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Dolby Atmos: Dispersion Requirements for Ceiling Speakers

In this blog article we look at the dispersion requirements for ceiling speakers in a Dolby Atmos system. We consider the example of a system with 4 ceiling speakers and two seating rows and show how dispersion requirements change for:

  • Speakers firing straight down vs. angled at the listening area.
  • Different ceiling heights (9’6″, 8’6″ and 7’6″).

What is speaker dispersion?

Dispersion is another word for coverage – the question we are asking is “does each member of the audience hear the same sound?”.

The sound emitted by a speaker can be thought of as a cone that expands in area as distance from the speaker increases. Simplistically speaking if listeners are within the coverage “cone” then they will hear the same thing and if they are outside it they will hear something different. It’s obviously not as simple as this, but it is true that high frequencies can fall off significantly even at small off axis angles. For example if a speaker only covers out to 30 degrees off axis then someone at 60 degrees off axis will hear something very different from someone on axis.

For a more detailed explanation of speaker coverage and the Acoustic Frontiers coverage targets please read our article on dispersion specifications and off axis response plots.

 

Dispersion requirements: straight vs. aimed

In our imaginary home theater we have two rows of ceiling speakers (a 7.1.4 system) and two seating rows. The first ceiling speaker is at an angle of 55 degrees from the perspective of the first row, and the second ceiling speaker at an angle of 115 degrees.

If you are an eagle-eyed reader then you might notice that these angles are slighly outside the official specifications. As explained in our article 10 speaker layout tips for Dolby Atmos, DTS.X and Auro, we think the specifications should be adapted for multi-row theaters, in particular to provide clear line-of-sight to all surround speakers. The impact of this are changes to the angles for the ceiling speakers, since the rear surrounds are higher than ear level.

The two drawings below show the coverage / dispersion requirements for speakers pointed straight down vs. angled at a point between the two seating rows.

With the speakers pointed straight the front Atmos ceiling speaker must have consistent coverage out to ~70 degrees off axis! If you understand typical speaker dispersion profiles then you’ll know that very few speakers have such wide coverage.

Atmos Angles Graphics_1
Required coverage / dispersion, speakers pointing straight down. 9 foot 6 inch ceiling.

Atmos Angles Graphics_2
Required coverage / dispersion, speakers aimed at point between two seating rows. 9 foot 6 inch ceiling.

Angling the speakers significantly reduces the dispersion requirements, especially for the first ceiling speaker row.

Note that these drawings only consider coverage in one dimension; in reality you also need to consider coverage across the width of the seating area.

Dispersion requirements: different ceiling heights

The dispersion requirements for the 9’6″ ceiling were shown above. Let’s now look at those for 8’6″ and 7’6″ ceilings.

First let’s see what losing a foot in room height means for coverage in the case of the speakers pointing straight down.

Atmos Angles Graphics_3
Speaker coverage, speakers pointing straight down. 8 foot 6 inch ceiling.

Atmos Angles Graphics_7
7 foot 6″ ceiling.

 

With 7’6″ ceilings and speakers pointed straight down we need almost ~80 degrees of consistent off axis coverage. Even the back row of ceiling speakers needs ~65 degrees.

Now let’s see what happens with angled speakers and lower ceilings.

Atmos Angles Graphics_4
Speaker coverage, speakers aimed at point between two seating rows. 8 foot 6 inch ceiling.

Atmos Angles Graphics_5
7 foot 6″ ceilings.

These examples clearly show that angling speakers significantly reduces the coverage requirements. The coverage of the second ceiling row will become the limiting factor in a two row home theater.

Conclusions

We can draw the following conclusions:

  1. ANY room, even those with quite high ceilings, that uses ceiling Atmos speakers firing straight down requires that those speakers have very wide coverage.
  2. Angling speakers significantly reduces the coverage requirements.
  3. As the room gets lower the coverage requirements increase.

All this goes to show that a very critical part of any home theater design is ensuring the speakers selected can provide consistent coverage of the seating area. You really can’t select a set of speakers unless you know what the coverage requirements are, and you also have to know what the speakers are capable of as many manufacturers provide no data or specifications.

