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Understanding surround sound formats

Dave Bar worked for Crutchfield from 1981 until his retirement in 2016. After a 23-year stint in the sales department, he joined the home A/V writing staff. Dave's expertise and good humor will be sorely missed.

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Tara W. has worked for Crutchfield since 2004. She writes about whole-house music and video gear, and works on Crutchfield's video team.

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Confused about surround sound formats? Here's a guide to clear things up. 

Let's start by defining some frequently used terms. You can also take a look at our surround formats chart

5.1: 5.1 surround sound is the most common format. It includes a total of six channels — five full-bandwidth channels with 3-20,000 Hz frequency range for front left and right, center, and left and right surrounds, plus one "low frequency effects" (LFE) subwoofer channel for frequencies from 3-120 Hz.

6.1 and 7.1 surround sound systems are also available, and simply add another full-bandwidth channel to the mix. (To see how the speakers are arranged in a multichannel surround system, check out the diagrams in our guide to home theater speaker placement.)

Discrete: Some channels are considered "discrete" — that means that the sound information contained in each of the available channels is distinct and independent from the others.

Matrixed: Other channels are considered "matrixed" — that means that the sound information in those channels is extrapolated from information in other channels. Though you'll notice more precise surround effects from discrete channels, you can still expect engaging sound from matrixed channels.

Lossless: Some surround formats are compressed so that they're small enough to be stored or transmitted — on a DVD, for example, or in a satellite TV broadcast. But higher-capacity Blu-ray Discs™ can hold lossless surround soundtracks that are identical to the original studio recording. The higher quality of these formats makes for more detailed audio.

5.1-channel surround

There are two main formats that deliver surround sound for 5.1-channel systems.

Dolby Digital
Unlike earlier forms of surround sound, Dolby Digital 5.1-channel audio is a discrete multichannel surround sound system. With six discrete channels, sounds can be placed very precisely, for improved dialogue clarity, imaging, spaciousness, and realism. You also get a dedicated subwoofer channel, for plenty of deep bass.

How Dolby Digital works

Like Dolby Digital, DTS® provides 5.1 channels of digital audio. However, DTS uses less compression than Dolby Digital. As a result, some say that the sound produced by DTS is slightly more accurate than the sound produced by Dolby Digital. While most audio/video receivers will have both Dolby Digital and DTS, fewer discs and video games are encoded with DTS, compared to the number encoded with Dolby Digital.

6.1-channel surround

A 6.1-channel system uses a single rear surround speaker to deliver an even more enveloping surround effect.

DTS-ES™ adds a discrete, full-bandwidth back surround channel.

Dolby Digital EX and THX Surround EX
These formats add a matrixed back surround channel for a 6.1-channel speaker system.

Many DVDs are encoded for Dolby Digital EX, and have the extra channel of surround information ready to go. If you're playing a regular Dolby Digital 5.1-channel DVD, a Dolby Digital EX or THX Surround EX™ decoder will simulate 6.1-channel surround by processing the audio information in the discrete surround channels and sending the matrixed audio info to your back surround speaker.

How DTS-ES 6.1 works

7.1-channel surround

Blu-ray players support 7.1 audio formats and high-quality, lossless surround sound.

While your high-def disc player and receiver may be able to decode these new surround sound formats, not all discs you play will take advantage of them. Be sure to check out the details on the Blu-ray discs you watch to see which audio format they use. 

Blu-ray Logo

Lossless surround sound formats
Dolby TrueHD and DTS-HD™ Master Audio, offer up to 7.1 discrete channels of lossless audio. Along with adding two extra rear channels to the standard Dolby Digital and DTS formats, Dolby TrueHD and DTS-HD Master Audio discs are encoded with more audio information per channel. In fact, it's identical to the movie studio's original master. That means the improved directionality and more precise effects makes it even closer to the experience of being in a movie theater.

