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Home Theater Speaker Placement
Jon Herron, Trinnov Audio, explains best practices on home theater speakers, avoiding mistakes for the best sound.
Article by Jon Herron, Trinnov Audio
So, you want to design a home theater that will do justice to audio formats like Dolby Atmos®, DTS:X® Pro, and Auro-3D®. Exciting experiences await you with all of these immersive audio technologies.
But where do you start?
These companies support far more than the usual 5.1 or 7.1 channels in home theaters. But they all have different ideas about where to locate the speakers beyond the “normal” 7.1.
At Trinnov Audio, we have been supporting these high-channel-count systems longer than any company in the world. We have rendered all of the 34.1 channels of Dolby Atmos since 2015 – something that no other company can do, even in 2023.
As a result, we have more experience helping our customers design these immersive audio systems than anyone else. We have long since climbed the learning curve and are happy to share some of our experience and understanding with you for Kaleidescape's Home Theater Guide.
Speaker Placement for High-Performance Home Theaters
In this article, we will focus on simple and logical rules of thumb regarding how many speakers you want (or need) in your theater and where you should place them.
For a more comprehensive look at the design of high-performance, multi-format, multi-listener home theaters, please read our 19-page Loudspeaker Position Guide. This article will just hit the highlights – you can decide to go deeper into the subject after reviewing what’s here.
For this article, we make the following basic assumptions:
1. You share your TV room with others at least some of the time and would like everyone watching to have a similar experience.
2. You would like the luxury of watching a movie and having its soundtrack reproduced correctly without squinting at the fine print to see what format the film uses.
Assuming we can agree on this much, let’s move on to the most straightforward considerations.
How Big Is Your Theater?
One of the most common mistakes is under-specifying the subwoofers in large rooms. There are several goals achieved by having multiple subs in the room:
- more output, of course;
- but, with intelligent placement, you can also achieve smoother, more consistent seat-to-seat results, enhancing the first goal listed above;
- ideally, you enjoy not only clean, accurate bass but also deep, impactful bass that you feel as much as hear
In larger rooms, you must move a lot of air to hear and feel it. As a result, you usually need some combination of more and larger subs.
Think of all the air contained in your room. One or two 12” subwoofers cannot move enough air to create a genuinely concussive experience. The amount of “woof” you need is a function of the room’s volume, which grows rather dramatically when you consider the higher ceilings required by tiered seating.
Some companies even design and build “infrasonic subs” that reproduce frequencies so low that you don’t hear them so much as feel them. They pressurize the room when there are extremely low frequencies in the soundtrack. The added realism is striking. It makes what seems like a direct, physical connection to your emotions.
These infra subs complement more conventional subwoofers to create a haptic experience for everyone in the room. Trust me: I once heard AVS Forum’s Home Theater of the Decade—The Hahn Theater—which uses a dozen custom-made 24” infrasonic woofers. The experience was both palpable and unforgettable. (On a related note, Kaleidescape recently launched its Filmmaker Spotlight series, and coincidentally, they feature none other than Rob Hahn—the owner of that memorable home theater.)
How Big Is Your Picture?
The next question concerns how many screen channels you require. What angle is subtended by the edges of the screen as seen from your favorite seat?
In this, the actual size of the screen is less important than the viewing angle. With anything under about 60° (an equilateral triangle), you are probably okay with three screen channels (Left, Center, and Right). After all, high-performance stereo systems image beautifully with just two speakers in that arrangement with the listener.
However, in a theater setting, you will likely have people seated off to one side or the other, not in the “sweet spot.” This explains why theaters have a Center channel to stabilize the image for off-center people.
Both Dolby Atmos and DTS:X Pro can support more screen channels, as many as five or even seven. These additional screen channels can fill the gaps between Left and Center and between Center and Right, creating seamless pans across the screen. But they are more valuable when sitting in the front rows of a crowded commercial movie theater than in most home environments.
How Many Rows of Seats Are in Your Theater?
Now we get to what many people find the most confusing. We have an entire article just on this subject. But a fundamental tenet of good home cinema design is the relationship between the overall room and the portion of the space dedicated to the seating area.
Let’s look at some practical examples.
The Single Listener
Some people live alone and enjoy music and movies. If that is your situation, you may find that a simple system with five ear-level speakers and four ceiling speakers does the trick for you:
When carefully calibrated, the lucky person in the Main Listening Position (MLP) can experience sound coming from around and above him with relatively smooth pans both forward to back and side to side.
This essential “five lower, four upper” speaker system depends heavily on phantom imaging to fill the spaces between the actual speakers. If you move out of the “sweet spot,” things will not work nearly as well. For this reason, this system is best suited for a single listener.
A Small Theater: A Single Row of Listeners
A significant step up in immersion and spatial resolution for a single row of listeners would be a “nine lower, four upper” speaker arrangement like this one:
This system adds both Rear Surrounds and Wide channels. The Wides fill the large gap between the screen and the front-most pair of side surround speakers. Even a single listener will enjoy the benefits of adding Wide channels approximately halfway between the outer screen channels and the side surrounds you would find in a basic 7.1 system.
