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Home theater speaker layout – 5.1 and 7.1 recommendations from Dolby, THX and ITU

Where do I put all these speakers in my 5.1 or 7.1 channel home theater? That’s the question we tackle in this article.

There are three main organizations that provide guidance on speaker placement. They are THX, Dolby and the International Telecommunications Union (ITU). THX and Dolby guidance is directed principally for movie production and reproduction whilst the ITU recommendations are targeted primarily at music.

Left, center and right

  • Angular separation of left and right speakers between 44 and 60 degrees. THX recommends 45, Dolby 44-60 and the ITU 60. We recommend 45 degrees or slightly wider, tucking the left and right speakers inside the edges of an acoustically transparent screen. This gives best tracking of onscreen action to audio. Placement of speakers significantly outside the screen boundaries can sometimes result in a disconnect between sound and screen.

Two surround speakers

  • Angular separation of 110-120 degrees. The Dolby and THX recommendations are 90-110. We prefer a slightly wider separation in line with the ITU that allows for rearward localizations when required.

Four surround speakers

  • Angular separation of 60-100 degrees for sides and 135-150 for rears. Dolby and THX recommendations are 90-110 for the side surround speakers. Dolby recommend the rears be placed at 135-150 degrees whereas THX recommend both speakers be placed together on the back wall. We prefer the front pair to be level or slightly in front of the main listening position and the rear pair to be at around 135 degrees as Floyd Toole recommends in his book Sound Reproduction.

15 thoughts on “Home theater speaker layout – 5.1 and 7.1 recommendations from Dolby, THX and ITU”

  1. Just reading your blog about speaker angles. I just picked up a lazer level on a tripod to gauge what distances I’ve got mine set at, and it seems my side surrounds are closer to 90 degrees from the LP then I thought … I’ve got a 7.1 set up, so my assumption is that having them at 110 would be more beneficial in a 5.1 set up, as you’d like to get more atmosphere from behind, where as in a 7.1 where you’ve got two rears already, it’s not as important. In addition, wouldn’t room correction software such as Audyssey XT32 balance things out? –
    I see that you’ve stated your preference for fronts to be at an angular separation of 45 to 60 degrees. According to Dolby recommendations they should be at 30 degrees to either side of the LP .. though mine are closer to 40 degrees 1. Am I misreading you recommendation and 2. Will a 10 degree variation ( 40 from the LP to either side ) account for much sonic change? Cheers!

    1. Hi Sean good question!

      You are right on that in a 7 channel system you have more flexibility with placement of the side surround speakers. In fact you can have them at an angular range anywhere from 60 degrees off center line to 110 degrees. Putting them forward of the listening position (angles below 90 degrees) increases forward envelopment. Personally I think 60 degrees is maybe a touch too far forward but certainly 70-80 degrees I like and think works great.

      With fronts for home theater ideally you should position the left and right so they tie back to what is happening on the screen. Some sources think you should have no more than 3 degree difference between the screen edge and the position of the left or right speaker. This puts the left and right either slightly inside or slightly outside the screen edge.

      By angular separation of 45-60 degrees I mean 45 to 60 degrees between the left and right speaker. Measured off the center line that equates to 22.5 to 30 degrees. If you have an 80 degree separation between left and right then personally I think that is too wide.

      Thanks and hope that helps!

      Nyal

      1. Hi.
        I the max 3 degree difference between the screen edge and the position of the left or right speaker very tight condition?
        In my room (speakers behind the AT 2.35:1 Seymores creen) this difference is about 5 degree on each side.
        I have total 40 degrees angle measured between acoustic axies LR, viewing angle total is 50 degrees. It is because in left corner I have the chimney in the room – about 26 inch width – and cannot put the the L speaker wider in the left to the screen edge.
        I could move the screen about 9 inch in the right and then move the center speaker and right speaker accordingly to have the LR wider but in that case tha LCR speakers would not be fully in symmetry to the rectangular room. The surrounds would be not in symetry to the front speakers too as the THX recommends.
        The speakers are XTZ Cinema Series. Joel from XTZ told that M6 need to be 50-60 degrees in total, 25-30 on each side for better sounstage. 60 is outside the screen in HD signal even with 2.35:1 screen. 50 degree is on the edge screen.
        What do you think could I stay with 40 dregee angle for speakers by 50 degree view angle?
        regards
        Andrzej

        1. Hi Andrzej and thanks for reading. Yes, as you have found out it is very difficult to meet every single ideal in terms of home theater layout. Personally if you have a 5 degree difference I would not worry. As for the XTZ recommendation, you can do that, but as I said in this article, you should try and keep the L/R as close to screen edge as possible for best tracking of on screen action to audio.

          1. Hi.
            Thank you for you time and help.
            I heard a lot of pros about baffle wall for home cinema audio instalations.
            I have the xtz M6 cinema series speakers. for fronts LRC. They are relativly compact and light only 8 inch depth
            As they can be mounted stright on wall, I still hesitate if
            1. To bulid baffle wall for them (a little complicated task)
            or
            2. To hang them on back wall with acoustic treatment around them and finishing with black material on all back wall, and after that to build construction for the screen.

            The second solutions is a lot easer to make.
            What do you think, is it worth to build baffle wall, which has to be made really solid for such speakers as M6 Cinema XTZ speakers?
            I would very appreciate your sugestion.
            regards
            Andrzej

  2. What height do you place your surrounds? ITU seems to be on line with ear height or up to 15 degrees with the speakers pointing down toward the listening position, THX says 2 feet, and Dolby is vague and states just above ear level. You have some great information on here. Thanks for your time.