The rabbit hole

Of course we have tried to keep things simple in this article but there is more complexity to consider with a Dolby Atmos speaker layout:

  • Coverage across the width of the room.
  • Differences in SPL due to some seats being closer / further away than others. This needs to be considered when the speakers are positioned.
  • Off axis suckouts. Most speakers (with exception of some coaxials) have a suckout somewhere off axis due to path length differences between the tweeter and midrange drivers. If you know where these suckouts are you can position the speakers accordingly.
  • Timbral matching. All the surrounds speakers should sound identical, and should also sound the same as the LCRs. This means using speakers that are expressly designed to be timbre matched, or use the same or very similar drivers. We’re seeing many enthusiasts use ceiling speakers from a different manufacturer to their LCRs and surrounds.

61 thoughts on “Dolby Atmos: Dispersion Requirements for Ceiling Speakers”

  1. Excellent article Nyal. Very educational. In my opinion anyone who is planning a 3D audio system must fully understand the factors you’ve explained here if they expect an optimal result. I agree with all points. The only thing I’d add is that in many cases it will be necessary to plan some compromises to some seats in order to get the ideal experience in the Main Listening Position (MLP).

    For example, let’s say that in a two row theater the MLP is going to be the center seat in the first row and that a lot of the time the second row may be unoccupied. Further let’s assume that its not possible to get the optimal dispersion for both rows. A design decision may be make it an exceptional response for the first row and “decent” response for the second row, versus a design that provides a very good response for both rows. Personally I’d rather do the former approach, especially if my second row wouldn’t be used that much.

    Keep up the great work Nyal!

    1. Agree with all your points. It’s definitely worth considering which are the seats that are really important to optimize for. Thanks for reading!

  2. I have an unusual situation…if you face the front of my theater, there is a soffit on the right that runs the length of the room. The room is ~15′ x 20 deep, and the ceiling height for the left 2/3 of the room is 9′.

    The soffit is 1′ tall/deep (from the ceiling) and 5′ wide. So, the ceiling on the right 1/3, again, facing the front of the room is 8′.

    Right now for my rear height speakers, I am using upfiring on stands. But, I think that ceiling mounted would be better all other things being equal. Or, at least rear wall mounted as rear high vs top rear.

    I am wary of a baffle effect from that soffit. Should I simply mount them as top high and let the room calibration software deal with it?

    1. Hi William

      I do not think a 1′ deep, 5′ wide soffit is something to really worry about, and you’d certainly not see much if any “boundary gain”. Depending on how close the ceiling speakers are to the soffit edge you may get some reflection / diffraction off that surface, and may want to add some acoustic treatment there.

      Nyal

  3. Nyal, thanks for the quick response.

    Would the treatment be an absorbent panel on the face of the 1′ edge of the soffit?

    Thanks again.

    Bill C.

  4. Hey this is exactly the info I was looking for. I have a room with a 15 to 25 foot high angled ceiling. I am getting a polk audio RTi setup and was gonna do A1s for the FH (gotta be on the wall cause that side of the ceiling is 25 feet up) and TM position (above couch at 15 feet). My couch setup is probably 17 feet across. Are the polks gonna be wide enough at that height or should i look into getting Mirage OMD-5s for more dispersion (and sacrifice the timbre match)? Thanks, I need help on this one!

    1. Hi Scott, thanks for your comment.

      The “correct” way to answer your question is to look at the off axis dispersion data of your Polk A1 speakers, and the angle at which the listening position is off axis to the Polks when they are installed in the ceiling. From there you can determine if the setup meets our dispersion targets. Of course that requires some “design and engineering”!

  5. Nyal, What do you think about CBT (Keele’s specific approach) to ceiling speakers in a 3d audio system? The problems you highlight seem like they might be remedied to a point by CBT, and I know that JBL now has a line of CBT speakers that could work (If someone was willing to ceiling mount such a long narrow speaker). It won’t impact the dispersion in the seating width, but there are ways to parallel the speakers next to each other, or for the daring DIY, a much more complex circular CBT array to control dispersion in all directions.

    The bigger point is, wouldn’t CBT techniques solve the seat to seat variability, the volume problem (Floyd Toole commented that it gets louder the farther away you are, making seat to seat variation much lower), and of course the dispersion problem. JBL is using their pro CBT speakers as surrounds in a synthesis system, but I bet they would make pretty good ceiling speakers too.