Additional discrete 7.1-channel surround formats
You may find that some Blu-ray discs are also encoded with other discrete 7.1-channel surround formats. Dolby Laboratories and DTS developed Dolby Digital Plus and DTS-HD (High Resolution), respectively. These formats deliver 7.1 independent channels of sound. They provide more detailed surround effects than 5.1 Dolby Digital and DTS, though they aren't lossless like Dolby TrueHD and DTS-HD Master Audio. Receivers that support lossless 7.1-channel formats will also support Dolby Digital Plus and DTS-HD (High Resolution).

"Height" channels for a taller soundstage

A few receivers offer a newer surround sound format called Dolby Pro Logic IIz. It adds two "height" channels to your front soundstage. These speakers typically mount on the wall above your existing front left and right speakers.

A receiver with Pro Logic IIz can divvy up the front soundstage audio. It sends directional sounds — like a car racing by — to your regular front speakers, and non-directional sounds — like the roar of a crowd at a stadium — to the height channels. The result is a larger, deeper front soundstage, and a more immersive experience.

Dolby Atmos® adds overhead sound to the mix

This innovative surround sound format uses in-ceiling or Dolby-enabled upward-firing speakers to project sound from above your seating positions. Receivers with Dolby Atmos capability can create an incredibly immersive listening experience by placing sounds more accurately in the room than conventional setups.

Dolby Atmos soundtracks use two distinct sound fields to achieve these effects. The "bed" consists of stationary sounds such as background sound and music. "Objects" are assigned specific locations in the three-dimensional listening space, which the in-ceiling or Dolby Atmos enabled "top" speakers help bring to life with depth and realism.

Matrixed surround decoding for older sources

If you use a stereo analog connection to your receiver, or are connecting older equipment like a VCR, your receiver may employ one of these types of processing to decode the signal. Dolby Pro Logic II includes two independent full-bandwidth front channels, three matrixed surround channels, and a dedicated low-frequency channel for your subwoofer. Many recent home theater receivers also offer Pro Logic IIx processing, which can turn the same sources into even more enveloping 7.1-channel sound.

DTS Neo:6 is essentially identical to Pro Logic II — it's simply the processing DTS came up with to deliver 5.1 or 6.1 channels of sound from a two-channel stereo source.

"My receiver has other surround formats, too"

Sometimes manufacturers will put their own special processing in a receiver, often called Digital Signal Processing (DSP), in addition to the formats described above. Many home theater receivers use Digital Signal Processing to create soundfields — simulated acoustic environments, like a concert hall or stadium — and for precise steering of multichannel soundtrack information. This feature may go by different names, depending on the manufacturer. Check your owner's manual for details about your receiver's DSP modes.

Last updated May 06, 2016
  • Lyle from Calif.

    Posted on 5/28/2015 3:56:15 AM

    To experience Dolby Atmos, would one need to buy an Atmos system, as well as convert existing movies / music to Atmos format?

  • David Brown from Crutchfield

    Posted on 5/28/2015 9:31:43 AM

    Hi Lyle,

    To experience Dolby Atmos, you'll need a Blu-ray player, an Atmos capable home theater receiver, and "height" speakers added to a conventional surround sound system. These speakers can be in-ceiling speakers or special Dolby enabled speakers that sit atop your front speakers. Dolby enabled speakers have drivers that point upward to reflect sound off of your ceiling.

    There are several Blu-ray titles available with Atmos soundtracks. An Atmos capable home theater receiver can also upconvert standard surround sound formats to Atmos.

    We offer several receivers with Atmos capability, as well as lots of in-ceiling speakers and some Dolby enable speakers, too. Feel free to call, email, or chat if you need help choosing gear or have more questions.

  • Justin from 97138

    Posted on 6/13/2015 10:35:26 PM

    I can see and understand the want for the highest audio format. But when it comes to Dolby Atmos, I don't believe it's worth the has'll on investing in a receiver unless you own or rent a home with an extremely large living room. But in a standard apartment I just put the SL & SR up towards the ceiling facing down at an angel and when something fly's over the top it sounds like it's going right over your head.

