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Ten Speaker Layout Tips for Dolby Atmos, DTS.X & Auro

Dolby Atmos has been a big thing with our client base. Since the format was announced >80% of our theaters have been designed to support Atmos and other next-generation audio formats such as DTS.X and Auro.

Here are some of our learnings and recommendations based on these experiences:

    • Ensure there is a clear line of sight from all surround speakers to all seats.  Just because we have some new audio formats does not mean we should throw away the good speaker layout practices from the last 20 years of surround sound. High frequencies are easily blocked by seat backs, heads and other obstructions. To get balanced direct sound you need a clear line of sight to the speaker from each seat.

 

    • Do not put surrounds at ear level. See above. CEDIA (the industry trade association for contractors in the home theater design and installation market) is going to be updating their recommended audio practices to reflect this exact point later this year.

 

    • Keep surrounds as low as they can go without causing other issues (e.g. too much SPL variation over audience). Why? Because you want to keep the separation between the bed layer (the lower set of speakers) and the height layer (the ceiling speakers).

 

    • Make sure surround speaker locations work for the speakers you are using and their coverage pattern. Don’t use dipoles for spatial audio, as by design they do not provide consistent coverage or support localization in the dipole “null”. If you are using narrow dispersion horns for surrounds then make sure will provide adequate coverage of each seating row. This is not really a new requirement, but with spatial audio being able to localize discrete effects in the surround field is more important.

 

    • You may need to use “pan and tilt” speaker mounts to direct speakers at the right place (not necessarily the main listening position; there may be other locations that work better for best coverage). If you have two rows then a position between the two rows often works best in terms of where to point the speakers.

 

    • Place ceiling speakers so they meet published standards but also provide good front to back angular spacing.  See below.

 

    • If the front LCR and rear surrounds are raised above 0 degrees (likely) then the position of the ceiling speakers should change to provide more even spacing front to back. The screen LCRs are often raised above ear level in most dedicated theater in order to provide a good direct sound field to the second row. The rear surrounds are also often raised in order to provide clear line of sight over the seat backs of the second row to people in the first row. If you follow the Dolby Atmos layout angles exactly in this kind of configuration then you won’t have much angular separation between screen and first ceiling row and between rear surround and back ceiling row.

 

    • More than two ceiling rows may be necessary for best coverage. If you are trying to provide a consistent experience in a multi-row home theater then you may need a third set of ceiling speakers. Generally you would position the first and second row of ceiling speakers based on the angles for the first row of seats. But if you do this then the second (and other) rows may have less-than-great angular spacing front-to-back (see above). A third row often helps ameliorate this issue.

 

    • Ceiling speaker coverage requirements are challenging and with the exception of a coaxial there are going to be coverage holes due to crossover lobing and other things that need to be worked around. Ideally you need speaker off axis measurements (both horizontal and vertical) to do this. The main challenge is the need to provide great coverage both front-to-back in the room and left-to-right. This requires that ceiling speakers have a conical dispersion pattern. Most speakers are multi-way designs, using separate high and low frequency elements. These often have off axis phase cancellation issues, and it is important to know where these are. Speaker manufacturers are playing catch up with the dispersion requirement for spatial audio formats at the moment, so there isn’t much out there that really fits the bill for ceiling speakers. Note that we see many using mis-matched sets of speakers for spatial audio, such as LCRs and surrounds from one manufacturer and in ceilings from another. For spatial audio this is a big mistake, because soundtracks will increasingly have audio objects (the key part of these next generation formats) that can move from any speaker to any other. You do not want the timbre of that sound to change as it changes position spatially.

 

    • You may need to use pan and tilt brackets on the ceiling too. Because of the dispersion requirements, you may need to angle and point the ceiling speakers to provide good audience coverage.

 

35 thoughts on “Ten Speaker Layout Tips for Dolby Atmos, DTS.X & Auro”

  1. I have really been struggling with figuring out the proper surround speaker height placement. Your first three bullets seem to contradict each other. The Dolby Atmos specs say to place the surrounds at the listening level but that would most certainly mean that someone sitting next to you will block the sound coming from them. How do we reconcile this? It’s very confusing. Thanks!

