Dolby Atmos Best Practices for Proper Home Playback

gene

gene

Audioholics Master Chief
Administrator
We recently hosted a livestream with recording and mixing engineer John Traunwieser, whose credits include work on multiple Star Wars movies and other big titles, to discuss the ins and outs of Dolby Atmos. This article offers a brief explanation of how Dolby Atmos works, and how best to set up your home theater for a successful Atmos experience. It also addresses some common mistakes and misconceptions regarding Atmos setup. We discuss theatrical vs nearfield mixes and streaming vs optical disc quality.

According to John Traunwieser, objects are generally used for two things, and two things only:
  1. Atmospheric sounds that you want to fill the space, filling in the gaps with extra speakers.
  2. Point source sounds. These are sounds effects: things whizzing by, or particular effects that you want to localize better.

Dolby-thumb.jpg


Read: The Truth About Dolby Atmos & Best Set Up Practices in the Home

 
gene

gene

Audioholics Master Chief
Administrator
How Many Speakers Do you Need for Proper Dolby Atmos Playback in the Home?

 
S

shadyJ

Speaker of the House
Staff member
Very good article, Jacob! Very informative and will certainly be enlightening for many readers on what Atmos is and isn't, since there is still much confusion surrounding the format.
 
J

jeffca

Junior Audioholic
The only thing I'd quibble with is the geometry shown in the overhead showing the 7.1.4 Speaker Layout speaker placement looking down into the room.
  • The left and right speakers should be 30° out from the main listening position at the very least for stereo. For surround or LCR setups, where you have the center speaker to firm up the front imaging, you may find 35-45% to work even better.

  • Jamming your sofa way to the back of the room is not optimal.

  • Going along with my last point, having the surrounds & rears so close the the listening position is really not a good idea. That really skews the audio from those speakers drastically off-center if you are not in the sweet spot.

  • To go along with the two previous points, the surrounds should at least be at 110° from center. Ideally, 120° so that you get a better surround field (with a wider front geometry) and so that no one's head is blocking the surrounds to other listeners.

  • To go along with all of this, the rears then can be set up with the narrow spacing (150°) suggested. DTS a long time ago used to suggest rear speakers having a narrow spacing. So did Lexicon.

  • Finally, a single sub? In a home theater? Really? Yeah, that will work well (not!).
I realize that this isn't a real design schematic or architect's drawing, but this could have been done better by who ever made it.
 
E

easyrider2020

Audiophyte
Just an erratum in Jacob's article. There are two drawings side by side comparing home to cinema Atmos speaker layouts. The home drawing is labelled 7.1.4.
This is incorrect. What is shown is a 5.1.4 layout. Otherwise, thank you for the rather informative article, Jacob!
 
gene

gene

Audioholics Master Chief
Administrator
The only thing I'd quibble with is the geometry shown in the overhead showing the 7.1.4 Speaker Layout speaker placement looking down into the room.
  • The left and right speakers should be 30° out from the main listening position at the very least for stereo. For surround or LCR setups, where you have the center speaker to firm up the front imaging, you may find 35-45% to work even better.

  • Jamming your sofa way to the back of the room is not optimal.

  • Going along with my last point, having the surrounds & rears so close the the listening position is really not a good idea. That really skews the audio from those speakers drastically off-center if you are not in the sweet spot.

  • To go along with the two previous points, the surrounds should at least be at 110° from center. Ideally, 120° so that you get a better surround field (with a wider front geometry) and so that no one's head is blocking the surrounds to other listeners.

  • To go along with all of this, the rears then can be set up with the narrow spacing (150°) suggested. DTS a long time ago used to suggest rear speakers having a narrow spacing. So did Lexicon.

  • Finally, a single sub? In a home theater? Really? Yeah, that will work well (not!).
I realize that this isn't a real design schematic or architect's drawing, but this could have been done better by who ever made it.
These are generic layout diagrams to show general speaker positions. Of course we recommend multiple subs for EVERY application. We've been preaching it since I started the website over 20 years ago. I agree the seating should NEVER be up against a wall. I usually set my theaters up so the seating is 2/3 the way back into the room. This takes you out of a maximum pressure area and gives you enough distance from the front wall for proper soundstage imaging and adequate distance from the screen for proper viewing.
 
gene

gene

Audioholics Master Chief
Administrator
Just an erratum in Jacob's article. There are two drawings side by side comparing home to cinema Atmos speaker layouts. The home drawing is labelled 7.1.4.
This is incorrect. What is shown is a 5.1.4 layout. Otherwise, thank you for the rather informative article, Jacob!
Good catch. I updated the article.

dolby-layout.jpg
 
S

sterling shoote

Audioholic Field Marshall
My only interest in Dolby ATMOS is to enjoy Apple Music’s Spatial Audio, which might elevate my overall pleasure from recorded music as I have occasionally experienced from 5.1 SACDs and Blu-ray Music Discs. As I understand it I can get the Spatial Audio experience from an Apple TV connected to my OPPO-205 operating as a pre-pro. My confusion is what component services my Apple Music app, currently I have the app running on an M1 iMac, iPhone, and Windows 10 laptop, all interfaced to play on three different audio systems.
 
gene

gene

Audioholics Master Chief
Administrator
My only interest in Dolby ATMOS is to enjoy Apple Music’s Spatial Audio, which might elevate my overall pleasure from recorded music as I have occasionally experienced from 5.1 SACDs and Blu-ray Music Discs. As I understand it I can get the Spatial Audio experience from an Apple TV connected to my OPPO-205 operating as a pre-pro. My confusion is what component services my Apple Music app, currently I have the app running on an M1 iMac, iPhone, and Windows 10 laptop, all interfaced to play on three different audio systems.
You need a atmos AVR. Your OPPO doesn't decode Atmos.

