The Final Encompass Sound Information: Each Format Defined


Encompass sound is strictly what it appears like: It’s a class of merchandise and applied sciences designed to immerse you in audio from all sides, all angles, and more and more, from all heights too.

We’re going to take a really deep dive into precisely the way it works and the applied sciences that introduced us to at this time’s state-of-the-art. However earlier than we do, let’s take a fast have a look at the Dolby Atmos and DTS:X, the 2 {surround} sound ecosystems that everybody’s speaking about.

Objectively higher sound

You’ll have heard one thing about 3D or “object-based” {surround} sound, which started making waves round six years in the past as a part of a push to modernize struggling film theaters.

You see, earlier than the coronavirus pandemic upended life as we knew it, theaters had been within the midst of a renaissance of types. Not solely had been premium film homes proliferating, providing luxurious seating and restaurant-quality meals, however many venues had been additionally upgrading their sound programs utilizing Dolby’s revolutionary Atmos expertise.

Theater audio system have all the time been capable of crank out some critical decibels, however earlier than Atmos, they weren’t all that refined by way of their underlying tech. For example, if you happen to had been watching an motion film and there was an explosion on the appropriate facet of the display screen, half of the audio system within the theater would all play that very same sound.

With Atmos, the sounds in a theater may now come from distinct areas decided by the skilled audio mixers that had organized them. Recognized within the business as “object-based” sound expertise, Atmos allowed for as much as 128 distinct sound objects to be represented in a given scene, which could possibly be routed to as much as 64 totally different audio system.

Rivals like Digital Theater Techniques (DTS) quickly adopted swimsuit, with the corporate boasting that its DTS:X expertise may produce extra particular person audio feeds than Atmos, which was hard-capped at 64. This meant that, theoretically, theater operators had been restricted solely by their urge for food so as to add additional audio system and amplification.

With the event of suitable A/V receivers, the battlefield shortly shifted to the lounge. At present, most high quality A/V receivers help object-based {surround} sound, and the tech that helped revitalize film theaters is now accessible within the residence.

Digital music can also be getting the Atmos remedy, with various streaming companies (Tidal, Amazon Music, and Apple Music, to call a couple of) already profiting from Dolby Atmos Music, an offshoot of its theatrical, object-based sound expertise.

Atmos isn’t the one payer on this area, both, as opponents like DTS:X and Sony’s 360 Actuality Audio will look to problem Dolby for sonic supremacy within the months and years forward.

This being a top-to-bottom {surround} sound information, nonetheless, we have to journey again earlier than we are able to transfer ahead. In case you’re a layperson seeking to perceive how Atmos and its opponents can revolutionize your private home theater, you’ll want a fast {surround} sound primer and a quick historical past lesson earlier than constructing your setup.

Encompass sound 101

We’ll get to the historical past of {surround} sound and the specs of all of the competing codecs in only a minute — however first, let’s get the fundamentals out of the way in which. Understanding a couple of core ideas will assist orient you to be able to comply with the dialog to come back, so right here’s what you must know earlier than we get right down to the nitty-gritty:

The audio system

Encompass sound, at its most simple, includes a set of stereo entrance audio system (left and proper) and a set of {surround} audio system, that are normally positioned simply to the edges and simply behind a central listening place. The subsequent step up includes the addition of a middle channel: A speaker positioned between the entrance left and proper audio system that’s primarily liable for reproducing dialogue in motion pictures. Thus, now we have 5 audio system concerned. We’ll be including extra audio system later (tons extra), however for now, we are able to use this primary five-speaker association as a springboard for moving into the totally different codecs.

The matrix

No, we’re not speaking in regards to the sci-fi franchise starring Keanu Reeves. On this case, matrix refers back to the encoding of separate sound indicators inside a stereo supply. This strategy was the idea for early surround-sound codecs like Dolby Encompass and Dolby Professional Logic and was motivated partially by the restricted area for discrete info on early audio-video media, resembling VHS tape.

Professional Logic

Utilizing the matrix course of, Dolby’s Professional Logic {surround} was developed to encode separate indicators inside the primary left and proper channels. Dolby was capable of permit residence audio units to decode two additional channels of sound from media like VHS tapes, which fed the middle channel and {surround} audio system with audio. Due to the restricted area, nonetheless, matrixed {surround} indicators got here with some limitations. For example, the {surround} channels in primary Professional Logic weren’t in stereo and had restricted bandwidth. That signifies that every speaker performed the identical factor and the sound didn’t contain a lot bass or treble info.

