Question:
I’ve seen new receivers that are advertised at 11.2. What are the additional channels used for and are they discrete channels or matrixed?
– Chris B
Oklahoma City, OK
Answer:
You ask a very good question. In order to answer your question fully, it is first useful to define “discrete” channels versus “matrix” channels. The latter has nothing to do with the futuristic trilogy starring Keanu Reeves (which coincidentally has GREAT surround sound encoding), but rather the way the audio channels are encoded.
“Discrete” channels are ones that carry fully unique and independent audio signals. The most common example of this is stereo, where the right and left channels carry independent signals so you can identify, say, a drum beat, as coming from the right or the left side.
“Matrix” channels are a blend, or matrix, embedded in two discrete audio channels. The recording/mastering studio blends the third and fourth channels in the original two discrete channels, and the matrixed channels are extracted during the decoding process to end up with four channels.
The nomenclature for surround sound can be confusing to the uninitiated, but is fairly simple in concept. The audio channels are displayed as a numbers, usually in an “X.Y” format. The “X” is the number of full range (or mostly full range) audio channels; the “Y” is the number of low frequency effect channels (think subwoofers). So a 5.1 surround sound signal would have information for five full channels (FR, FL, C, SR, SL) and one low frequency effects channel (LFE). Because the LFE carries the burden of bass from all (or mostly all) of the other channels in the setup, there is almost no real “localizable” sound. So to make a “X.2” signal, the second LFE signal is simply a duplicate of the first.
There are two major companies who encode surround sound for home theater. One is Dolby and the other DTS. Think “Coke vs Pepsi” or “Mac vs PC” and you will have some idea of what we are talking about. Both produce a myriad of surround formats, and a myriad of ways to produce each of them. Going into detail about all of them is far beyond the scope of this QA, but I will try to touch on the more familiar formats here, so when you see “Dolby ProLogic II” or “DTS-HD” on home theater electronics, you will have an idea of what that actually means.
5.1
This is the surround format we are probably the most familiar with in terms of watching movies in our home theaters. Both Dolby and DTS offer all 5.1 channels as discrete, and are simply “Dolby Digital” and “DTS”. There are also versions from each firm that can matrix 5.1 from stereo encoding. These are “Dolby ProLogic II” and “DTS Neo:6”. This speaker arrangement consists of:
Front right (FR)
Front left (FL)
Center (C)
Surround right (SR)
Surround left (SL)
Low frequency channel (LFC)
7.1
Now we arrive at the next step up from 5.1 surround sound. This adds discrete surround back right (SBR) and discrete surround back left (SBL) channels to the traditional 5.1 makeup. These additional channels are placed further back than the SR or SL, on the rear wall, about 2/3 the way from the center to the right and left corners respectively. These additional channels make for a smoother, more realistic transition as sound moves around the listener.
Both Dolby and DTS have formats that incorporate eight channels of discrete audio. There are, however, two flavors of discrete 7.1 from each: one lossy and the other lossless. Dolby calls it’s standard 7.1 encoding “Dolby Digital Plus” and the lossless version “Dolby True HD”; DTS has “DTS-HD” and “DTS-HD Master Audio”, respectively. Both the “Dolby True HD” and “DTS-HD Master Audio” formats are bit-for-bit, uncompressed copies of the original studio masters. Dolby also offers a matrix 7.1 format, “Dolby ProLogic IIx”. Most Blu-ray movies are in 5.1, while perhaps 5% are in 7.1.
Front right (FR)
Front left (FL)
Center (C)
Surround right (SR)
Surround left (SL)
Surround back right (SBR)
Surround back left (SBL)
Low frequency channel (LFC)
9.1
At this point, we have ventured off the discrete sound map, and trust me, it is easy to get lost in here! The 9.1 format adds matrix channels to 7.1 formats as front right and front left effect speakers. To add to the already dizzying array of choices, these channels can be used as either height or width effect speakers rendering front right height (FRH) and front left height (FLH), or front right width (FRW) or front left width (FLW). When used for height effect, the speakers are generally mounted on the wall above the FR and FL channels at about a 45 degree incline from the listener. When used for width effect, the speakers are mounted on the side walls, preferably half way between your center channel and the SR and SL at roughly ear level.
“Dolby ProLogic IIz” and “DTS Neo:X” are the choices here.
Front right (FR)
Front left (FL)
Front right height (FRH) or Front right width (FRW)
Front left height (FLH) or Front left width (FLW)
Center (C)
Surround right (SR)
Surround left (SL)
Surround back right (SBR)
Surround back left (SBL)
Low frequency channel (LFC)
11.1
This format adds the right and left effect speakers (height or width) that were not included in the 9.1 setup. “DTS Neo:X” is currently the only encoding format I am aware of that can even generate 11.1 sound. Now we have, in all it’s splendor:
Front right (FR)
Front left (FL)
Front right height (FRH)
Front right width (FRW)
Front left height (FLH)
Front left width (FLW)
Center (C)
Surround right (SR)
Surround left (SL)
Surround back right (SBR)
Surround back left (SBL)
Low frequency channel (LFC)
The speaker placements and order of addition I have mentioned above are not meant to be absolutes, but rather to give you a fairly good idea of the optimal speaker placement. In fact, Audyssey, who designed the room acoustic correction software found in many home theater receivers, would rather you add FRW and FLW before FRH and FLH, and all of those before you add in the more common SBR and SBL!