  • David havens from Conway Arkansas

    Posted on 7/4/2015 2:19:52 AM

    I have a receiver that has neo 6. I have a front left right and center speaker. By moving the neo 6 spread to my left and right speakers am I making my center speaker useless? I assume that neo 6 is to get more detailed sound from 2 channel recording such as an older cd? Thanks

  • David Brown from Crutchfield

    Posted on 7/14/2015 10:11:41 AM

    Hi David, DTS Neo:6 takes two-channel source material, such as a music track from a CD, and essentially re-configures it for 5.1-channel audio. By not utilizing your center channel speaker, you're not really giving the software the chance to do what it does. So I wouldn't expect you to gain any improvement in sound quality from a CD.

  • Nick from Chicago

    Posted on 8/21/2015 11:11:36 AM

    Thanks for the article. Its good info indeed. I do however have a question that i'm finding hard to find the answer too. Maybe because it's just a given, Ha. I'm planning on building a 5.1 theater and will probably only ever have 5.1. I will of course be using it as a home theater, I also love stereo Music. I guess my question is; if I only have 5.1 will I still be able to play in its full quality the Lossless formats (Dolby TrueHD and DTS-HDT Master Audio) for movies and music?? Will I still be getting this quality (with a compatible receiver of course) using only a 5.1 setup? I understand that I will be lacking 2 channels of sound but will I still be getting the best out of the 5.1 I can get? Thanks again!

  • David Brown from Crutchfield

    Posted on 8/21/2015 1:05:10 PM

    Nick, Whether you have a 5.1 or 7.1 system, you'll be able to get uncompressed audio from Dolby TrueHD and DTS Master Audio Blu-ray discs, assuming you have a compatible player and receiver. If you connect your Blu-ray player via HDMI to the receiver, the receiver will do the necessary processing of the signal to output audio to the appropriate channels.

  • Tom from Eagan, MN

    Posted on 12/11/2015 2:50:26 PM

    Great article. Helped clear things up for me. I found the article because I've run across a problem recently with two Blu-Ray discs with Dolby Atmos. I have a Sony STR-DH500 receiver that is Dolby Digital and DTS capable. The Blu-Ray with Atmos did not offer a 5.1 option in the audio set up and I ended up getting two channel stereo output. Needless to say it was a disappointing audio experience. I don't want to upgrade to a new receiver at this time. How should I be setting the DVD audio options on the disc or my receiver to get 5.1 (or should I just avoid Atmos Blu-Ray and stick with Dolby Digital or DTS DVDs?).

  • David Brown from Crutchfield

    Posted on 12/11/2015 3:43:48 PM

    Hi Tom, As I understand it, all discs with Dolby Atmos soundtracks should feature more conventional flavors of Dolby surround sound as well. If you're connecting the devices via HDMI, I would think you should be able to get a 5.1-channel signal. Make sure your Blu-ray player is set to "bitstream" output in the settings menu. If you purchased either your Blu-ray player or your receiver from us, I encourage you to call our tech support team. They should be able to help, or at least give you a definitive answer about why you can't get anything but stereo. Good luck!

  • Jesus from Miami

    Posted on 2/1/2016 3:46:35 PM

    Hi David. Excellent article. I would like to ask you what exactly is DTS Neo 2:5. I have a Samsung TV (UN55UH6830), a Samsung Blu-ray (BDF5700) and a Samsung Home Theater System (HT-J5500W). The setup is: DirecTV+AppleTV+Blu-Ray (HDMIs) > TV > Home Theater (HDMI ARC). I still cannot get Dolby Digital from my DirecTV box. The only options are PCM and DTS Neo 2:5. So, what is DTS Neo 2:5? It is the same as DTS 5.1? If not, what are the differences between them? Thanks

  • David Brown from Crutchfield

    Posted on 2/2/2016 11:14:39 AM

    Hi Jesus, I was not familiar with DTS Neo 2.5, but I did a little research on it. It is a "matrix" version of DTS that is used to deliver a multi-channel signal to a receiver for decoding and playback with your surround system. If your DirecTV box outputs Neo 2.5, your Samsung home theater system (which is DTS compatible) should be able to decode it and send sound to all of your speakers. It's not quite the same as a discrete Dolby or DTS 5.1-channel signal, but I'd give it a try. If you purchased any of your gear from us and need more help, give our tech support folks a call.