    Most speakers have pretty terrible response off-axis and thus make a pretty “bad” surround speaker or ceiling speaker. My personally an adherent to well done constant directivity designs (Which Keeles CBT approach includes) and use Gedlee speakers myself.

    1. Hi Matt, thanks for reading and leaving a great question!

      CBT would seem to solve a lot of issues. They have great horizontal AND vertical dispersion. The downside is their physical size (particularly length) which might make them hard to use as ceiling speakers unless your room is tall, as they would need to be directed at the seating location. We’ve had some experience of the JBL CBTs in commercial settings (we designed a sound reinforcement system for an assisted living community using them) and they worked wonderfully well.

      The issue with “constant directivity” designs (which aren’t really CD at all, as a very large part of the frequency range is not covered by the waveguide) is that dispersion is normally quite narrow and therefore it is hard to get really good coverage with them if you have multiple rows of seats and / or a low ceiling (e.g. many use 90×40 horns which means -6dB at 90 degrees off axis laterally and 40 degrees off axis vertically at 1kHz).

  6. Nyal, Great article, very informative.
    I am very confused which way to go, my current setup is Klipsch 7 (2X RF 82 II, 1X RC 62II, 4X RS 54 II) + SVS sub woofer.
    I am planning to add 4 height speakers but do not know whether i should go for in-ceiling or on ceiling or dolby atmos speakers.
    my room size is 14 wide X 17.5 length X 10 height. I have a vaulted ceiling with 3.5 ft flat roof, 6.5 ft vaulted ceiling and 5.5 ft side walls.
    My sitting position is 3 ft away from back wall. Could you please recommend what would be the best for my room?

    1. Hi Srinivas

      Thanks for reading…unfortunately a question like that requires some detailed design work, it’s not something that can be done in comments to a blog post 🙁

      1) working out what where the ceiling speakers should go based on the Atmos / DTS.X specifications
      2) then determining the coverage angle required for the speakers
      3) finally identifying a speaker that delivers the coverage requirements and is a good timbral match to the rest of your speakers

      1/2 above can be done from some basic two dimensional drawings (CAD or to scale paper drawings)…3 requires some detective work – typically firstly identifying suitable speakers and then measuring them to confirm they work

      If you need consulting assistance, feel free to get in touch!

      Nyal

  7. Nyal, very informative, thanks. So two questions: 1) What in-ceiling speakers can be aimed at the listening area? Are there any you would recommend – either specific brands or type? I know some in-ceiling speakers come with aimable tweeters, but is that enough, or does the woofer/mid-range also need to be aimed across the listening area? 2) There’s some strong enthusiasm among reviewers for using an in-ceiling speaker like the Goldenear Invisa 7000 (which I am considering), which a) can be aimed at the sweet spot and b) projects an image that appears to come from lower in the room, like a main. JBL Pro I think also make this kind of speaker. Would something like that also be an effective way to accomplish a wider soundstage?

    1. Hi, thanks for leaving a comment!

      The in ceiling speakers should be timbre matched to your mains. This ideally means from the same manufacturer AND that they have been designed with timbre matching to the other speakers in your theater. Not having timbre matching will reduce the seamlessness of the surround experience.

      The only real way to know if a certain speaker will work is to measure it. Some in ceilings have very wide dispersion, like the KEF dual concentric. Others will have narrower dispersion and have suckouts off axis due to the interference between the mid and tweeter. Knowing where these suckouts are (and if there are any) is important, as it can help you position the speakers properly (you do not want listeners to be in nulls, if at all possible).

      In the final analysis even with very wide dispersion speakers many will struggle to meet the dispersion requirements without angling them in. It’s mostly the tweeter that needs to be angled, and smaller tweeters will have wider dispersion than larger tweeters simply due to the laws of physics.

      The optimum is to use the same speaker in all surround locations. This might mean a box speaker on an angled ceiling mount directed at the seating area.

  8. This is the first time that I’ve seen someone put the “rear” set of Atmos speakers between the first and second row…

    I have been wondering about this for a while since every other diagram is for 1 row of seats only.