    1. Hi Bill, thanks for reading. The first three spatial audio layout tips are not contradictory if you ignore what is written in the Dolby Atmos specifications. Basically put the surround speakers as low as they will go whilst still maintaining clear line-of-sight to each listener. There is a CEDIA working group involved in updating recommended practices for spatial audio, and they are recommending NOT to follow the “put surround speakers at ear level” part of the specification. Hope that helps, please post any follow up questions!

      1. Nyal, that helps a lot. Thank you for the reply. It just didn’t make sense to me for Dolby to recommend putting speakers at ear level. That would really stink for the poor guy in the middle of the row! In my room, I need the speakers about 2 feet up from ear level to provide line of site.

        Another issue is that my front speakers are right at earl level (the tweeter I mean). Will this cause a problem when my surrounds are basically 2 feet higher than those? Also, do you still recommend that surround backs and surround sides all be at the same level? I tend to think about the speaker heights in terms of angles, not distances. Distances just don’t make sense when the side walls are at a different distance from the main listening position that the back walls. My rear walls are double the distance from the MLP than the side walls, if I put them all at the same height, that would mean the sides and rears are at greatly different elevations. Does that make sense?

        Thanks

  2. Hi Nyal.

    Great article. Some questions if I may.

    1- When adjusting the position of the overhead speakers to compensate for higher placement of the traditional bed layer speakers. Would it be best to adjust all the speakers together or by keeping the ratios constant or would you recommend just moving the nearest set accordingly?

    By this I mean, for instance, my SBR&SBL pair will be 10deg above ear height. So would you recommend to a)move only RHR&L forward 10deg or b)adjust all the speakers forward by 10 deg or c)move all speakers but keep the separation ratios the same – so from 45deg for FHR&L and RHR&L the spacing goes from 45:90:45 to 42.5:85:42.5.

    2 – Does this concept also work across the room when taking into account the RS and LS speakers also being above ear height? Should the overheads then be moved closer together, or kept in line with the FR and FL?

    Actually, working on the basic concept of a stereo pair and given that currently we’re unable to tell the processing component (engine?) which angles we are using. Would it be best to just work up from the bed layer in all directions and equally space the height channels keeping all the angles the same. So for sake of ease, say all bed speakers are at ear height. Would the best separation be with 60:60:60 front to back and also side to side. I guess the ideal separation would be to mirror the mixing studio layout. But which angles do they use…

    Kind Regards.

    Andy.

    1. Thanks for reading!

      I would advise adjusting all speakers so that the angles between speakers provide consistent coverage. At minimum you want 30 degrees separation between bed surround and ceiling. You’ll end up with a large hole between the two rows of ceiling speakers (it’s 90 degrees in the Atmos layout drawings). Ideally we’d have another ceiling row to provide better angular coverage front-to-back.

      You should also consider what the angular coverage looks like across the width of the room. However you also want to make sure the ceiling speakers are placed for smooth front-to-back pans.

      There are no “hard” guidelines, you have to lay things out for each room, where the seats are, how many channels you have, etc.

  3. …or d) shift RHR&L forward 10deg and FHR&L back 10deg, thus keeping centrally located height objects central.

    Hmm, it appears that unless you have one seat in the ideal position in an ideal room, you have to choose between accurately smooth panning objects or accurately placed objects…

    1. If you have enough speakers then there is no compromise. That’s the benefit of using 16 or 24 or 32 channels. Not only does the MLP have a great experience but other seats do as well.

  4. Thanks very much Nyal.

    Ok, so when an object pans overhead in an Atmos track. That extra separation as suggested by Dolby is part of the mix. So the transition from bed to overhead is relatively faster than from overhead to overhead. Thus the overall effect is a nice steady pan. Moving those channels physically closer together would effectively mean that the pan speeds up in the middle and this is why we should aim to keep the ideal ratios that Dolby suggest and shrink each angle accordingly?

    So in order to have a smooth pan in a more ‘regular’ home theater (wish I had the room for 32 channels!) you have to keep the ‘ratio’ of the Dolby recommendations the same and position the best seat forward into the centre of the overhead channels or alternatively lift the LCR?