Encompass sound historical past

OK, so now that you understand what {surround} sound is and what the present state-of-the-art tech is able to, let’s discuss how we bought right here.

It was the summer season of ’69. We’re not speaking in regards to the Bryan Adams tune right here; we’re really referring to the primary time {surround} sound turned accessible within the residence. It was referred to as Quadraphonic sound, and it first appeared on reel-to-reel tape. Sadly, Quadraphonic sound, which offered discrete sound from 4 audio system positioned in every nook of a room, was complicated and short-lived — no due to firms battling over codecs (sound acquainted?). Immersion in a three-dimensional audio sphere was to not be given up on, nonetheless.

In 1982, Dolby Laboratories launched Dolby Encompass, a expertise that piggybacked a {surround} sound sign onto a stereo supply by means of matrix encoding. Since then, Dolby, DTS, and others have helped advance the state of residence {surround} sound with quite a lot of iterations. Within the subsequent part, we hint this evolution — from the usual 5.1 setup to state-of-the-art, object-based {surround}. 

Encompass sound takes form

Dolby Digital 5.1/AC-3: The benchmark

Bear in mind LaserDisc? Although the medium was first invented in 1978, it wasn’t till 1983, when Pioneer Electronics purchased a majority curiosity within the expertise, that it loved any sort of success in North America. One of many benefits of LaserDisc (LD) was that it offered much more cupboard space than VHS tape. Dolby took benefit of this and created AC-3, now generally known as Dolby Digital. This format improved on Professional Logic in that it allowed for stereo {surround} audio system that might present larger bandwidth sound. It additionally facilitated the addition of a low-frequency results channel — the “.1” in 5.1 — dealt with by a subwoofer. All the data in Dolby Digital 5.1 is discrete for every channel — no matrixing mandatory. Sorry, Keanu.

With the discharge of the movie Clear and Current Hazard on LaserDisc, the primary Dolby Digital {surround} sound hit residence theaters. By the point DVDs got here out in 1997, Dolby Digital had turn into the default {surround} sound format. To this present day, Dolby Digital 5.1 is taken into account by many to be the {surround} sound commonplace and is nonetheless included on most Blu-ray discs.

Picture courtesy of Dolby Labs

DTS: The rival

What’s a expertise market and not using a little competitors? Dolby kind of dominated the {surround} sound panorama for years. Then, in 1993, DTS got here alongside, offering its personal digital {surround} sound mixing companies for film manufacturing, first hitting theaters with Jurassic Park. The expertise ultimately trickled right down to LaserDisc and DVD however was initially accessible on a really restricted collection of discs. DTS makes use of a better bit fee and, subsequently, delivers extra audio info. Consider it as much like the distinction between listening to a 256kbps and 320kbps MP3 file. The standard distinction is noticeable, however as with so many audio-related comparisons, not everyone seems to be bought on it.

6.1: Kicking it up a notch

In an effort to reinforce {surround} sound by increasing the “soundstage,” residence theater firms created 6.1, which added one other sound channel. The sixth speaker was to be positioned within the middle of the again of a room and was subsequently known as a again {surround} or rear {surround}. That is the place some confusion started to swirl.

Individuals had been already used to pondering of and referring to {surround} audio system (incorrectly) as “rears” as a result of they had been so typically positioned behind a seating space. Really helpful speaker placement, nonetheless, has all the time referred to as for {surround} audio system to be positioned to the edges and simply behind the listening place.

The purpose of the sixth speaker is to offer the listener the impression that one thing is approaching from behind or disappearing to the rear. Calling the sixth speaker a “again {surround}” or “{surround} again” speaker, whereas technically an correct description, ended up being simply plain complicated.

To make issues much more complicated, every firm supplied totally different variations of 6.1 {surround}. Dolby Digital and THX collaborated to create a model known as “EX” or “{surround} EX.” It makes use of the tried-and-true matrix encoding methodology to embed the sixth channel contained in the left and proper {surround} indicators.

DTS, alternatively, supplied two separate 6.1 variations. DTS-ES Discrete and DTS-ES Matrix carry out as their names recommend. With ES Discrete, particular sound info is programmed onto a DVD or Blu-ray disc, whereas DTS-ES Matrix makes use of the identical approach as Dolby Digital EX to extrapolate info from the {surround} channels.