    If we primarily use our front row, but about 25% of the time have someone in the back row, would this be ideal, or should we look for making the “box” of 4 ceiling speakers around both rows like other mentioned at CEDIA 2014 and 2015?

    1. The Atmos drawings provided by Dolby are too simplistic, as they represent only one seating row.

      Industry convention is to lay out the speakers based on the main listening position, which typically means the 2nd row goes between the two rows of seats. We will, room dependent, sometimes add a third ceiling row and adjust the angles of all three ceiling rows to provide even coverage.

      Our approach is in line with what is being practiced by other designers and what CEDIA will be releasing in their upcoming spatial audio layout white paper.

      1. Cool. It just seems odd after about 1.5 years of the “Atmos Box” to see things like this. Not saying it is wrong, it just looks different. I am just about 2 weeks away from installing “on-ceiling” speakers in my own theater, so this updated information is timely.

        With the idea that it is important to angle the speakers towards the listening area, the front ceiling speakers make complete sense. It was the 2nd set pointed away from the front row that threw me for a loop in rooms with lower ceilings, but with even reasonable dispersion, the front row should be covered nicely.

        Thanks Nyal.

        1. CEDIA’s forthcoming recommended speaker layouts for immersive audio which was created by a working group of top theater designers, manufacturers and integrators does not implement either the “Atmos Box” or “surrounds at ear height”…you’ll also find that Dolby at the moment do not produce any layout guidance for multi-row, tiered seating home theaters.

          The 2nd row were pointed away from the 1st row to provide better coverage to both rows. It looks funky until you think about the engineering reasons why it is done.

  9. Excellent article Nyal. Angling the speakers to optimise their dispersion makes a lot of sense.

    I was thinking of buying ceiling speakers that allow me to angle the tweeters rather than the whole speaker. Would this work? Speakers with pivoting tweeters seem to need less depth for the ceiling cut-out than those which rotate the entire speaker. Also, am I correct in assuming that I do not need to also angle the bass drivers since bass is non-directional?

    Many thanks for all the great advice
    Ion

    1. You are right, generally it’s the tweeter that becomes directional and so this is the main part of the speaker that benefits from being angled. There are speakers on the market with “aimable” tweeters which could work well depending on how far off axis the listeners are. Beware though, some speakers marketed with “aimable” tweeters only have maybe 10-15 degree of adjustment, which is not really enough to deal with the requirements for the front ceiling row.

      With all speakers there is also the risk of off axis suckouts due to crossover related interference between the mid and tweeter. The ONLY way to know if your speaker has these issues and where they are is to measure them or to have the manufacturer provide off axis data in both the lateral and vertical planes.

      Generally you do not need to angle the bass driver, but if it is a mid-woofer with a high crossover frequency to a tweeter you may get a suckout develop at high off axis angles (say above 60 degrees) due to the mid-woofer becoming directional.

  10. Is someone was to use an overhead speaker in a “traditional” bookshelf configuration (1 tweeter over 1 woofer), how should that be angled? Tweeter “down” further than the woofer, or angled on its “side” so both are equally angled, or doesn’t it matter?

    Tweeter down would basically make it like an inverted bookshelf, but also be hanging down from the ceiling further than a “side” angle which would be, obviously, like a bookshelf on its side (tweeter next to the woofer instead of above it), but wouldn’t hang down as far since it would be hanging from its long edge and not short edge of the speaker.

    1. Ideally you need to have the measured off axis dispersion data so you can see where any crossover related suckouts are located and then use this information to position the speaker appropriately.

      Normally a vertically stacked driver configuration (tweeter over mid-woofer) has wide horizontal dispersion and narrrower vertical dispersion, and there are often suckouts in the vertical plane.