 
}Fear_Inoculum{

}Fear_Inoculum{

Senior Audioholic
Great videos. Very informative. Glad to see that I'm doing it right according to the information in the videos.



Cheers.
 
P

psraj

Audiophyte
Very in-depth and informative video. This may be a wrong question for this thread, but, I know DTS:X doesn't support more than 7.1.4 yet. Does having a 7.1.6 setup negatively impact DTS:X in any way? I am not clear on how processors like Marantz or Anthem handle channel mapping in such a layout? Would the 2 additional top-middle speakers would just be ignored for DTS:X?
 
VoidX

VoidX

Audioholic Intern
Finally a really good article in the topic that everyone seems to get wrong in the technical level. There's very little valuable human-readable documentation about the actual inner workings of Atmos, but you got most of it on point, only one and a half things need a bit of clarification.

"Are there some places where you can't place objects?"
Yes, you can't pan perfectly up the screen in a reference room, since the top fronts are not in the screen. The renderer's speaker locations completely differ from the recommended placement, for example, they're at the edges of the box that simulates the room, sides are perfectly on the side's middle, and all tops are above a ground layer speaker. The inner channel locations are in table B.10 of ETSI TS 103 420 V1.2.1. In cinema, where the inner locations match with the real ones, the tops are present for each or each other (since newer rooms) surround, fronts are not included.

"the bitrate used for objects is “a lot lower than you would think,”"
There's no such thing as Atmos bitrate. If you mean the few bytes that encode the JOC matrix per frame, then yes, it's <3% of the overall stream size, but the issue is not that. Atmos is disassembling each full bandwidth channel to 10 bands, and mixes these 50 or 70 bands to new objects. The Atmos metadata only contains this mixing matrix, so the actual audio is coded with the other channels. What you hear when you mute the bed/ground channels (that's possible with a single click in Cavern), is the result of non-perfect alignment (not enough bands, only a few bits per matrix element). There can't be more bands, as this process is so slow that it takes 160x more performance to render this than regular DD+. The Fourier transforms needed for the QMFB transformations in the JOC matrices can't be sped up, since the DFT equations are distorted in such a way that FFT can't be used. The performance for decoding DD+ Atmos is about 6-7x real-time on a Ryzen 5600. Real-time isn't even possible with hardware from a few years ago, that's why external ICs were always needed in home cinema applications.
 
A

alfred3

Audiophyte
Hi Gene
what can be done if i want a 7.1.4 setup but my mlp/ sofa is at my back wall and no space at back or a way to change the setup my living room is 6x6 m
thank you
 
William Lemmerhirt

William Lemmerhirt

Audioholic Overlord
Hi Gene
what can be done if i want a 7.1.4 setup but my mlp/ sofa is at my back wall and no space at back or a way to change the setup my living room is 6x6 m
thank you
Change expectations and do 5.1.2.
Putting rear surrounds on the back wall where the couch is against it is very distracting imo, but people do it. Also. The rear top/heights should be behind the listener for proper front to back overhead panning. I’ve seen .4 overheads with the couch against the wall in a top middle front height designation, but Atmos is not designed for that so imo, 5.1.2 is the best choice. Maybe find another room? Can’t move the couch ahead? What’s the room dimensions?
 
A

alfred3

Audiophyte
Hi William
Thank you for your rapid replay . the room dimensions is 6x6 meters but i cant move the couch ..
in 5.1.2 set up the 2 is the atmos speakers correct? where to put them (distance from MLP to wall in front )
and if i want them to be in ceiling what is the best choice/brand?
Thank you
Alfred
 
William Lemmerhirt

William Lemmerhirt

Audioholic Overlord

Here’s Dolby’s guide for 5.1.2. It looks like they’re indicating to keep them in line with the mains, but that’s not really the case. How tall is the room?
What brands are available to you? What country are you in?
 
A

alfred3

Audiophyte
My room is 2.40 meter high. my LCR are monitor audio i don't have any problem to purchase internationaly
 
Last edited:
P

Pasi Vilonen

Audiophyte
Hello all the experts :)

The bottom layer always is presented with angled speakers towards listening position.

Top speakers always point downwards.
But shouldn't they be angled towards listening position so that speaker on axis plays correct?

I see a lot of measurements of speakers that points out the importance good spread of a wide on axis performance.

Is on axis underrated as I see many people play straight out to the room from the front wall with ex inwall speakers and front high speakers.
speakers.

My personal preferences is that always point speakers towards listening position.

Have a nice day!
 
G

Gys Florian

Enthusiast
"As for the number and configuration of speakers, a 7.1.4 layout is the gold standard that enthusiasts should shoot for whenever possible. That’s not to say that it’s the best configuration for everyone. If your room’s front-to-back length is on the short side, you may only be able to accommodate a 5.1.4 system."

What minimum front-to-back lenght is needed to accommodate a 7.1.4 system ?
 

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