  • Martin Eastham from Cedar Rapids, Iowa

    Posted on 2/25/2016 2:41:26 PM

    I currently have 7.1 setup in my living room. In order to upgrade to Atmos, what would I need? I could easily add another pair of speakers in the front of my viewing area. They would be above my L/R main speakers. Would this work, or would they need to be in the ceiling, more to the center of the living room? Is Atmos the same thing as 9.1 sound? I realize I would also need to upgrade my Home Theatre receiver.

  • David Brown from Crutchfield

    Posted on 2/25/2016 4:05:32 PM

    Martin, It sounds like a pair of Atmos enabled speakers would be perfect for your setup. These are special add-on speakers that can rest on top of your existing speakers so the drivers point toward the ceiling. You could add two of the speakers to the front mains for a 7.1.2 Atmos system. With a pair of these speakers and a nine-channel Atmos capable receiver, you'll have everything you need (assuming you already have a Blu-ray player). That will be a killer system!

  • Gene Anthony Jurick from Millville

    Posted on 2/25/2016 9:12:51 PM

    David, Excellent article and information. I just have one question. When listening to a HD feed I'm not sure of the best setting depending on what I'm watching? For example I am currently watching a hockey game and 7.1 is displayed. If I switch to the TV Sports setting the background sound is more detailed however, I lose the fullness 7.1 provides. I have found several articles explaining what the different settings provide, however, I have yet to find information on which format is best for whatever you are watching.

  • David Brown from Crutchfield

    Posted on 2/26/2016 9:02:32 AM

    Gene, It's really all about personal preference. Most receivers offer their own surround listening modes, which are designed for specific types of content (sports, action movies, video games, etc.). Personally, I've found "sports" settings to be pretty good at providing enveloping crowd noise while also giving the announcers voices more clarity (though sometimes I wish there was a way to mute certain announcers!).

    The formats themselves are usually proprietary to the receiver manufacturer — they're just taking the Dolby signal from your cable/satellite box and adding in their own digital signal processing. Experiment and see what sounds best to you.

  • Jax from Brooklyn

    Posted on 3/31/2016 12:49:15 PM

    Thank you David, this was very helpful. However, I have some additional questions. I am looking to get an amp, but am not sure if I should go stereo (Peachtree Audio nova220SE) or go for an av receiver. I watch a good amount of movies via netflix, hbo, and amazon prime, but also enjoy good stereo music. I don't currently have or plan to get additional input devices beyond what I have--an apple tv. I have only 2 bookshelf speakers (kef ls50) and am not looking to get more at the time since my apartment is rather small and I don't want to run cables everywhere (I rent). The nova has much better sound for music, but how does it handle movies? Can it decode the lossless formats? How does it compare to a av amp in this regard? Do DTS or Dolby DIgital or Atmos have any value in a 2 channel sound system? You mentioned that Dolby TrueHD and DTS-HDT Master Audio, offer UP TO 7.1 discrete channels of lossless audio--does this mean that this applies to a mere 2 channels as well? My apologies for the swarm of questions. Please let me know if I am looking at this all wrong. Thanks.

  • David Brown from Crutchfield

    Posted on 3/31/2016 4:05:51 PM

    Jax, For your situation, the Peachtree amp makes a lot of sense. If you're not planning on surround sound, then a high-quality integrated amp and bookshelf speakers is a great setup for TV, movies, and music.

    Depending on which model Apple TV you have, you may be able to connect it to the Peachtree and get stereo sound from video content. We also sell a DAC that can convert Dolby signals to analog stereo.

    Another option would be to connect the Apple TV to your TV, then run an optical cable from the TV to the Peachtree.

    I've forwarded your question to our sales advisors. Someone will email you to follow up. Or feel free to give us a call.