  11. I’ve been struggling with my Height Vs. ceiling set up. I’ve tried several different configurations and not getting what I want from Atmos or dolby. I’m running a 9.2 channel denon receiver with 2 external stereo parasound amps for a 13.2 channel system. The room is small but currently running front, Front wides ( hardly used) Surround, surround rears and here’s the issues,I’ve got 4 more speakers mounted in the front height and rear height positions but they are on swivel brackets and can be angled to the LP ( listener positions)I’ve programed as heights and just don’t get much out of them. I program them as dolby overheads and still don’t get immersed. I’ve tried front heights and rear overheads and still not diggin it. whats the best way to acheive atmos? programing as heights or overheads in a small room . all the satellite speakers are bose 161 . B&W centers and fronts. any help or experience would be appreciated

    1. Thanks for your comments. It’s hard to say exactly what the issue is with your particular setup, because if it’s done right you should feel like you are in a “bubble of sound”. Some items to consider:
      1) are all the speakers in the right place?
      2) are all the speakers timbre matched? Clearly not if you are using B&W LCR and Bose elsewhere…
      3) is the system properly calibrated? Speakers level matched, time aligned, etc.

      1. Thanks for the reply
        1.) Well, not exactly but close. The speakers are in the right place but not all at the right since I couldn’t have die poles all around. I did however point them all in the right direction. I’m no only 7′ from the sl and rl and 9-10′ from the fronts.
        2.) The fronts are bookshelves and certainly are more capable below 80hz but I the fronts fit in nicely to the ear. matched enough to the point that I really can’t tell where the bass is coming from and I think that’s good?
        3.) Fully calibrated by audyssey and then tweaked by ear after. I’m very experienced with Live band PA sound engineering so I get it . But, working with 30,000 watts in an arena is not the same as home audio like this. Its like the difference between cooking and baking 🙂
        My real question is whats better? Programing front high and rear high? Front overhead and rear overhead, front high and rear overhead or rear high and front overheard. will Atmos, DTSx or Dolby/ Plus utilize them the same or will I lose effects with high programed vs overhead. Whats the most efficient way to get the best out of the 12 surrounds. there are many options Atmos- 7.2.4, 13.2, My receiver is a denon avrX5200W

        1. sorry about the typing on my reply, I hope you get the jist.. and remember, in addition the receiver I have 2 parasound 2125 stereo amps currently connected to the front and rear high pre’s

  12. Just wondering if ceiling speakers are selected for Atmos height speakers and they are angled at 15 degrees in their housing then how far forward of the first seating position should they be placed. I mean for the 7 foot 6 inch room that matches my space almost exactly. I don’t have dispersion specs from speaker manufacture, but I’m looking at New Wave Audio C-890K’s.

    1. Hi Jon, thanks for reading and leaving a comment. I’m sorry to say that the only way to really know is to do a little trigonometry…and with respect to the ceiling speaker dispersion if you cannot measure a physical sample then you’ll have to make some assumptions. I think assuming decent off axis to 45 degrees off axis with those speakers (not necessarily all in ceilings, as it depends on how they are designed) is safe…beyond that you would need to measure.

  13. I have a new question. Going with the 2 pairs of overheads like your diagrams (specifically for me, I am closer to the 7’6″ height than the other options). What do you set the sound processor to for those speakers? Overhead fronts/overhead rears, overhead fronts/overhead middles, something else? Again, understanding that the goal is best sound for the front row and still good sound for the 2nd row.

    Thanks.

    1. The best setting would likely vary depending on how the manufacturer has implemented it…so some experimentation is in order!

  14. Great write up. Not sure if you have any experience with the Revel 763L in ceiling which has an angled baffle. Seems like it would make sense to use based on this article.

    1. Well requirement #1 is timbre matching of all speakers. The Revel you refer to is a specific in ceiling speaker, I’m not sure what other speakers it is timbre matched to?

      But yes, angled baffle speakers (where the tweeter is angled) make A LOT of sense for the ceiling speakers in an Atmos or DTS.X or Auro setup.

      1. Thanks Nyal. I agree with your point of timbre match. I’ve heard them paired with other Revel speakers as well as some JBL speakers from the Synthesis line (M2) seem to be a nice match. Probably by design since they all fall under Harman.

        1. I’d be surprised if the Revel you referred to is a good timbre match to the horn speakers, due to totally different drivers and dispersion patterns…

  15. I noticed that the atmos back pair of speakers were situated between the first and second rows and were toed in towards the second row. Is that conventional or are the back pair farther back and toed in towards the MLP? My setup is virtually a carbon copy except for the ceilings being closer to 10ft and the speakers being in ceiling. Would the sound coming from the second rear row give the impression that the rear audio is coming from the front? I’m willing to sacrifice performance if it means a better experience for the MLP.

