11.1 Surround isn’t exactly standard for must studios, and it certainly isn’t standard for the independent filmmaker’s home editing cubicle. To understand how this incredible 3D audio system works, however, is important for even the 2D systems (5.1, 7.1) and it’s totally dope to fool around with.
Things to watch out for in any surround system speaker placement include:
- speakers too low/high
- center channel on the ground – aimed at the floor
- surround speakers too high – to far away
- mid speakers too close -WAY too close
- left/right speakers not equidistant to the listener
- left/right speakers not equidistant from the center speaker
- subwoofer under a table or some other fangled place
- generally all speakers are different distances from the listener
- height speakers are not acoustically isolated from the ceiling or walls
11.1 and all height capable systems creates incredible creativity for the filmmaker and mixer to powerfully immerse the audience in a soundscape otherwise not possible in 2D systems. You can easily create these kinds of scapes with Spatial Audio Designer on any pair of headphones, but if you’ve got a theatrical delivery, it’s far more difficult – and you may be relegated to 2D spaces. Still the ability to place ambiences, birds, and even helicopters and other SFX into height panoramic fields is something to consider – and possibly consider having a separate headphone mix for.
Still, in any surround speaker setup, you must have all speakers equidistant to the listener or else strange phasing and delay issues will keep the mix you’re hearing from translating anywhere else. You also need to have the speakers you’re using “tuned” and balanced to put out the correct volumes.
What? You don’t know what any of this means? Oh dear. Well, let me illuminate with the following short video. We go over all of this in depth in the “Workspace” Volume of the Pro Member Education but I’ll give you the general gist here. We also cover this in the article called 5.1 Surround Sound – The Right Placement:
In this clip, you’ll notice a few things which are critical to implement into your system – whether home theater or mixing space – regardless of the surroundings or situation:
Equidistance
Notice that all of the speakers – including the Sub Woofer – are exactly the same distance from the listener. This means that your L/C/R speakers are not in a straight line across. If you did that, the center speaker would be closer, and not only be louder but its sound would impact the listener earlier – which makes it seem even louder.
Surround Position
Notice the surround and “mid” speakers also are equidistant, and although the mid speakers don’t fall into a magic triangle, the surrounds do. Also note that the surrounds should be elevated about 10º or so and refocused to the back of the heads of the listeners to better simulate how it is in a theater (or how it will be).
Sub Woofer Position
There’s quite a bit of controversy over where to put the sub woofer. There is zero controversy over it being equidistant to the listener in comparison to the other speakers. However, check with you owner’s manual and discover if the manufacturer suggests a position. If it says, say, “place against a wall,” I’d recommend you follow that instruction. The trouble comes when the wall placement of the sub woofer makes it farther away than the rest of the speakers. When this happens, you’ll need to delay the rest of the speakers to compensate for this otherwise your sub woofer will be too quiet and your mixes will have too much LFE volume.
You compensate for this by delaying the other channels 1.1308 ms/ft. So if the Sub is 1 foot farther away, then the other speakers get delayed 1.1308 ms. Bear this in mind, since 1 frame of 23.976 video is roughly 42 ms, if your sub is 20 feet farther away, your speakers will be delayed 22.616 ms – which is a half a frame. Not bad, but could cause issues with syncing audio as you listen. Of course, if your sub is that far away, you’ll have to drive it so hard to compete with the other speakers that it might be a better idea to rethink your positioning of it – because a sub driving that hard (perhaps 8 times louder than the other speakers) will certainly get the police called on you if not having you wearing a sub woofer speaker cone around your neck.
This is also the situation you’d use for your mid speakers when they are – ever so commonly – too close to the listener. In this case, should the mid speakers be closer than the other speakers, you consider the speakers which are furthest away as “ground zero” and delay all other speakers according to their difference in distance from that speaker to the listener.
Those Mids
The 7.1 mixing format is by far my favorite 2D mixing situation, because you can create phantom “center” all the way around the room and at every juncture. It’s truly “full surround” and it’s why nearly all height speaker iterations have the 7.1 array as it’s minimum requirement. Although building a sweet spot for a single listener is fine, we almost never are the only persons to listen to our system. Even if it’s you and a client, your listening position will need to take into account two or more folks sitting side-by-side. This doesn’t pose too many problems except for the mid speakers. Where two people sit next to each other, one person will completely block the other from the opposite mid speaker and vice versa. As a result, I recommend moving the mid speakers 10º forward in order to clear the face of the person sitting next to you.
Height
Height speakers are the crowning gem of 11.1 systems, and they’re also the most difficult to deal with. Difficult to attach to ceilings and walls without acoustically coupling them to your studio/home at the same time, focusing these speakers makes installation of the height speakers very difficult. Although it takes quite a bit of effort and time to get the placed and focused, the rewards of having such a system are staggering. Generally, height speakers quickly become “ground zero” for being the farthest from the listener. All other speakers get delayed to the distance of these speakers. Ideally, these four speakers are each equally equidistant from the listener, otherwise complex delay lines need to be used to compensate. It’s also adviseable to have these be passive speakers (needing amplification), because that way changing their volume can be done from a separate amplifier on the ground rather than up on a ladder at each speaker.
Notice the “Magic Square” which is set up between the height speakers? Also notice that from a bird’s eye view, those speakers are actually inside the magic triangle of the 7.1? These characteristics further assist in managing height speakers which are usually farther away than the floor placed ones.
Volume
This is another massive issue among audio mixers and one which they love to throw mindless theory at you about. We cover this in depth in the Workspace Volume, but I’m just going to leave this here and you’ll have to trust me about it.
If you’re mixing for web and listening at 75dB, using pink noise generation in each speaker one-at-a-time, tune your speakers the following way:
- L/C/R-LFH/RFH: 75dB
- Ls/Rs-Lm/Rm-LSH/RSH: 72dB
- LFE: 79dB
If you’re mixing for DVD/BRD @80dB:
- L/C/R-LFH/RFH: 80dB
- Ls/Rs-Lm/Rm-LSH/RSH: 77dB
- LFE: 84dB
If you’re mixing for theatrical @ 85dB:
- L/C/R-LFH/RFH: 85dB
- Ls/Rs-Lm/Rm-LSH/RSH: 81dB
- LFE: 90 dB
The Magic Triangle
This mysterious geometric reference has nothing to do with anything in Bermuda, but it is the perfect place for you, the listener, to sit and from which point you should measure your speakers. If you’re closer to one set of speakers, those speakers will be “louder” to you than the others and your ability to create a mix which will translate widely will narrow. For surround we want to take into account a circular presentation to figure out the distance of our speakers, but stereo must always be taken into account as a triangle for both the front and surround speakers. Take a look at this video and see what I mean.
Notice the center speaker is behind the triangle? Looks like it’s farther away, right? I promise you it isn’t. If you take a tape measure and measure the lengths, you’ll see that geometry beats naked eye. However, the magic triangle must ALSO be had. How do we get both to work? Well, in the Workspace Volume I recommend having two guys and two tape measures, and it’s not easy. Generally, you figure out how far apart you want your L/R speakers, then put yourself in a position so you’re at the peak of the magic triangle. Once you’ve established that, you add your center channel half-way between them. Then turn around and make a magic triangle for your surrounds.
If you follow these instructions and place your speakers where the video suggests, you’ll have a much easier time having your mixes translate to theaters, home theaters, and cars. It’ll also have your home theater sound much more like what the filmmakers’ originally intended.
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