Although this system is somewhat focused on the Dolby Atmos approach to speaker placement, it can deliver good DTS:X and Auro-3D reproduction with Trinnov’s unique Remapping technology.
For a more flexible speaker arrangement that does a better job of reproducing all three immersive audio formats, one can add another pair of speakers above the listeners:
The addition of the Center Height and the Overhead/Top/”Voice of God” speakers explicitly support both Auro-3D and DTS:X Pro, lending some height to the front sonic stage as well as directly overhead. (With the Altitude platform, taking advantage of these additional speakers is incredibly easy and automatic. You do not have to do anything beyond playing the movie you have selected for the evening’s entertainment.)
Mid-sized Theater: Two Rows of Seats Means Two Pairs of Side Surrounds
Many home theaters have two rows of seats to accommodate friends and family better.
As the listening area becomes a larger portion of the room itself, more and more people may be sitting in less-than-ideal locations (in the corners, away from the MLP). As such, you need more speakers to anchor the sounds where they belong in the room so that people do not have to rely as heavily on phantom imaging to fill in the gaps between speakers. Having these extra speakers ensures that everyone has a much more similar perception of the soundtrack and the movie itself.
Specifically, it makes sense to have a pair of side surround speakers for each row of seating. It serves the purpose of everyone having a similar experience of the movie soundtrack.
But what will those speakers be playing? This is where it gets interesting.
Using Dolby’s terminology for these examples, the Ls/Rs speakers (the primary left and right side surround speakers) should be approximately even with the Main Listening Position (MLP). These speakers will reproduce audio objects that are 90° away from the Center channel that is directly in front of the audience.
If the “other” row of seating is in front of the one that includes the MLP, its surround speakers should be what is called “Ls1/Rs1.”
If the “other” row of seats is behind the MLP, the Ls2/Rs2 channels should be assigned to its pair of surrounds.
A Dolby Detour
In Dolby-speak, the addition of “1” means it is the version of a speaker closer to the front of the room than the main one; a “2” denotes that it is further away from the front.
The same is true of the rear surround speakers: Lrs/Rrs is the abbreviation for the standard Left Rear Surround and Right Rear Surround speakers; Lrs1/Rrs1 would be closer to the front but still behind everyone in the listening area; Lrs2/Rrs2 would be between Lrs/Rrs on the back wall of the room.
By definition, sounds directed to the rear should be behind you. Thus, all the Rear Surround variations must be behind the entire audience, whether Lrs1/Rrs1, Lrs/Rrs, or Lrs2/Rrs2.
Thus, fewer theaters use the numbered variations of Lrs/Rrs than those of the side surrounds. After all, many larger home theaters may have three or more rows of seating. The additional Rear Surrounds are most helpful when the room is quite broad, and there is a lot of space to fill behind the rear row of seats. Relatively few home theaters are this wide.
An Ambitious Theater: Go Big or Go Home
As mentioned above, some home cinemas have three or more rows of seating. When the audience’s size becomes this large, the logical thing to do is add enough speakers to ensure that everyone has an excellent experience.
For example, in our full-length white paper (a small book, really) on the subject, our minimum recommendation for three rows of seating includes Fifteen lower and ten upper channels, as shown here:
Note that even in this spacious theater, we are not suggesting the inter-screen channels called Lc and Rc (Left-center and Right-center). We might add them if the front row was quite close to the screen. Were this the case, people in the front row might perceive “gaps” in the sound between the L, C, and R speakers that Lc and Rc would fill.
Finally, if you have a massive room with a lot of space behind the main seating area, the Altitude platform supports even something as ambitious as the following:
(Note that, in practice, theaters this large usually have many more seats than three rows of three each. We didn’t invest the time to draw in all the extra chairs.)
Object-Oriented Audio to the Rescue
You might wonder how one could use a single soundtrack for such a wide variety of applications. Wouldn’t you need different soundtracks to accommodate such extremes?
The enormous range of home cinema sizes is precisely the problem that object-oriented formats like Dolby Atmos and DTS:X seek to solve. You can read more about them in our technical blog, What Is Immersive Sound?
Jon Herron, General Manager Trinnov Audio, brings over 50 years of experience in the consumer electronics industry, focusing on high-performance audio and video. Over his career, he has worked in both large and small retail operations at the likes of Wisdom Audio, Madrigal Audio Laboratories, Mark Levinson, and Proceed. As the director of sales and marketing of Snell Acoustics, he led the company’s efforts into the home theater business in the early 1990s and participated in the launch of Home THX with Lucasfilm. His unique technical expertise and sales experience make him a perfect match for the sophisticated technologies in Trinnov products. Jon has degrees in both economics and religion from Dartmouth College.
Trinnov Audio designs and manufactures preamplifiers and processors featuring exclusive loudspeaker/room optimization and 3D sound technologies for high-end Hi-Fi & home theaters, professional studios and movie theaters. Learn more at trinnov.com.
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