    How does moving SR and SL forward of the MLP affect things 🙂

    Kind regards.

    1. Hi Andrew…interesting point about keeping the ratios consistent, I had not considered that. The ratio in the “ear height” layout is 1:2:1 (45 bed to overhead, 90 from overhead to overhead, 45 overhead to bed, all front to back). After laying out a number of theaters I’m leaning towards layouts that can be expanded to a 9.1.6 setup, with wides and 6 overheads. In a 6 overhead situation the ratio is 1:1:1:1, i.e. take the angle from fronts to rears and divide by four, and use that angle between each speaker.

      SR / SL should be behind the first row in a modern layout to allow room for the wides. Previously I was putting SL/SR slightly ahead, at say 80 degrees, but with wides a position around 100 degrees makes more sense. Then with wides you have 0-50 (wides)-100 (sides)-150 (rears) or 0 – 55 – 110 – 155.

  5. Hi Nyal, I’m currently doing a 9.1.6 layout in a 12x12x8ft room with a single row of two seats. I have two different options when it comes to the bed channels 0-25-50-100-142 or 0-30-60-100-150. The heights will be 45-80-125. I use a 60″ flat panel TV that will be upgraded to a 65″ OLED at some point. Which layout would you recommend?

    1. Laterally: 25, 50, 100, 150?

      Vertically: depends on the vertical angle of your LCR and rear speakers…divide the remaining angle equally.

      Ensure you pay attention to the dispersion characteristics of the speakers, which may mean angling some. Target -3dB at 4kHz or better relative to on axis.

  6. Nyal,

    Very informative post. I’m upgrading to Atmos with a 11-channel receiver. I’ve been struggling between 9.1.2 and 7.1.4. Most seem to choose 7.1.4 but I really like the filling in of the gaps between fronts and surrounds that have always existed. Do you recommend one over the other? Also, someone above mentions 9.1.6; how is this possible with current receivers?

    Most importantly, Dolby shows ceiling speaker placement almost completely on the side of the ceiling where I would have thought they’d be much more centered. What is the reasoning for this and should ceilings be on axis towards center or straight down?

    Thanks for your time and knowledge.

    1. I don’t know of any receivers that will do 9.1.2 … to my knowledge everything is 7.1.4 except if you go to the very high end pre-pros (Datasat or Trinnov).

      Dolby recommend about 30 degrees minimum angular separation between the surrounds and ceiling speakers. The idea is to spread the speakers out both front-to-back and side-to-side so that you get consistency of coverage. Remember that a phantom image only works to about 60 degrees angular separation (at least in the front lateral plane), beyond this the sound will jump from one speaker to the other without smoothly panning through it.

  7. Nyal,
    Though I’m struggling to keep up, these discussions have been as helpful as anything as I try to design my 7.1.4 Atmos system (ceiling firing). I’d certainly appreciate your thoughts on my proposed speaker setup. I will have two rows of seating and my origin point is the center of the first row. (Room is 15’ wide, 13’ deep, 9’ high)
     To maintain 30 degree separation and have my sides slightly behind the first row I propose the following: front ceilings at 65 degrees; side surrounds at 95 degrees; back ceilings at 125 degrees; rear surrounds at 155 degrees.
     The surrounds will be as low as they will go with a clear line to all seats. I’m assuming the rear and side surrounds do not need to be on the same level.
     The ceiling speakers will be aligned with the front left/right speakers (as per the Dolby diagram)
     My plan is to raise the front L/R speakers (probably Martin Logan 60XT) with stands 12” to 16” high. (Want to improve lines of sight but concerned about separation from surround bed and ceiling speakers.)

    Very grateful. Basil.