  • Shrini from fairfax

    Posted on 5/4/2016 5:52:18 PM

    Hi. I have question. If I have a 5.1.2 set up and play a stereo content (for example stream tracks from my mobile over bluetooth via my av receiver) will my surround speakers, center channel and height speakers produce sound or only my front left and right channel produce sound for stereo content? The other question related to this is, if I have atmos height speakers set up will they draw power when a non-atmos content is playing or will some sound come out of height speakers when listening to audio tracks?

  • David Brown from Crutchfield

    Posted on 5/5/2016 8:39:47 AM

    Hi Shrini, Typically music tracks only play through your stereo front/main speakers. However, most receivers offer surround modes that will take a stereo track and convert it for surround, thus playing music from all speakers. Dolby Pro Logic IIx is a common format built into most receivers for this purpose.

    Most Atmos capable receivers have a feature called Dolby Surround, which will take non-Atmos audio and convert it to utilize all speakers in your 5.1.2 configuration (or whatever Atmos setup you have). I know this works with Blu-ray discs, but I'm not sure it works with music streamed from a smartphone. I'm working on finding out now. I'll update this post when I have an answer for you.

    UPDATE: I checked with our Yamaha rep, who is a whiz with all this stuff. He says that Yamaha receivers with Atmos capability can do this. They have a DSP function that will allow you to hear your music through all speakers in a 5.1.2 system. The music won't technically be "Atmos" but you'll be able to hear it through all speakers, including the height speakers.

    If you have more questions, feel free to give us a call!

  • Wayne from Culpeper

    Posted on 5/12/2016 12:15:06 AM

    I know this sounds like heresy to audio buffs, but I have "old" ears which have been abused through time. I cannot understand the dialogue in some TV shows which play the background music/sound effects louder than the dialogue. Are there sound systems for TV which will allow one to INDEPENDENTLY turn down the music/sound effects and turn up the volume on the dialogue only?

  • David Brown from Crutchfield

    Posted on 5/12/2016 8:50:54 AM

    Wayne, your comment is a common one among our customers. Fortunately, we have lots of solutions. For instance, many sound bars offer dialogue enhancement features, which can give more clarity to voices. The best option would be a home theater receiver with 3 to 5 speakers. Yamaha's new receivers, like the RX-V481, offer independent dialogue level adjustment.

    Our advisors can help you sort through your options. I've forwarded your question to them. Someone will email you to offer more specific guidance based on your needs.

  • Tyler from Hillsboro

    Posted on 8/9/2016 2:22:01 AM

    I just purchased a new Yamaha Aventage Atmos receiver and I run a standard 6.1 setup. The manual for my previous Yamaha 7.2 receiver specifically explained how to setup a 6.1 speaker system. The manual for the new receiver simply jumps from 5.1 to 7.1. Is the 6.1 format supported in the new Atmos receivers?

  • David Brown from Crutchfield

    Posted on 8/9/2016 4:22:58 PM

    Tyler, it's my understanding that Yamaha's latest receivers with Dolby Atmos do support 6.1-channel formats. I'm not sure which model you have, but the manual for the AVENTAGE RX-A760 refers to support for DTS-ES, which is a 6.1-channel matrix format.

    If you're having trouble and you purchased your receiver from us, I recommend you call our tech support team. They can help you get it set up properly.

  • Rick from Schaumburg

    Posted on 8/16/2016 2:59:58 PM

    Crutchfield is the best!. I have a new Denon atmost capable AVR that I was interested in adding a couple of Atmos add on speakers to. I currently was running 7.1, and no speaker terminals were marked atmos or height nor were there any empty ones remaining. I suspected I had to go back to 5.1 , but still was not sure which terminals to use. I contacted Denon support and the next day they said to look at page 54 in your manual. I emailed back to say there was no manual, just a quick set up guide, and I could not find a manual for my latest model online. Two days later, they emailed back and said check the attachment, of which there was none. I said forget it, emailed Crutchfieds and within 10 minutes they had a simple, clear answer for me. Very impressive. Thank you.

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