7.1: The spawn of Blu-ray

7.1 Dolby setup
Picture courtesy of Dolby Labs

Simply when folks began getting used to six.1, alongside got here 7.1 together with HD DVD and Blu-ray discs as the brand new must-have {surround} format, primarily supplanting its predecessor. Like 6.1, there are a number of totally different variations of seven.1, all of which add in a second again {surround} speaker.

These {surround} results that when went to only one rear {surround} speaker may now go to two audio system in stereo. The knowledge was additionally “discrete,” which signifies that each speaker bought its personal particular info. This improvement was enabled, partially, by the huge storage potential of Blu-ray.

Those that purchased a devoted again {surround} speaker throughout the shift to six.1 now discovered themselves searching for a brand new, matched pair of again surrounds — sometimes the very same mannequin that they had purchased for the left and proper surrounds.

Dolby provides two totally different 7.1 {surround} variations. Dolby Digital Plus is the “lossy” model. As a substitute of utilizing matrixing, it applies lossy compression to the entire discrete audio channels, which helps to take up much less area on a Blu-ray disc. Dolby TrueHD, alternatively, is lossless. Because of this no sound info has been eliminated throughout compression, and it’s as near the studio grasp as you may get.

DTS additionally has two 7.1 variations, which differ in the identical method as Dolby’s variations. DTS-HD is a lossy 7.1 {surround} format, whereas DTS-Grasp HD is lossless.

It’s vital to notice right here that 7.1-channel {surround} mixes usually are not all the time included on Blu-ray discs. Film studios need to choose to combine for 7.1, they usually don’t all the time achieve this. There are different components concerned, too, with cupboard space being chief amongst them. If a bunch of extras are positioned on a disc, there is probably not area for the extra {surround} info. In lots of circumstances, a 5.1 combine may be expanded to 7.1 by a matrix course of in an A/V receiver. This fashion, these again {surround} audio system get used, even when they don’t get discrete info. That is changing into much less widespread, nonetheless, particularly on the subject of 4K Extremely HD Blu-ray discs, which frequently help a number of seven-channel mixes.

9.1: Professional Logic makes a comeback

In case you’ve been searching for a receiver, you might have seen that many supply a number of totally different variations of Professional Logic processing. Within the trendy Professional Logic household, we now have Professional Logic II, Professional Logic IIx, and Professional Logic IIz. Earlier than we proceed, let’s take a fast have a look at what every of them does.

Professional Logic II

Utilizing the identical matrixed four-channel sound as the unique Professional Logic, Professional Logic II can create a 5.1 {surround} sound combine from a stereo supply. Professional Logic II additionally has one other trick up its sleeve: It may separate the {surround} sign into stereo left and proper channels as an alternative of the unique Professional Logic’s dual-mono presentation. This processing mode is usually used when watching non-HD TV channels with a stereo-only audio combine.

Professional Logic IIx

In case your video supply is introduced in 5.1 {surround} — and your private home theater system helps extra audio system — Professional Logic IIx can take that blend and develop it to six.1 or 7.1. Professional Logic IIx is subdivided into film, music, and sport modes.

Professional Logic IIz

Professional Logic IIz permits the addition of two “entrance top” audio system which can be positioned above and between the primary stereo audio system. This type of matrix processing goals so as to add extra depth and area to a soundtrack by outputting sounds from a complete new location within the room. Since IIz processing may be engaged with a 7.1 soundtrack, the ensuing format could possibly be referred to as 9.1.

Regardless of the addition of those top channels, Professional Logic IIz doesn’t allow a real 3D placement of sounds. To allow that, you’ll want Dolby Atmos or DTS:X, which we describe under.

What about 7.2, 9.2, or 11.2?

As we talked about beforehand, the “.1” in 5.1, 7.1, and so on., refers back to the LFE (low-frequency results) channel in a {surround} soundtrack, which is dealt with by a subwoofer. Including “.2” merely signifies that a receiver has two subwoofer outputs as an alternative of 1. Each connections output the identical info since, so far as Dolby and DTS are involved, there is just one subwoofer monitor. Since A/V receiver producers needed to market the extra subwoofer output, the notion of utilizing “.2” was adopted.

For most individuals, a single subwoofer will present ample low-end bass and rumble. Nevertheless, including a second sub can improve this impact, particularly in bigger media rooms. Try our subwoofer placement information to study why a second sub may be best for you.

