Hi all! Steve Colburn from Triad here.
As most of you know, Triad supplied the speakers for Dolby's Atmos demo at CEDIA. I was Triad's representative at Dolby's CEDIA demo during setup and installation. Triad has been working with Dolby on the Atmos project as their development partner for 2 years so we have about as much experience with it as any others. It is very important to keep in mind, however, that Atmos electronics are only just hitting the market right now as AVRs supporting 4 height speakers. Pre pros with capabilities for additional height channels will follow, mostly in Q1 2015. This means that nobody, including Dolby and Triad, has much real world, real application experience which is needed to confidently specify what will best serve a particular room & system.
There are a lot of inaccurate and ill-informed recommendations floating around. The fact is that we have theoretical guidelines, with limited experience. Only more experience, like we got at CEDIA, will give us all the foundation we need to design & create the best performing Atmos systems. Even Dolby's Installation Guide introduced at CEDIA does not include the almost real-world systems and applications they supported at CEDIA, so they (and we) know quite a bit more now than they did when that doc was written. This is particularly true regarding ceiling height speakers, where they had little if any experience with anything other than constant directivity overheads and with seating locations that extended lengthwise in a room. CEDIA gave them and us experience with longer seating locations and angled baffle overheads.
With those caveats, let's look at a few basic guidelines we should follow in designing and laying out a home theater for best Atmos performance:
Atmos' goal is to create an overhead domed soundfield within which sound objects can be positioned and moved in 3 dimensional space. The technology to achieve this with both Atmos and legacy recordings is extremely sophisticated. It involves a listener-level base grouping of speakers that starts out as the legacy 5 and 7 channel (7.X) surround systems we are familiar with - but with a few new nuanced differences. This listener level speaker grouping is meant to be located at or just above (1 foot) listeners' ears. This replaces previous legacy recommendations for surround speaker height of 2 feet above listeners. All speakers for this level should be positioned in an even plane around the listeners' ears. Ideally monopole speakers rather than dipoles should be used to obtain the image specificity that Atmos enjoys. The 2nd layer is the Height level. The number of height speakers is designated by an additional third number in our system nomenclature. So 7.X (subs) becomes 7.X.4 with the .4 showing that there are 4 Atmos height speakers. OK?
A big factor in creating the proper sound field above the listeners is having enough space between the 2 levels. The effects diminish if there is not enough difference here or if the listener speaker level is too high above the listeners.
There are two ways to create Atmos height level. The first uses Atmos Enhanced speakers at the listener level. At CEDIA Expo Triad introduced our Atmos Enhanced & Certified InRoom Bronze LR-H. Think of this as an InRoom Bronze LCR with the Atmos enhanced height channel (separate input) on top. We call it LR-H rather than LCR-H because Atmos center channels never have height elements. They would typically replace the left & right front and left and right back or surround speakers. Since these height speakers reflect sound off the ceiling, ceilings should be flat, reflective, and within a range of approx 8 to 14 feet high. Atmos Enhanced speakers must be certified by Dolby to meet very specific and unique frequency response curves that were determined psychoacoustically to work better when reflected off the ceiling. On a personal note, I found that the enhanced speakers delivered a good "Atmos experience", slightly more diffuse than overheads at the money seats but better and less in-your-face for those seated close to the speakers.
The second way to create Atmos height level is with ceiling mounted speakers. It is important to note that presently Dolby has no Atmos certification and few standards for ceiling speakers (until they do, you won't see an Atmos ceiling speaker). They are meant to be traditional in or on ceiling speakers with no unusual frequency response curves, although they want them to produce within 3 dB max output of the main fronts at the money seat. With Dolby coming from a commercial environment they have little experience with angled ceiling speakers and because they were primarily considering limited seating areas (typically 1 row), they specified constant directivity, broad dispersion ceiling speakers. Since in real world dedicated home theaters, we tend to have our listening positions spread out over multiple rows, angled baffle speakers can be used and in many situations will be superior to downfiring ones. CEDIA may have been Dolby's first experience with angled baffle speakers.
At CEDIA Dolby introduced specific guidelines for placement of downfiring overhead speakers. These guidelines are not meant to address angled baffle ceiling speakers, I believe. The keys to selecting and placing ceiling speakers in an X.X.4 configuration are the speaker's coverage angles vs seating locations while keeping them far enough from the money seats that they become dominant. Overhead speaker selection and placement should be done on a case by case basis taking into account room dimensions, seating locations, ceiling height, & the number of height speakers used.
Dolby's CEDIA demo room had 20 seats, 4 rows of 5. The overhead speakers were Triad's (45 degree) angle baffled InCeiling Bronze/8 LCRs. I was concerned beforehand how our moderately priced ($600 ea) & performing Bronze LCRs would deal with a 20 seat theater that is larger than suggested for these. I was also concerned whether and how 4 ceiling speakers of any sort would cover the expanse of 20 seats. We positioned them for what we thought would be the best compromise for the middle seats (With 4 rows, if you stretch ceiling speakers too far apart or use straight downfiring 90 x 90 speakers, the center seats get a hole in the middle just as though you were listening to stereo speakers too far apart). I don't know of any type of speaker that would provide an uncompromised experience for all 20 seats using just 4 overheads. I can't wait until we see electronics that support more than 4 height speakers for these larger higher end home theaters.
Dolby's Atmos at CEDIA Expo is just the very beginning. While it was a promising and exciting start, it has a long way to grow and develop as we become more experienced with how Atmos responds to different applications and as new electronics are released.
I hope you found this helpful.