I'm in the very early planning stages of building a dedicated room in my basement. I am planning to wire it for exactly the 13 speaker layout you are talking about with the 4 ceiling mounted Atmos speakers placed in proper locations (whenever Dolby or someone decides more precisely where that should be). Since Dolby has mentioned that they can make it so that wide speakers can be encoded and not something that is processed from an existing mix like it is now (through Audysey and DTS), wouldn't the second generation receivers need a newer Atmos chip? Would the current Blu-Ray players even be able to support all 13 channels if we had such a new chip?
The positioning for the overhead speakers has been made fairly clear now, thanks to the Denon AVR-X5200W and Onkyo TX-NR3030 manuals
Denon shows the positioning via ranges of elevation angles:
https://www.facebook.com/media/set/?set=a.947026021981494.1073741849.522979641052803&type=1
And if you check out page 6 of the Onkyo manual, they describe the positions of the ceiling speakers as being:
Top Front = mid-way between the spot on the ceiling directly above the listening position and the spot on the ceiling directly above the Front speakers (in other words, the first reflection point on the ceiling)
Top Middle = directly overhead
Top Rear = mid-way between the spot on the ceiling directly above the listening position and the spot on the ceiling directly above the Surround Back speakers (again, the first reflection point on the ceiling).
Onkyo TX-NR3030 manual:
http://filedepot.onkyousa.com/Files/own_manuals/TX-NR3030_BAS_En_29401675_140603_web.pdf
As for left-to-right spacing of the ceiling speakers, they are meant to be directly in line with your Front Main speakers. If you had your listening position directly in the middle of a perfect circle, your Front Main speakers would be 30 degrees to the left and right of straight ahead center, and your Surround Back speakers would be 30 degrees to the left and right of 180 degrees straight behind you. You could then draw a pair of straight, parallel lines going from your Front Main speakers to the Surround Back speakers, and the Height and overhead ceiling speakers would go directly along those parallel lines. In other words, your Front Main speakers, Height speakers, overhead speakers, and Surround Back speakers are all supposed to be in a line with one another on the Left and the Right.
As a side note, Dolby does recommend using the Top Front and Top Rear positions most highly. But if you think you might want to ever try some of the other "immersive audio" formats in the future, wiring for Front Height and Rear Height speakers might also be a good idea. For example, Auro 3D audio calls for four Height speakers, all at 30 degrees elevation. Yamaha's Presence speakers also call for Front and Rear Height speakers that are at least 6 feet off the ground and just slightly wider than the Front Main and Surround Back speakers. DTS Neo:x and Audyssey DSX both call for Front Height speakers that are 45 degrees to the left and right of straight ahead center and elevated 45 degrees, too.
So everybody's got slightly different angles when it comes to the Height speakers, but the point is that all of these other "immersive" audio formats call for Front Height speakers of some sort.
Both the Onkyo manual and the Denon manual (
http://assets.denoneu.com/DocumentMaster/MASTER/AVR-X5200WE2_ENG_CD-ROM_IM_v00.pdf ) make it very clear that Atmos can use Front Height speakers instead of Top Front speakers. So in this regard, using Front Height speakers is the more flexible setup.
Now to the fun part of what you were asking
There are no additional channels in an Atmos recording! This is object-based audio. It is a new beast, and it's certainly understandable that folks are having a bit of a tough time wrapping their heads around it.
The way that Atmos works is that sound mixers now have both traditional channels as well as sound objects at their disposal. Atmos includes 9 "bed layer" channels. Those are the traditional 7 channels around the audience - Front Right, Center, Front Left, Surround Left, Surround Back Left, Surround Back Right, and Surround Right - plus Left and Right Overhead channels. If the sound mixer wants a particular sound to be played by an entire array of speakers, or to come from a specific speaker up front, they can still use channels, just like we're all used to.
But then there are the sound objects. This is a totally new way of thinking about sound. Instead of channels that are mapped to specific speakers or arrays of speakers, sound objects are just a sound with a set of X, Y, Z coordinates attached to it. Sound objects are not linked to any particular speaker or speakers. They just exist as a sound with positional metadata attached to it.
The Dolby Atmos Renderer on the playback side is what decides which speakers will play back a given sound object. The Dolby Atmos Renderer is told by the user which speakers are in use. So let's say you've set up 11 speakers. You have to start with a traditional Front Left, Center, Front Right, Surround Right, Surround Left 5.1 setup. But after that, the remaining 6 speakers could - theoretically - be just about anywhere. Maybe you've got Front Wides, Front Heights, and Top Middle speakers. Maybe you've got Surround Back, Top Front, and Rear Height speakers. Maybe you've got Surround Back, Front Wide, and Top Middle speakers. All sorts of different combinations are possible, but the user will indicate which speakers are in use during the setup of his/her AV Receiver or Pre/Pro, and the Dolby Atmos Renderer will then "know" what speakers it has to work with.
From there, the Dolby Atmos Renderer simply tries to use that X, Y, Z coordinate data and the "knowledge" or which speakers exist in the system to try and place that given sound object as closely as possible to what is called for in the positional metadata. This is why the exact same Dolby Atmos soundtrack can be played back on a 5.1.2 system, a 7.1.4 system, a 9.1.2 system, or even a 24.1.10 system!