    Thank you!

    1. Always lay out the surround speakers with respect to the MLP! In this particular theater that means the 2nd row of ceiling speakers ends up between the two seating rows. The speakers are toed in towards the 2nd row because that provides the best coverage of the two rows.

      1. Would that give the impression that all the audio is coming from the front for the second row?

        Would it be better to have the second row of speakers slightly behind the second row?

        1. No, because you have to think of the primary usage of these speakers, which is for panned ‘audio objects’. The really important thing is to maintain proper spacing and angling of the ceiling speakers from the LCRs and rear surrounds. In most theaters if you put the rear ceiling speakers behind the second row of seats then they would be too close (in an angular sense) to the rear surrounds.

  16. Hi Nyal, love your site great resource for audio, as atmos has been in the wild for a while now are elevation speakers placed high or at the apex of where the wall meets the ceiling considered a compromise to direct overhead in ceiling speakers?
    I will be running a full klipsch thx ultra 2 set and possibly looking to use the klipsch rp atmos angled baffled speaker.
    The theatre is currently under construction, elevation speakers are certainly easier to accommodate rather than in ceiling but i wouldnt want compromise.
    Thanks for any advice.

    1. Yes, it’s a compromise to put “Atmos” speakers on the wall as there is insufficient angular separation between surrounds and Atmos speakers. Minimum recommended separation between the surrounds and Atmos speakers is 30 degrees.

  17. I had a question I have one listening position only. Room is 21×18 ceiling speakers will be mounted at 11 feet 4 of them. Would the definitive technology uiw rss II be a good speaker. At 1600 for 4 I want to make sure. All my speakers are definitive 6 bpvx surrounds side, back, and front wides. CLR3000 Center and bp7001 mains.

    1. Hi Joel

      Thanks for reading! I can’t answer for sure, and only refer you to what’s discussed in the article…check your angles relative to each seat, check your speaker off axis dispersion patterns (measure them if necessary) and base the speaker positions on that…aiming to get all seats in a part of the speaker’s dispersion that will hit -3dB @ 4kHz.

  18. Great article. I’m just in the final stages of construction of a basement home theater as per the Volkmann home theater ratios (Volkmann 1.0 : 1.5 : 2.5), one row of seating, with the option to add a second row at a future time. The ceiling height is very low at 7’3″ since it’s a 70 year old home. I’ve just changed gears from Dolby 7.1 to try and set this up as Dolby Atmos 5.1.4 and add the wiring needed, etc. and my concern is that the ceiling is very low.

    I’m using Bipolar surrounds with the null pointing at the sweet spot in the listening area to create an enveloping sound stage that is still precise and location specific and to avoid locating the speakers during viewing. My question:

    Do you have any experience using Bipolar surrounds with low ceilings?

    I’ve read from Dolby sources that Bipolar surround speakers (but NOT Dipole) can be very effective in a Dolby Atmos setup. I’m considering embedding the speaker enclosure into the ceiling through a hole in the ceiling drywall and angling the null in the center of the Bipolar speaker towards the listening area as in your diagrams above to give a wider coverage, without the negative impact of the ceiling speakers being closer to the listener than all the other channels. I realize Atmos should be a “point” source of sound, but I’m aiming for a “sweet listening area” rather than one “sweet spot” to maximize listening effect for all positions in the home theater.

    Thanks for any input.

    1. I think you are confusing Bipole and Dipole. Bipoles have no on-axis null, Dipoles DO. You do not want to use Dipoles for spatial audio. The main reason is that Dipoles are very poor at surround localization, they are intended more to provide spaciousness and avoid localization. You want localization with Atmos and DTS.X! That’s the whole point of it! Bipoles can work well in small rooms and low ceilings, since they have very wide dispersion.

    1. Not to my knowledge…I’m not sure what the hold up is! Though we attended the training session 1.5 years ago and have been working to the recommendations since.