    1. Hi John

      The answer as usual is ‘it depends’ πŸ™‚

      With home theater the surrounds play back a mostly decorrelated soundtrack designed to add spaciousness. However they do also play back discrete effects.

      If you have a row of seats and the surround speaker level with the seats or behind the seats then you can easily get speaker shading either from people’s heads or seat backs. This is the reason you typically see recommendations to raise surround speakers above ear level. It’s so you can trace a clear line from your ear to the surround speaker.

      You also have to be aware of the speaker design. Most speakers have vertically oriented midrange / tweeter arrays (tweeter above midrange) and these always have some dip in output around the crossover at a certain vertical angle. The vertical angle where the dip is varies from speaker to speaker. The dip is caused by the different path lengths of the sound from the midrange and tweeter drivers. Some speakers (such as Procella Audio speakers) are designed with the intent that they may be placed above ears and so can work well at vertical off axis angles up to 30 degrees or more. Other speakers are not designed with this usage in mind and so will have noticeable nulls at as little as 10 degrees off axis.

      Hope that helps!

      Nyal

  3. Hi Nyal Mellor. Thanks for sharing your wisdom πŸ™‚ I have my listening position close to the rear wall. Is 5.1 or 7.1 the best for me? I have on-wall rear speakers, and am thinking of also getting in-ceiling.

    1. Generally speaking with listening positions within a couple of ft of the rear wall I will go with angled ceiling mounted surround speakers in a 5.1 setup. The surrounds will be level or even slightly in front of the couch. I will often put diffusers at the top of the wall behind the couch to direct some of the back wall reflection from the surround speakers down to the couch.

      The only situation I might use 7.1 is if the couch area to be covered is very large and the couch is placed 3-4ft from the back wall. In which case I would use speakers on the back wall but would be very careful about choosing them because they are going to be listened to at all kinds of extreme off axis positions. Coaxial speakers work well in this situation I have found.

  4. Thanks Nyal. The second part of my question is, once placed 110 degrees behind the reference position and 10 degrees above ear level, would I aim the speakers directly toward the reference listening position? Or, would I have the speakers face each other? This is for a pair of Andrew Jones 2nd generation bookshelves. Thanks again.

    1. Hi John

      If only one row, then aim them towards the listening position. If two rows you need to strike a balance. If you position the speaker so that it is not firing directly at you what you are aiming for is that the speaker is positioned within its operating window (where the frequency response closely resembles the on axis sound).

      Thanks,

      Nyal

  5. Nyal,

    I’m enjoying reading all your blog articles. Learning a ton of information. I immensely appreciate you taking the time to do all this.

    I have a few questions please sir.

    When building a THX based speakers system for Dolby Atmos (future DTS-UHD) (9.2.4) system:

    * If there will be two rows of seats, should the side surround THX dipole speakers go between the two rows on the side walls or some other location along the side walls?
    * Should the rear (back wall) THX speakers be dipoles or direct radiators? And why?
    * Should the ceiling mounted THX speakers be dipoles or direct radiators?
    * If using two THX subwoofers, which is best – both up front or one in front of room and one in back of room?

    [If additional information is needed to assist you in your responses: 15’6″W x 26’8″‘L x 10’H room dimensions. No seating is at any wall, specifically not against the back. Room acoustical treatment planned.]

    THANK YOU sir in advance for your guidance.

    1. Hi Joey

      Thanks for reading and I’m glad the articles are useful.

      First off, I would not use dipoles for anything. The whole dipole theory has been discredited recently by the work of people like Floyd Toole. His very good book called Sound Reproduction, has a nice summary of the history of dipoles and their issues. Essentially dipoles were created back in the dawn of surround sound when there was only a single surround channel as a way to provide a decorrelated surround field. Once we had discrete 5 channel surround recordings there really was no need to have dipoles for surround. A dipole is two drivers driven out of phase with each other, typically one points forward and the other backwards. The main issue is that dipoles work by providing a cancellation of sound energy between the two drivers and the theory goes that you put this cancellation null in line with your seating rows hence reducing the localization of surround sound information. This works fine if your surround tracks only have decorrelated sound in them for the purpose of adding spaciousness (the feeling of being in an actual place rather than just listening to a recording). However it does not work well for surround tracks that have any localized sound effects such as off screen doors closing, footsteps, gunfire, etc. The fundamental problem is that cancellation timbrally distorts the surround field information. If you look at a frequency response chart of a dipole on axis it will have a huge suckout between 1 and 2kHz, and maybe wider depending on the driver. Much better alternatives are wide dispersion monopoles or bipoles. With object based audio like Atmos there will be audio objects panned around the room between the different speakers. You need to be able to localize the sound oject as it moves around for this to work. I therefore think is it very critical that all speakers are timbre matched (i.e they sound the same) for this to work properly. Dipoles surrounds don’t sound like monopole LCRs, and therefore the whole thing is doomed to failure from the start. So in conclusion…you should use monopole or bipoles for the surrounds. Very few manufacturers have timbre matched solutions for Atmos, Auro and the like. Procella is one, KEF is another (their new CI series, such as the Ci3160RL-THX).

      As for subwoofers, that is a whole other story. If you have two rows of seats the rule of thumb is that you actually need FOUR subwoofers to provide consistent seat to seat bass response. Check out this multiple subwoofer article and this one on seating layout.

      Even if you put together the design yourself we have a home theater design review service that basically makes sure your design is optimized and you haven’t made any mistakes. If you are interested, please get in touch.

      Nyal

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