Trinnov is introducing a Pre/Pro that can have 30 speakers and 2 subwoofers - the Altitude 32:
Introduction | Trinnov Audio
But the Altitude 32 will be using the exact same Dolby Atmos soundtracks as a more modest 5.1.2 system.
So this is the beauty of Atmos. We do not need new Blu-ray players. As long as your Blu-ray player can output Dolby TrueHD and Dolby Digital Plus bitstream audio, it is already all set for Atmos soundtracks. The Atmos information is simply an "extension" to a regular 5.1 or 7.1 TrueHD or DD+ bitstream that any bitstream output Blu-ray player can pass along.
Once that bitstream arrives at your AV Receiver or Pre/Pro, it's up to the manufacturer of that Processor to decide the maximum number of speakers it can utilize, and the various combinations of speaker positions they are willing to support. If it's a low end Onkyo AV Receiver, it might only support standard 5.1 with Top Fronts or Dolby Atmos-enabled Front speakers. If it's the Denon AVR-X5200, it can support 11 speakers with a whole bunch of different combinations. And if it's the Trinnov Altitude 32, it can support 30 speakers. But the soundtrack coming out of your Blu-ray player never changed! There are no additional channels. There's just metadata piggybacking on a regular TrueHD or DD+ bitstream signal.
So when it comes to the Front Wide speaker positions, there are no Atmos sounds that are hard encoded into the Front Wide "channels". There are no channels. But there might be sounds that make a smooth pan from the Front to the Sides, or there could be a sound object with X, Y, Z coordinates that are closest to where a Front Wide speaker would be placed. Atmos playback systems adapt. Whatever speaker positions you have, Atmos will make use of them if it's appropriate. If you go full out, Atmos can have a speaker every 15 degrees in a continuous circle all around you, plus 10 speakers overhead - Right & Left Front Heights, Top Fronts, Top Middles, Top Rears, and Rear Heights. That would be your 24.1.10 super system.
With Atmos, we need to stop thinking about speaker channels. The expanded, immersive sounds are not channels. They're just sounds with X, Y, Z coordinates. So your playback system will do the best it can with the speakers it has available to it to render those sounds as closely to those X, Y, Z coordinates as it can. That's why you can use Front Height and Rear Height speakers instead of Top Front and Top Rear speakers. The experience won't be identical, but the Dolby Atmos renderer will simply do the best it can in both cases to make it seem as though sound objects are coming from the X, Y, Z coordinates that the sound mixer gave them.
In my case, I've taken quite a shine to DTS Neo:X. For that reason, I would like to keep my Front Wide and Front Height speaker positions. And thankfully, I CAN keep those speaker positions and still use them when I'm playing Dolby Atmos soundtracks. But if I also want to use Surround Back and Rear Height or Top Rear speakers, now I'm up to a total of 13 speakers. So far, other than the Trinnov Altitude 32, there aren't any AV Receivers or Pre/Pros that will play more than 11 speakers simultaneously. Furthermore, if I ever decide to use the Dolby Surround upmixer to expand existing 2-channel, 5.1, or 7.1 recordings, the Dolby Surround upmixer will NOT output any sound from the Front Wide speakers.
So I have a choice: I could physically connect all 13 speakers - the Denon and Marantz units allow for that. If I'm using the Dolby Surround upmixer, my choice is pretty clear - I'll make use of my standard 7.1 speakers plus Front Heights and either Top Rears or Rear Heights.
Meanwhile, if I decide to use DTS Neo:X to expand my 2-channel, 5.1, and 7.1 recordings, my choice is also clear - I will use the Front Wide and Front Height speakers in addition to my standard 7.1.
But when it comes time to play a Dolby Atmos soundtrack, I might have to decide - will I use the Front Height and Rear Heights? Or maybe I'll use the Front Wides and Front Heights. OR, I could use the Front Wides and Top Rears. Or I could turn off my Surround back speakers and use Front Wides, Front Heights and Rear Heights. Any combination of 11 speakers would be open to me.
But that's where the notion of an Pre/Pro that can play back 13 speakers simultaneously comes into play. If the Marantz AV8802 or Denon AVR-X7200 can use 13 speakers simultaneously, then I won't have to choose! For Dolby Surround upmixing or DTS Neo:X upmixing, I'm still using "only" 11 speakers - and it's decided for me which 11 speakers it will be. But for actual Dolby Atmos soundtracks, there's no technical reason on the soundtrack side why I couldn't use all 13 speakers at once. All that is needed is the manufacturer's decision to make that possible. Trinnov decided to make it possible to use 30 speakers all at once. And Atmos at home itself allows for as many as 34 speakers. And even that 34 speaker limit is qualified by Dolby as being "at this time". In full sized cinemas, up to 64 speakers can be used. And literally the exact same Atmos soundtracks can be taken from the cinemas and used in homes. So it's technically possible that one day, home theaters could use as many as 64 speakers when playing back Dolby Atmos soundtracks