    1. #1 advice is to ensure proper coverage of the seating area (so position speakers correctly and ensure the speakers have sufficient dispersion for proper coverage of the seating area). #2 advice is to timbre match them to the other surrounds, so that if a sound pans from say left surround to overhead the sound “signature” does not change.

  19. Hi Nyal,

    I am building an Atmos system and I need some advice on my center speaker please.

    Some say that the typical horizontal woofer/tweeter/woofer center speaker design is a flawed concept (see reference #1 and #2 below).

    Reference #2 claims that 3 identical vertical floorstanding speakers (Left, Center, and Right) is the best configuration.

    I do not have space below my TV for a vertical floorstanding speaker.

    Question: Would I be better off with a typical center channel speaker, or with a floorstanding speaker identical to my L and R speakers that I lay horizontally, i.e., L and R speaker vertical, and center horizontal?

    Thank you!

    Jacob.

    References:
    1. https://www.cnet.com/news/attention-home-theater-shoppers-think-twice-before-buying-a-center-channel-speaker/
    2. http://forum.blu-ray.com/showthread.php?t=89614

    1. 1. the MTM design is generally a flawed concept due to off axis comb filtering between the two mid-woofers. However there are a number of center channels that ARE properly designed and will not have off axis comb filtering…for example all the KEFs (due to the concentric tweeter / midrange), Revels from the Performa 3 series up, etc.

      2. agree that the best approach is a timbre matched set of LCRs. They do not need to be floorstanders. I’m not sure what floorstanders you have but you might consider selling and purchasing a matched LCR set if there isn’t a good matching center for your floorstander L/R. I would not do a floorstander on it’s side as that will have the same issues as a MTM design.

  20. Hi Nyal,

    Thanks for your thorough write up. I’m trying to figure out optimal ceiling placement for my selected speakers.

    I’m going with Polk Atrium 5’s as they are 1. light, 2. have similar sensitivity and FR to my Polk RtiA speaker setup (7 of them at ear level) and are from the same manufacturer 4. remain close to the ceiling as it’s only 8 feet tall and 4. can rotate on their axis to be angled directly at the couch. (I’m just hoping for a similar timbre match between them – they’re the best compromise I can come up with).

    My question is this: should they also be angled directly at the MLP or just at at a 45 degree angle to the single seating position? I’ve drawn something up here: http://imgur.com/Jiw5SDF

    So you can see the front two ceiling speakers can be angled at 45 degrees and pointed towards the couch, or 45 degrees and pointed directly at the MLP (the purple mark). Which do you think is the best way to go?

    Thanks!

  21. Hi,
    This is an informative article. I am setting up a new family room that is 16×20, seating facing long wall. The ceiling is 8′ where the LCRs and TV will be and slopes up to 12′ (2.875:12 slope) in the rear. An existing room with 7.5′ ceilings (13×19) opens up in the rear of the new room. In essence, I don’t have much of a back wall.

    In considering a new 7.2.4 set-up with existing Polk LSi speakers (for an earlier 7.1 set-up), I am considering 700-LS ceiling speakers for the ceiling. However, the slope of the ceiling concerns me.

    Considering the the dispersion characteristics, should the ceiling speaker shift frontward a bit to mimic the angle to seating if it were a flat ceiling? For example, extrapolate the front row angle to the ceiling speakers to an imposed slope above your example drawing?

    Our primary seating is roughly in the middle of the room, no more than 8′ from the front wall. Or, am I just doomed?

    1. The angle of the ceiling should not make any difference with respect to Atmos speaker placement. For the front Atmos row it should improve things, as the tweeter will be pointed better at the listening area. For the rear Atmos it will make things worse, as the speakers will point at back wall. Not sure there’s much you can do about this, short of using speakers with an angled baffle.

  22. I’m currently planning an upgrade to my audio 5.1 system. Planned improvements will be getting an Atmos and DTS-X capable receiver (another Marantz) to run in my 11-by-18 foot media room which has a cathedral ceiling that peaks at 13 feet in the center. Since my front stage is a set of floorstanding B&Ws with a B&W center — and all drivers running Kevlar speakers — I would guess that the best matching timbre would be to use a set of B&W Kevlar speakers wall mounted high in the rear and aimed down into the listening position. My question centers on what are the expected sound characteristics expected to be sent to those height speakers? Would the normal Atmos and DTS-X effects require better three-way speakers or is it more likely that the sounds conveyed might be less broad-range and perhaps more likely upper register in character? I guess I’m trying to justify spending less on those special effects speakers if the normal effects are somewhat constrained or muted as a matter of course. Does this question make sense?