Audyssey DSX and DSX 2

Audyssey, an organization greatest identified for its auto-calibration software program present in a lot of at this time’s A/V receivers, has its personal {surround} resolution referred to as Audyssey DSX. DSX additionally permits for added audio system past the core 5.1 and seven.1 {surround} codecs, upmixing 5.1 and seven.1 indicators so as to add extra channels. With the addition of entrance width and entrance top channels on prime of a 7.1 system, Audyssey permits for 11.1 channels of {surround} sound.

There’s additionally Audyssey DSX 2, which provides upmixing of stereo indicators to {surround} sound. With the arrival of object-based 3D codecs like Dolby Atmos and DTS:X in recent times, nonetheless, Audyssey has seen a decline.

3D/object-based {surround} sound

image courtesy Dolby Labs

                        picture courtesy Dolby Labs

As we talked about earlier, the newest and biggest improvement in {surround} sound is named “object-based” or “3D” {surround}. For viewers, “3D” provides one of the best description of this expertise due to its means to make sounds really feel as if they’re transferring by means of area. For example, you may hear a helicopter take off from in entrance of you, hover over your head, after which disappear into the gap behind you.

“Object-based,” alternatively, is the moniker most well-liked by the sound professionals who create these 3D soundtracks as a result of it describes their means to maneuver a single sound-producing object (like a helicopter) anyplace in 3D area.

This immersive hemisphere of sound is made potential by including discrete channels for ceiling-mounted or ceiling-facing audio system in A/V receivers at residence.

As a result of these channels not must extrapolate their indicators from audio operating to different audio system as they did with Professional Logic IIz 7.1, they get their very own quantity. A 5.1.2 system, for instance, would function the normal 5 channels and a subwoofer, however it will additionally function two extra audio system including top info in stereo on the entrance. A 5.1.4 system would add 4 extra top channels to five.1, together with two on the entrance, two on the rear, and so forth.

Dolby Atmos

This shouldn’t come as a shock after studying the remainder of this text, however Dolby is the present chief in object-based {surround} sound expertise. We’ve been over Atmos’ bid to revolutionize the movie show expertise, however what about residence theaters?

Atmos within the residence

Onkyo 7.2-channel 4K AV Dolby Atmos receiver

Atmos debuted on suitable A/V receivers in 2015, however in a way more restricted capability than the skilled format. As talked about above, the most typical configurations are 5.1.2 or 5.1.4, which add two and 4 top audio system to a conventional 5.1 {surround} setup respectively, although Dolby helps a lot bigger configurations. Atmos took off comparatively shortly, and most A/V receivers above the low-end vary of the spectrum now help the format. The truth is, each receiver on the record of our favourite A/V receivers helps Atmos, even fashions priced at $500 or much less.

In 2015, Yamaha launched the primary Atmos-capable soundbar, the YSP-5600, which makes use of up-firing drivers to bounce hold forth the ceiling.  Since then, soundbar producers have totally embraced Dolby Atmos. Some obtain the Atmos impact utilizing devoted wi-fi {surround} audio system with up-firing drivers to enrich the entrance audio system within the bar. Others use a method generally known as virtualized Dolby Atmos to convincingly simulate the Atmos impact utilizing fewer audio system.

Some TVs, like LG’s line of very good OLED TVs, declare Dolby Atmos help by means of the TV’s built-in audio system. As a result of Dolby Atmos may be calibrated for as few as two channels, we suppose that is technically correct. Nevertheless, patrons needs to be conscious that two-channel Atmos won’t ever sound pretty much as good as discrete 5.1.2 or higher Atmos.

Films with Dolby Atmos soundtracks at the moment are quite common on Blu-ray and Extremely HD Blu-ray discs. Furthermore, streaming websites like Netflix, Vudu, Amazon Prime Video, Disney+, and Apple TV+ all supply a collection of Atmos motion pictures and exhibits. Atmos is even beginning to seem in some stay broadcasts. Latest examples embrace the 2018 Winter Olympics, the NHRA’s stay drag-racing occasions, and even a couple of music festivals.

One factor to bear in mind with Dolby Atmos: It’s a finicky beast. So as to hear Dolby Atmos sound, each a part of your private home theater system — from the supply to the audio system — must help it. Right here’s our full information to getting nice Dolby Atmos sound.

Dolby Atmos Music

Although nonetheless in its early levels, Dolby Labs has been working with main document labels and streaming companies to develop the usage of Dolby Atmos expertise for music manufacturing. The idea is straightforward: Dolby Atmos Music makes use of all the identical object-oriented 3D audio instruments because the film soundtrack model however places them within the arms {of professional} music producers.