    1. Seems like you have a good grasp on things…but you should definitely sanity check the dispersion coverage of the speakers you are planning to use. If you are using Martin Logan Electromotion in-walls, note that they don’t have great dispersion (a limit of the AMT design)…it’s around 80×80 at high frequencies. That means I would try and keep all seats (or at least all key seats) no more than 40 degrees off axis, and preferably no more than 20 degrees off axis…see Dispersion Requirements for Dolby Atmos (beware, somewhat technical…)

      I’ve done a theater with ML 60XT before, and yes, I ended up raising it on a stand and also blocking the ports. It was placed behind an AT screen in a baffle wall. The acoustical center of the speaker wants to be 1/2 to 5/8 screen height.

      1. Thanks Nyal. Very helpful advice regarding the Martin Logan speakers. The Martin Logan rep with whom I talked was pushing the Electromotion speakers, but for the ceiling, the Helos 22, with its wide dispersion (though curiously, no spec), seems to be the better choice. I’ll probably also choose the Motion FX instead of the Electromotion FX-2 for my surrounds because of the dispersion specs. Great catch, and again, many thanks.

        1. Helos vs EM for ceiling would depend on the speaker position relative to the seats. Certainly for the front ceiling row EM is probably the better choice. For the rear ceiling row the angled orientation is not great if you have two seating rows….better to do a speaker that’s pointing downwards. What I’ve done before is used EM-IC for the front ceiling and EM-IW for the rear.

          1. HI Nyal,

            I’m looking at getting 4 Martin Logan IW speakers for the surrounds (left Sur, Right Sur, SBleft, SBright). I will only have 1 seating row. Do you think tis would sound pretty good?

          2. Let’s see…

            1. Follow speaker placement recommendations: http://www.acousticfrontiers.com/2013314speaker-layout/

            2. Check resulting speaker placement against speaker dispersion specification: http://www.acousticfrontiers.com/dispersion-specifications-and-off-axis-response-plots/. If you are using the Electromotion IW those are quoted at 80 degrees coverage, so for best results position listeners no further than 20 degrees off axis (or as the measurements reveal as described in the linked blog post)

            3. Timbre match to LCRs. Ideally this means using speakers from the same “family” i.e. same / similar drivers and conscious decision by the manufacturer to timbre match.

            4. Position vertically in the correct location (see the recommendations in this article, particularly bullet points 1-3)

  8. What about the crossover settings I have enabled front speakers on top of my floor standing speakers klipsch all around including 7.3.2 onkyo 1030 reciever

    1. You should review the settings recommended by the manufacturer. I believe most Atmos enabled speakers need a quite high crossover point (120Hz?).

  9. Good info I live in a condo apartment . I have the speaker configurations for ATMOS 5.1.2 one pair of tops on my ceiling front . AURO at 10.1 my receiver as a stand alone does nine but for the tenth channel it’s runned by a separate amp. DTSX I select 9.1 my AVR can give me back surrounds but my room doesn’t support good for that my home theater is designed sideways not vertical . My AVR is Denon . Andrew .

  10. Really happy to find this article. Did CEDIA ever publish guidelines on this topic? I am just moving to Atmos. My theater room has pretty much impossible to change acoustic panels and moving my 4 surround speakers horizontally or vertically is going to be minimally difficult and quite expensive. I am hoping I am not too far off of the CEDIA guidelines as the Atmos guidelines clearly do not anticipate stadium seating (I only have two rows, but nonetheless).

    1. The CEDIA guidelines have not been formally published, but have been available to CEDIA members for well over a year. The CEDIA guidelines include provision for tiered seating. Essentially you position the ceiling speakers for even front-to-back and side-to-side coverage…because the front stage and rears are often above ear level you don’t have 180 degrees front to back anymore, so you divide up the angle evenly. Optimally you’ll likely end up needing 15+ channels for consistent coverage, though today most AVRs and pre-pros max out at 11 channels.

      Note that the room acoustic treatment will likely need to change for spatial audio. Surround localization rather than just envelopment becomes more important with spatial audio soundtracks, and so the acoustic design needs to become more absorptive and also be as consistent as possible for the surround speakers.

      If you want to do it properly and are aiming for the best results then you may want to consider the upgrade to spatial audio as a major theater remodel, rather than just tacking it onto what you have now and hoping for the best.