    1. Good call on using B&W speakers for the Atmos ones as they should match timbrally.

      In terms of which model to use, ideally you would have the same speaker in all surround locations (sides, rears, ceiling). I’m hearing some pretty full range effects sent to the Atmos speakers, and I can only imagine sound mixers will continue to use them more aggressively as time goes on.

      One consideration is that the ceiling speakers are often closer than the surrounds and rears (though may not be in your room due to the high ceilings), so you can sometimes use a speaker with lower output capability (e.g. a 4″ driver vs. a 6.5″).

      You also need to consider placement, and in particular the angles relative to the main listening position. It won’t matter if the timbre matching is perfect if you don’t have sufficient angular separation to the sides and rears for the Atmos effects to be localized as the director intended.

  23. Excellent articles and information! Thank you… Its appreciated!
    I have a 5.1 Onkyo set up currently. I am going to a 5.1.4 system and am in the process of searching for a new receiver and 4 ceiling speakers. Regretfully I have what I believe is a terrible problem with my AV room. The couch is backed up against the back wall. Consequently my rear surround speakers are currently hanging on the back wall close to the ceiling, All speakers are Paradigm book shelf types. The 4 Atmos in ceiling installed speakers will be 6.5 or 8″ round cone 15 degree offset Polk type of speakers unless you tell me they won’t work properly. The room is 17′ 8″ front to back by 16′ 6″ wide. 9′ ceiling height. The brand new 65″ SAMSUNG 8 series 4k is built into an entertainment cabinet as are the front and center speakers. Finally the 18″ Sub-woofer sits on the floor in front of the entertainment cabinet. So my biggest dilemmas are the rear surrounds being positioned right behind the couch and WHERE SHOULD I installed the 4 ceiling speakers? Any helpful ideas will be very much appreciated! I can’t wait to watch and listen to my 1st 4k atmos movie!
    Regards,
    Jerry

    1. You may want to consider just having two top speakers, as you will likely not get much benefit from going to four with your rears positioned where they are. Normally with two you’d put them slightly in front of the seating position, maybe at 70-80 degrees when viewed side on. With four you’d put two of them behind you, which is likely where your rears are.

      Theoretically you can benefit from adding speakers up to about 15 degrees angular separation between each one, but I think 5.1.2 is probably a good balance for you.

  24. Good evening…
    Please let me know about how long it takes to get a response the the above query I sent in 11/17.
    I’m really looking forward to getting my system going.
    Thanks!
    Jerry Slonsky

  25. Oooooops… I see that the response actually did show up. It must have been seconds ago.
    However I’m really disappointed about using only 2 speakers. What would you think about it if I move the rears that are close to the ceiling down by putting them on stands so I can take the advantage of having four Atmos speakers in the ceiling. I keep reading that 4 is far superior to have only 2. If you think that would be workable how high off the floor should they be? Maybe a foot or two above our heads? (assuming my wife will let me) I could also mount them on the wall instead of the pedestals. If you think 2 ceiling Atmos’ is the best and only way to go I can buy a much less expensiveness Onkyo receiver since I won’t need the 9.2 version. I believe I can use a 7.2 version instead. If you will allow me one more question, do you think my old 73 year old ears will be able to tell the difference between a 24 vs 32-bit DACS on on the receivers channels?

    Thank you again for you terrific help. HAPPY THANKSGIVING to you and yours!!!
    Jerry Slonsky

  26. Please explain what “YOUR COMMENT IS AWAITING MODERATION”. Does that
    mean you are waiting for something from me?
    Thank you Nyla!
    Wishing you and yours a Happy Thanksgiving!
    Jerry Slonsky

  27. Weird! For some reason the only response I received on the above questions I had has dropped off and for some reason I can no longer see it.

    Am I no longer a member of the group? Looking forward to you reply.
    Thank you and Happy Thanksgiving to you and your loved ones!
    Jerry Slonsky

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