The result’s immersive music that goes nicely past what conventional two-channel stereo and even quadraphonic sound can obtain. Sadly, Dolby Atmos Music may be very restricted in the mean time. The one option to hear it utilizing a Dolby Atmos-equipped residence theater is to purchase one of many only a few Blu-ray discs that include a Dolby Atmos Music combine, just like the not too long ago remastered and rereleased Kick by INXS.

Amazon Music HD not too long ago turned the primary music streaming service to supply Dolby Atmos Music tracks, however the one manner you may hear them is through Amazon’s Echo Studio 3D sensible speaker.

In a couple of choose golf equipment, Dolby Atmos Music is being utilized by DJs and different stay performers to provide an immersive music surroundings for dance flooring.

Hopefully, Dolby will quickly open the floodgates on Dolby Atmos Music and discover extra methods for people to expertise it.

It’s value noting that Sony additionally has a 3D immersive music format generally known as Sony 360 Actuality Audio that competes with Dolby Atmos Music. It too may be discovered on some streaming companies, however as with Atmos Music, the units wanted to listen to it are restricted to just some choices for the second.


Simply because it does with different kinds of {surround} sound, DTS has its personal model of object-based audio, DTS:X, which was unveiled in 2015. DTS:X goals to be extra versatile and accessible than Atmos, making use of preexisting speaker layouts in theaters and supporting as much as 32 totally different speaker configurations within the residence.

Whereas DTS:X was beforehand tacked on in updates for Atmos-enabled A/V receivers, it’s now accessible with newer A/V receivers proper out of the field. Firms like Lionsgate and Paramount supply residence releases in DTS:X, however its lack of widespread adoption on disc-based media — and 0 adoption amongst streaming companies — is its largest limiting issue.

DTS Digital:X

DTS additionally acknowledges that not all film lovers have the area or the time to place collectively an object-based sound system. Analysis gathered by DTS confirmed that lower than 30% of consumers really join top audio system to their programs, and fewer than 50% even hassle connecting {surround} audio system.

To that finish, the corporate developed DTS Digital:X, which employs digital sign processing (DSP) in an effort to supply the identical spatial cues {that a} conventional DTS:X system would offer, however over a smaller variety of audio system, even if you happen to’ve solely bought two. This expertise first rolled out in soundbars, which is smart, as they typically solely embrace a separate subwoofer and perhaps a pair of satellite tv for pc audio system at most. Since then, firms like Denon and Marantz have added help for DTS Digital:X to their receivers, whereas Sony has its personal digital {surround} soundbar that reads DTS:X and Atmos mixes.

Technically talking, “virtualized” Dolby Atmos and DTS Digital:X are very comparable; nonetheless, Dolby prefers to not distinguish between Dolby Atmos implementations. So far as it’s involved, Atmos is Atmos, whether or not it’s virtualized by means of two, three, or 5 channels, or totally baked utilizing a discrete 5.1.2 or higher speaker system.


Although you might not have heard of Auro-3D till now, it was on the scene nicely earlier than DTS:X or Atmos appeared. The expertise was introduced in 2006 to be used in theaters, however wasn’t accessible for residence theater programs. Due to Denon and Marantz pushing it by means of as a firmware improve, now you can use it with your private home audio system although it’s important to pay for it.

Regardless of obvious likeness to Dolby Atmos, Auro-3D creates a surround-sound expertise by means of a three-tiered sound system. A number of audio system actually showcase this sort of layered sound. We advocate eleven audio system to get probably the most out of the sound, making Auro-3D the most costly setup you may recreate at residence. As a result of Auro-3D normally makes use of a single overhead channel, its speaker configurations aren’t optimum when used with Dolby Atmos sound.

We haven’t seen a development in reputation for Auro-3D in the USA, however contemplating its pervasive utilization in Europe and Japan, it’s solely a matter of time.

In sum …

Whereas it could look like issues are getting extra difficult, studio-quality residence theater sound is extra accessible than ever. Improvements in “object-based” or “3D” {surround} sound, mixed with the addition of devoted audio system to the usual 5.1 setup have upped the ante, certain — however you don’t should be a sound engineer or audiophile to create an immersive expertise at residence. A little bit little bit of analysis goes a great distance, so preserve this information helpful as you construct your setup and you should not have any bother determining what’s best for you. Completely satisfied viewing/listening!

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