this in mind, overhead speakersshould complement the frequency response, output, and power-handlingcapabilities of the listener-level speakers. Choose overhead speakers that aretimbre matched as closely as possible to the primary listener-level speakers.Overhead speakers with a wide dispersion pattern are desirable for use in aDolby Atmos system. This will ensure the closest replication of the cinematicenvironment, where overhead speakers are placed high above the listeners. Ifthe chosen overhead speakers have a wide dispersion pattern (approximately 45degrees from the acoustical reference axis over the audio band from 100 Hz to10 kHz or wider), then speakers may be mounted facing directly downward. Forspeakers with narrower dispersion patterns, those with aimable or angledelements should be angled toward the primary listening position.
Theoverhead speakers should be at a height between two and three times thevertical position of the listener-level speakers. The angle of elevation fromthe listening position (to the front and rear) overhead speakers in a 7.1.4reference layout should be 45 degrees. This may be adjusted between 30 and 55degrees if needed. See the related image for the preferred locations of thefour overhead speakers as seen from above. The horizontal width should be aboutthe same as the horizontal separation of left and right speakers, placed at ±30 degrees. If this guidance is followed,the overhead side-to-side separation should be 0.5 to 0.7 of the width of theoverall layout, depending on the distance to the screen and the front threespeakers, relative to the surrounds. It is best to keep the overheadarrangement centered, front to back, over the listening area, even if the frontspeakers and screen are at a greater distance (from the listener) than thesurround speakers.
—Dolby
Theadvice above from Dolby is specific to home theater Atmos systems; theguidelines for professional cinemas are slightly different. John Traunwieser says that the differences between theAtmos home entertainment spec and the Atmos theatrical spec are interesting,particularly with regard to the placement of height channels. “It’s a littletricky,” he says, “because I’m producing content that could be in a theater orfor the home and I have to find a hybrid of both worlds to be able to translatemixes to many different environments.” The differences likely come down toceiling heights. In a cinema, the high ceilings mean that there is a much greaterdistance between the listener and the ceiling-mounted speakers, and between theceiling speakers and the side/rear surrounds.
Forhome entertainment, (Dolby’s) spec is to widen the heights to have them closerto the (left and right) edges of the room. Whereas for theatrical, the heightsare pushed more toward the center of the rooms (again, with regard toleft-to-right distance, not front-to-back). And generally, every studio thatI’ve been in, the heights are generally closer to the center. Because, youknow, it can vary depending on the height of the room, but if your sidesurround speakers are at ear height or a little higher, if they’re too close tothe ceiling speakers, then you don’t get much isolation or separation in thesound, and depending on the treatment in the room and how reflective it is,then it can just blend together and you may as well just have one speakerthere, it doesn’t make much of a difference. So I like to have (the heightchannels) closer to the center, as do most studios, so that you can localizewhat’s coming from the ceiling clearer, and what’s the side channels clearer.
—John Traunwieser
Dolby Atmos Height Speakers Placement Recommendations
Genealso recommends a slight modification to Dolby’s spec with regard to theplacement of overhead speakers, but while John’s adjustment pushes the speakerscloser together laterally, Gene’s has to do with their front-to-backpositioning relative to the listener. As quoted above, Dolby recommends a45-degree angle of elevation from the listening position to the overheadspeakers (with 90 degrees being straight up). According to Dolby, there’s somewiggle room there, and anything from 30 to 55 degrees is acceptable. Generecommends sticking to the smaller end of that range, placing the front Atmosspeakers 25 to 35 degrees forward from the main listening position, and therear ones 25 to 35 degrees behind. (For the record, he also positions themlaterally closer together than the spec dictates, just as John does). Gene saysthat these narrower angles of elevation and tighter formation of overheadspeakers result in a more enveloping sound, as long as you’re using speakerswith sufficiently wide dispersion.
Dolby Atmos Height Channel Angles
Butwhat happens when you run into obstacles? Maybe there’s a doorway where youwant to place a surround speaker, or a light fixture where you want to place anin-ceiling speaker. You might think that these compromises would never affect aprofessional like John, but even pro mixers live in the real world. TheCovid-19 pandemic forced a sea change in the way Dolby Atmos content is created,with many pros setting up home studios and working remotely. By necessity,Dolby even relaxed some of its technical guidelines, allowing mixers to work instudios that weren’t certified using DARDT, the official Dolby Audio RoomDesign Tool. Perhaps one of the reasons why Dolby gives a relatively wide rangeof recommended angles for overhead speaker placement is to allow users some flexibility.(Another explanation has to do with the fact that humans are not as sensitiveto vertical and overhead location cues as we are to horizontal location cues,owing to the simple fact that our ears are on the sides of our heads.) In anycase, how do you proceed when you can’t follow Dolby’s guidelines to theletter? Sometimes you have to place the speakers where you can place them, andat the end of the day, you might still have a pretty good-sounding system. Butif you stray dramatically from Dolby’s spec, you will run into problems. Johnis currently building a home studio, and there’s a fireplace in the room. I don’trecall seeing a fireplace in any of Dolby’s diagrams. Whether you’re buildingan Atmos mixing studio or an Atmos home theater, these real-world challengeswill present themselves. John’s advice is to turn to a professional for help,and that’s precisely what he did. John sought advice from Gene DellaSala andour friendly neighborhood acoustics expert, Matthew Poes.
It’s critical to have a professional knowwhat your room is, and what to work with, and where to place (the speakers).Because the average person wouldn’t knowjust from typing in dimensions and getting a generic placement for speakers. I’m not (rigidly) following the Atmosspec because I have obstacles that I have to get around, but I have theexperience to know, well that’s ok, Ican put them here and it will be ok. So there is a wider threshold for puttingthings in different places. It varies depending on the room size and what youhave in there.
