How To Deal With Real Surround Speakers In The Ceiling With Dolby Atmos

There is a lot of confusing and incorrect information about speaker placement for Atmos. Dolby’s guidelines can be less than helpful because they show round-down-fi ring height speakers in the ceiling. These don’t work effectively for many common applications where the seating area is low – and the guidelines do not clearly show the recommended vertical placement of side & back surrounds. So even great home theater designers put them where they used to in traditional pre-Atmos designs, high on the walls or ceiling. Unfortunately, these high locations for side & back surround compress Atmos’ overhead layer, rendering it less & less e active as they go higher on the walls and into the ceiling. With surrounds in the ceiling, there is no vertical space for Atmos to render sound objects. The vertically compressed sound field that results also distorts the size of sound objects. The ideal solution is to position side & rear surrounds with their acoustic centers, and their tweeters, in the lower half of the room. This preserves the upper half of the room for Atmos’ height layer.

Dolby Labs says that if the surrounds or other listener-level speakers are on the ceiling, the experience is

it should not be called Atmos. Using Triad’s unique selection of speaker models and versions with
specificwith different directional/dispersion patterns. First, we want ceiling-height speakers that will keep
their sound field up near the ceiling. These would be our Bronze/Silver/Gold Surrounds, whose bipole
configuration with 2 angled ba­ es directs sound left & right laterally across the ceiling, keeping their
sound up near the ceiling where we want it. Don’t worry about their InWall nomenclature; they get
installed in ceilings all the time.

Here are two solutions for back surrounds in the ceiling

Back Surround speakers can direct their sound straight down behind listeners, with no angle forward or backward and with limited dispersion on the room’s length axis to minimize direct sound leaking to listeners. The best selection here would be InWall Mini/Bronze/Silver LCRs. Figure 1
shows an example of a 5.X.2 speaker configuration with two bipole heights and 2 down-fi ring
LCR back surrounds all of the ceilings.

• Figure 2 shows a ceiling back surround alternative that can be efficient if there is a back wall
  with a reflective surface. Use angled-ba­ e speakers aimed to reflect their sound on the back
  wall at the points where back surrounds would ideally be placed. This creates virtual back
  surround speaker locations there. To calculate the ceiling speaker’s ideal location, you must take
  into account the reflection point, the speaker’s ba­ e angle (typically 45°), and the ceiling
  height. You must also select speaker models with greater output than normal because their path
  lengths to listeners will be significantly longer.
  Following these recommendations should deliver a close-to Atmos experience. Please note that Dipoles are not compatible with Atmos, but Bipoles can work extremely well.