So here we arrive at the sad truth. There is no fully discrete 11.2 format. You can only remain discrete up to 7.1; past that however, you must succumb to the matrix! Both Dolby True HD and DTS-HD Master Audio 7.1 formats can be matrixed into any number of channels by your processor or receiver, limited only by your space and budget. As mentioned earlier, the only studio format that gets close (to my knowledge) is “DTS Neo:X”, which can matrix an 11.1 sound from 5.1, 6.1, or 7.1 channel material. Since 11.1 and 11.2 is essentially the same, with only the low frequency channel repeated, looking for a receiver with “DTS Neo:X” is likely your best bet for now.
On a side note, it must have aggravated Dolby to no end that DTS was first to the 11.1 table. In response (or at least it makes for a better story this way), Dolby has gone completely over the top and recently introduced a 62.2 surround format dubbed “Atmos”. This is only available in ~300 commercial theaters, and involve a lot more power amplifiers and speakers, so I don’t expect to see any “Atmos” receivers on retail shelves in the forseeable future.
– Robert Ebeling, III
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View Comments
Well written and to the point. Thanks for details!
If I had enough amps to drive 62 speakers, I wouldn't need to heat my basement.
Well said my friend, well said!
11.2 surround sound, more more more speakers. I overheard a Sony rep in a class teaching engineers that more sound channels were gimmicks to get people to buy more stuff. More chrome plated plastic devices with blinky lights for everyone!
Sounds like this is a perfect spot for a 3rd party to invent a device that will allow the split of all the channels to a different source (aka an amplifier) to supply the power needed for the sound. That would eliminate the need for the receiver to push the power needed for 60+ speakers. The biggest problem I foresee is people placing speakers in their floor!
Surround speakers belong on the sidewalls that is the common way that we see at cinemas if cinemas placed them on the floor with larger PA type not same size as the stage channels you get the idea then everyone would be climbing over them or walking around the when we see stacks of PA speakers at night club or outdoors concert.
Side back wall surrounds belong on the walls it also reinforces the bass range stacking them on the floor near a seat is bit of waste money when most of the bass is going to lack a little bit. Mount them on the side and rear walls kt keeps them out of the way.
Philip,
I am glad you enjoyed the article! I love digging into the details, but sometimes you just want a thorough, yet concise, explanation. I will try to keep this trend going in my future writings as well.
Cheers!
So I mostly see the 9.2 or 11.2 channel receivers out there, but I did fine a 13.2 channel receiver or some 11.2 that are expandable to 13. Do you have an article on how an Atmos, DTS:X or Auro-3D set up should look? If not I think that would be great since receivers only seem to be getting bigger. Plus I would like to know order of most prominent and most needed speakers in a height set up. I currently have 5.2.2 with SVS Prime Elevations mounted on my wall above my towers because I have a vaulted ceiling with popcorn, and their configured as top front instead of front height because I have them so high and I get a better sound out of them. Thanks.
Sound that we hear is where we are standing or lets say if we was floating in midair we would hear a helicopter below us. Yes below us as we can hear sounds below our hearing. All this marketing for height surrounds to me is old news that goes back decades to few local cinemas in Bournemouth located on the south coast of the UK.
I've heard it and been listening to surround channels made up from sidewall to back wall which is the common way or like horse shoe U shape. The other was with same sidewall rear wall and clusters evenly spread around flush mounted within the ceiling of the days of STAR WARS, Close Encounters to name the few and many more I have listened too at Odeon Bournemouth screen 1 and screen 2.
Screen 1 upstairs cinerama curved screen had its x6 surrounds flush in the ceiling.
Screen 2 that no longer exists was gutted into shoebox screens early 1989 but in some parts of the refit the original overhead surrounds can still be seen even thou covered up with bit of wood and painted over to match the rest of the ceiling.
Screen 2 was sidewall rear wall I think 10 or maybe two less for side/rear walls and around x6 I think for the ceiling. Robocop (1987) freaked me out when ED-209 was relieved and walked into the office hearing a sound moving so beside me and above in a sense of way that made me flinch react or sort of participate with the sounding scene.
Few years later I had a job with UCI cinemas a new local plex that opened up nearby with 10 screens. What was surroundingly interesting about the auditoriums two main large ones and seven small ones was they each had wait for it... OVERHEAD SURROUND. I thought that would all get your attention!
Someone posted a picture that I saved on facebook few years ago and its been some time since I seen how the one of two main large auditoriums originally was back around 1989. The two main large screens was screen 5 and screen 6 with a narrow corridor that had rollers on the wall so that a film can be "inter-locked" with another screen with few minutes delay time when passing though the film-gate then few seconds later makes its way up a vertical roller then across the horizontal rollers to the next projector.
https://uploads.disquscdn.com/images/1e72e81e666a6dfec5cc40ac27c3e0f92c9e7eaee444ff23b8fe2793c67d1465.jpg
All screens used EV speakers three stage and smaller screens used x5 surrounds on the ceiling with fifth one near the rear back near the entrance and yeah it was "immersive" with a Dolby Stereo CP55 with sometimes running Dolby SR depending on which prints are sent but commonly Dolby Stereo A type did the same trick its only a NR noise reduction system to "make films sound better".