  11. Hi Nyle
    Will a CD horn with a wider dispression 90 *90 ( jbl pt wide coverage wavegiude from Jbl AC16) is preferred on a 90*50 horn for atmos (18 sound XT120)?
    I have a single row position 30 deg to ceiling speaker The vertical plane if the horn covers the front to back and I have wooden floor. The room is relatively small 21*16*8
    I am planning to build my own speaker and use a simmular compression driver used for my front LCR speakers qsc sc 1120.

    1. If you can point the speaker at the listening position then 50 degree dispersion may be enough, but I’d suspect 90 degrees would be better. You’d have to map it out in CAD to know for sure.

  12. Thank you for this article, pretty helpful. I have a question, I am setting up a 5.1.4 configuration in my family room with 4 ceiling speakers for atmos (and thankfully based on what I just read my surrounds are just above ear level).

    My concern is the fact that I can’t move my couch forward so my seating position is pretty much against the back wall, I seem to be getting conflicting info as to whether I can still use a 4 ceiling speakers or just 2. From what I have seen published by Dolby, optimal placement for a .4 setup is with one set of speakers is ahead of you while the other should be behind you.

    Any suggestions? my installer is coming in a couple of days and i’d like to decide if i’m doing 2 or 4. Not sure if this helps but my AV receiver supports Audyssey MultEQ XT 32 calibration.

    Any assistance would be greatly appreciated.

        1. Unfortunately not a great place for speakers. You need minimum 3′ preferably 4′ to prevent surround speaker localization (i.e. speaker blaring in ear syndrome).

  13. I’ve heard at least one person saying to time-align a pair of dolby-enabled speakers to the path length of the reflection from the ceiling, not to the path to the listener. What concerns me is this (and this is my question): A lot of the frequencies covered by these speakers are localized by human hearing based on time of arrival of the incident wave between the two ears, and for much of this spectrum, the human brain will process two like sounds arriving just a few milliseconds out of sync, perceiving the first as “real” and the second an “echo”. How does one combat this, with speakers that depend on a reflection that is supposed to cue the audience to direction? In other words, how do you cue to height if you perceive it as an echo? Are the dispersion patterns on these speakers really so narrow, to make up for the dB differences you would have to have, I guess, to overcome the tendency to perceive the direct sound as the “real” sound and the ceiling-reflected sounds as the echo? Studies I vaguely remember suggest that at vocal frequencies, you may need the “echo” to be over 10dB louder than a sound arriving just a few milliseconds later, to overcome the perception of it being an echo of the first. So, how does one deal with this, if it is real? How do you anchor the sound to the ceiling? And if you are time-aligning to the reflection, then how do you avoid every height channel sound robbing various audience-level speakers of their perceived direction, because the Dolby speakers are firing “first” all the time, and cuing you to the front even other speakers are providing localizing information?

    1. I’m not sure from your comment if you have tried out the approach of “dolby enabled” speakers or it’s more of a theoretical question you are asking. The technology definitely works, in that you will get a sense of sound coming from the ceiling. The “height” module has a narrow enough directivity at the frequencies where humans localize sound that we don’t perceive the sound coming from the speaker…it comes from the ceiling. With a narrow directivity speaker, and where you are positioned off axis of the driver, the sound may be 6 or 9 or 12dB down at the frequencies where we are localizing sound, and so the sound coming off the ceiling is higher in amplitude even though it has further to travel. Many of these types of speakers also include a baffle that blocks the direct sound path of sound coming from the height array directly to the listener, for example look at how this Triad speaker is designed. If you are sitting with the tweeter at ear height then the upward firing drivers are obscured by the way they are recessed into the top of the cabinet. http://www.triadspeakers.com/products/dolby-atmos/ir-bronze-lr-h/

  14. I’m expanding my set-up from 5.1 to 7.1, plus adding (for now) 1 set of height speakers. A second set of height speakers will be added at a later stage.
    My question is therefore, with just one set of wide dispersion and downward-angled height speakers, where would they be most effective? Front, middle or rear?

    1. Reference the Dolby Atmos recommendations for two height speakers – they are recommended at 80 degrees from horizontal, i.e. just in front of the listening position. I’ve done a few rooms with two heights and they work well in this location.

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