—John Traunwieser
Dolby Atmos Q&A with John Traunwieser
Duringthe livestream, viewers had the chance to ask questions and get straightanswers about topics that sometimes spark confusion or disagreement among hometheater enthusiasts. Some of the questions have been edited for clarity.
Q1.Should a speaker layout match the visual Dolby Atmos renderer on Logic Pro?That is, if the renderer interface shows objects in the corners of the room, doyou need speakers in those locations? Is the renderer of Logic Pro showing avalid spatial map of the recording? What about the virtualization of soundbetween speakers?
John:“Whether it’s Pro Tools or Logic or any other DAW (Digital Audio Workstation),the panner graphic or GUI is just a generic box with dots. It’s not arepresentation of how your room should be laid out. It’s something thatengineers look at to pan whatever, but it’s just a generic box. In Pro Toolsit’s a cube, and it just gives you a general idea of where you’re placingsomething. Ultimately, you’re going to use your ears and pan the sound effector instrument to the location that you want. So (the GUI) is there as a guidebut it’s not showing you what your layout should be.”
Q2.Are there some places where you can’t place objects?
John: “Objectscan be placed wherever you want. All of the speakers can be taken advantage of,using objects.”
Q3.Some people advocate placing height speakers high up on the front and backwalls. Is that desirable, or should they be on/in the ceiling?
John:“Every single studio I’ve ever been to has Atmos speakers on the ceiling.”
MatthewPoes added:
Either could be correct, it depends on the angles. The walls makesense if you had very low ceilings. Otherwise, to get the angles right, theywould need to be in the ceiling. So, the notion that they should be on thewall, or that that’s the ‘correct’ position (is false). That can work OK incertain circ*mstances, but that’s not generally the preferred position.
Q4.What are your thoughts about automatic up-mixing in AV receivers?
John:“We always have a fight when it comes to listening to mixes through consumer(equipment) because there is so much additional processing happening inreceivers that is undesired, especially when it comes to up-mixing. Becausethat’s when you’re completely falling off the map of what the original mix was,and essentially you’re remixing it. If you’re watching a 5.1-channel movie butyou up-mix it to Auro or Atmos, the box is doing something, and it’s everyone’sguess what it’s doing.”
Q5.Is it important to you that people hear a mix the way it was intended to beheard?
John:“The tools are now available to all the consumers to tweak, and people liketweaking with things. And there are a lot of mixes that sound terrible, andpeople think they can make them sound better. And sometimes they do soundbetter. … A bunch of mixers shy away from objects and are very subtle on anyAtmos effects, and some go in the opposite direction and put too much contentin the surrounds. Yes, you’re an artist when you’re creating content and youhave certain freedoms to do wacky things, but it’s ultimately up to people’stastes. Some may like it, some may not. But I think that’s where it comes downto, if it’s wacky then that was the intention. And if you have it set up right,and you hear the content wacky, that’s how the artist intended it to be. If you“correct” that, then it’s different. It may be better; it may be worse, butit’s different. The thing that I will preface is that a lot of people don’tknow if they’re hearing it the way the artist intended, and they’re makingcritical decisions based on (what they are hearing). That’s what drives us(professionals) nuts. People are like, ‘This sounds terrible, or, ‘Who mixedthat? What were they listening to?’ (And yet these people) are not realizingthat maybe the AV receiver was having the ‘Concert Hall’ effect on. Or, you’relistening to something that is such a low bitrate that everything soundscompressed, with no dynamic range, sounds harsh. And I would love for people tohave the ability to hear it how we hear it, because that is the bestexperience.”
Q6.What are your thoughts about Dolby Atmos in headphones?
John:“Atmos in headphones is really behind in terms of being able to pinpoint soundsso that you can tell precisely where they are coming from. Using a generic HRTF(Head-Related Transfer Function) doesn’t give you the localization thatphysical speakers in a room can give.”
Q7.Do you prefer mixing theatrical content, or content for streaming and hometheater?
John:“There are mix decisions that I have to make that are compromises to make ittranslate better to a wider medium. That’s why I like theatrical content thebest because it has a stricter standard of calibration and setup. … When itcomes to consumer products, there’s so much out there, you can’t possibly makeit sound good on everything.”
Q8.How important is system calibration? Can one calibration be used for allformats and source components?
John:“Not all the content you’re listening to is in Atmos. You could be listening to5.1 or 7.1 content through your Atmos system. And if you want to get very granular,if you want to hear it as the director intended, technically you should havedifferent calibrations for different formats. The bass management is differentfor Atmos and Imax and 5.1/7.1. In a properly calibrated room at 5.1/7.1, thesurrounds are down 3dB, so they should be 82dB, not 85dB. When you’recalibrating an Atmos room, everything is at 85dB, so you’re already hearing thesurround speakers 3dB louder than they should be (when listening to 5.1/7.1content). Even going back and forth between an Apple TV and a Kaleidescape, I can’t use the same calibrationbecause they don’t sound the same.”
Q9.You’ve mixed in lots of different studios. Do they all use a standardized Atmossetup?
John:“It’s still the Wild West in studios.Depending on which studio you go to (for mixing), it can be a differentconfiguration.”
Conclusion on Dolby Atmos Best Setup Practices
We’dlike to thank John Traunwieserfor sharing his knowledge and insight. We hope that this discussion helps ourreaders understand how Atmos works, and how that informs the best way to set upa Dolby Atmos home theater. If you STILL need help with your Dolby Atmos Home theater, you can always do a one-on-one home theater consultation with Gene DellaSala, or you cancontact Matthew Poes about acoustic optimization and setup of home studios,dedicated listening rooms, and home theaters.
