Dummies guide to Dolby Atmos and DTS – read this before you buy a soundbar – GadgetGuy

Why a Dummies guide to Dolby Atmos and DTS? Because 99% of the reviews we read get it wrong and 100% of users are equally confused by the terminology.
So we developed the Dummies Guide to Dolby Atmos and DTS to demystify and clarify just what you are getting when you think what you are buying will magically add 3D sound to your TV.
Audiophiles can stop reading the Dummies guide to Dolby Atmos and DTS now. And this is about Dolby Atmos soundbars – we will add dedicated Dolby Atmos AV receivers later.
What is Dolby Atmos sound?
It expands on existing surround sound systems by adding height channels, allowing sounds to become 3D objects. Creators have a total of 128 channels routed to up to 64 speakers.
Of course, home theatre is usually Dolby Atmos 5.1.2, 5.1.4, 7.1.2, 7.1.4 and now 9.1.4. All that means is that the Dolby Atmos electronics downmix the 128 channels to the number of prime channels, e.g. 5, 7, or 9 and the number of height channels, e.g. 0, 2 or 4. Dolby Atmos must have at least two height channels or its not 3D sound – just ‘horizontal’ faux surround sound.
By the way, the .1 stands for a sub-woofer that is for frequency cut-over handling low and mid-bass. It is the same way that tweeters dont count as Dolby channels as they are frequency cut-over handling upper treble. Read more later.
Dolby Atmos is different from other Dolby standards that are simply audio channels e.g. have no Dolby Atmos metadata.

• True HD (8-channel audio and the default if an Atmos metadata is not present)
• Digital Plus (7.1 used by Windows, macOS)
• Digital 5.1 also called Dolby AC-3

What is DTS (Digital Theatre System)

• DTS:X is alternative technology to Dolby Atmos
• DTS-HD is similar to Dolby Plus 7.1
• DTS is similar to Dolby Digital 5.1

We wont go into which system is best just that they try to achieve similar things and most soundbars handle both formats.
Why bass (Sub-woofer) and treble (Tweeter) are not Dolby Atmos or DTS:X channels
Human hearing maxes out from a low of 20Hz (bass) to high of 20kHz (treble). Many older Australians may only hear to 3kHz, so they hear more muffled sounds requiring clear voice amplification!
Few speakers can reproduce 20Hz-20kHz so dedicated speakers help to fill in either end. These are not Dolby audio channels but simple frequency cut-over.
Sub-woofers amplify any bass below a cut-over frequency (usually between 80-110Hz). So, when you add a sub, you both hear and feel more bass (a combination of volume and air movement). Subs are worth adding to enhance the overall Dolby Atmos movie experience. Without it, you get whatever bass the soundbar can produce reasonable but not room-shaking.
The get Dolby Atmos or DTS:X sound you need metadata encoded content and a whole lot more
This comes from Blu-ray, some games consoles and some streaming services. It does not come from DVDs, free to air TV, or 700/1080p streaming.
Next, you must have HDMI 2.0 cables connecting all devices (information here). These are Premium High Speed (HDMI 2.0) or Ultra-High speed (HDMI 2.1) although most soundbars are still at 2.0. Gamers with the PS5 may object!
Then, the TV must support Dolby Vision/Atmos/HDR10/DTS:X metadata via eARC to the soundbar (only late model 4K and 8K TVs do this). Some soundbars have additional HDMI 2.0 inputs to connect external sources and will pass through a Dolby Vision image to the TV.
What is Dolby Atmos (and DTS:X) home theatre?
We will come to the issues of all-in-one soundbars later. For this table the terms overhead, up, up-firing and ceiling speakers are the same and refer to adding overhead sound, e.g. height. The .1 is for a Sub-woofer.

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