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Lead image

Understanding Dolby and DTS surround sound formats

For movies and music

C

hanges in audio/video technology have given rise to a lot of different surround sound formats over the years. The latest formats have a lot to offer in terms of realism and detail. But today's home theater receivers can still decode a lot of the older formats, just in case you wanted to hook up your old VCR or LaserDisc player.

Surround sound at home: a little history

In the beginning, there was VHS. Now, instead of tapes, we have discs, digital TV broadcasts, and streaming content. As home media evolved, audio engineers gained the ability to make great improvements to surround sound.

timeline

Early forms of surround sound didn't include discrete audio information for multiple channels. Instead, they extrapolated surround sound information from a two-channel (stereo) signal. These "matrixed" channels were played back through four speakers at first, and eventually five speakers and a subwoofer.

More advanced surround sound formats encode discrete sounds on different channels. The results are clearer dialogue and improved imaging, spaciousness, and overall realism.

About the numbers

By now, you've probably seen numbers like "5.1" and "7.1", and you might be wondering what they mean. This shorthand describes the number of channels of audio information that surround sound formats support.

In the case of a 5.1-channel format, "5.1" refers to five separate audio channels, plus an LFE (low-frequency effects) or subwoofer channel (the ".1"). 

The newest surround sound formats

Dolby Atmos adds overhead sound to the mix

immersive-listening

Dolby Atmos can create an incredibly immersive listening experience by placing sounds more accurately in space.

Dolby Atmos started making its way into home theaters a few years ago. Now it's pretty much standard in receivers with seven or more channels. This "object-based" format assigns audio "objects" to specific locations in your listening area to correspond to where they'd occur naturally in space. This adds a three-dimensional feel to the two-dimensional images on your screen.

Atmos Speaker Layout

Dolby Atmos achieves multi-dimensional surround sound by adding overhead speakers to a regular 5.1- or 7.1-channel surround sound system.

The overhead or up-firing speakers used in Atmos setups add a third number to the system configuration shorthand. For example, a five-channel Dolby Atmos system with two overhead speakers is a 5.1.2 system.

Setting up an Atmos system at home

Here's a breakdown of what you'll need to experience Atmos at home:

  • A Dolby Atmos capable receiver
  • At minimum, a five-speaker surround sound setup, plus two additional overhead or up-firing speakers, plus a subwoofer
  • Content encoded with Dolby Atmos (some Blu-ray discs, streaming content, and video games)

Receivers with Atmos decoding have at least seven channels. More channels will get you more Atmos configuration options. For example, with a nine-channel receiver, you can set up a 5.1.4 or 7.1.2 system.

DTS:X: a flexible object-based surround sound format

As with Dolby Atmos, movie soundtracks encoded with DTS:X place sounds where they would naturally occur in space. DTS:X is also interactive. Some DTS:X encoded content lets you tweak dialogue levels, so you can hear voices better over background effects.

Unlike Atmos, DTS:X doesn't require any special kind of speaker layout, so it works with or without overhead speakers. Of course, the sound is going to be more lifelike with the overhead speakers, but you can also get impressively lifelike sound from a standard 5.1- or 7.1-channel setup.

Are overhead speakers really worth the trouble?

If you ask me, they are. If you set up an Atmos system with overhead speakers, it's also going to serve as a great DTS:X system. Some of your video content will be encoded with Atmos, some with DTS:X, and sometimes you won't have either of those options.

But if your receiver can decode Atmos and DTS:X, it also supports two additional formats: Dolby Surround and DTS:Neural X. These "post-processing" formats allow your receiver to "up-mix" other formats so you can get overhead effects from any content you choose.

5.1 and 7.1 surround sound formats

5.1 surround sound

5.1: a great place to start

5.1 home theater systems are still more common than larger speaker setups. They're the most affordable, and often the most practical multi-speaker configurations. A lot of us simply don't have room for more than five speakers. And 5.1 surround sound is plenty engaging.

Setting up your own 5.1 system

Here's what you need to get 5.1 surround sound in your living room:

  • A home theater receiver with at least five channels
  • Five speakers (Front Left and Right, Center, and Surround Left and Right), plus a subwoofer
  • Content encoded with 5.1-channel surround sound information (DVDs, Blu-rays, cable and over-the-air TV, streaming media, and video games)

Even if you are planning to set up a five-channel home theater system, we'd still recommend getting a seven-channel receiver. It'll give you some advantages, like the ability to hook up speakers for music outside or in another room. Plus it allows for an easy future upgrade to 7.1 surround sound or a 5.1.2 Atmos system.

5.1-channel formats

Dolby Digital

  • The original discrete multi-channel format
  • Improved clarity and realism over earlier formats
  • Uses compression to fit full-length movies with discrete surround sound information onto a disc 

DTS

  • Uses less compression than Dolby Digital; some say it is slightly more accurate
  • Not as widely available as Dolby Digital

Dolby Pro Logic II

  • Decodes stereo recordings and converts them to 5.1-channel surround sound

DTS Neo:6

  • Like Dolby Pro Logic II; uses up-mixing to deliver 5.1-channel sound from two-channel sources

7.1: a more enveloping surround sound experience

7.1 surround sound

7.1-channel surround sound adds two additional rear surround speakers to the standard 5.1 speaker configuration. Blu-ray discs have room for more audio information than DVDs, so they can be encoded with 7.1 audio formats for high-quality, lossless surround sound.

Setting up your own 7.1 system

Here's what you need to get 7.1 surround sound in your living room:

  • A home theater receiver with at least seven channels
  • Seven speakers (Front Left and Right, Center, Surround Left and Right, and Surround Back Left and Right), plus a subwoofer
  • Content encoded with 7.1 surround sound information (some Blu-rays, streaming media, and video games)

7.1-channel formats

Dolby TrueHD

  • Offers up to 7.1 channels of lossless (uncompressed) audio
  • Identical to the movie studio's original master recording
  • More precise effects

DTS-HD Master Audio

  • Like Dolby TrueHD; provides 7.1 discrete channels of lossless audio
  • Identical to the original movie studio recording

Dolby Pro Logic IIx

  • Like Dolby Pro Logic II; uses special processing to up-mix two- or five-channel audio signals to 7.1 surround sound

Dolby Digital Plus

  • Provides more detailed sound effects than Dolby Digital 5.1, though it isn't lossless like Dolby TrueHD

DTS-HD

  • More detailed than the original 5.1 DTS, but not lossless like DTS-HD Master

Less common surround sound formats

9.1 and beyond

9.1 speaker layout

A receiver with nine or more channels opens the door to some serious surround sound possibilities. These receivers incorporate two extra channels to add a "height" layer to a 7.1-channel speaker layout. These height speakers (not to be confused with Dolby Atmos overhead speakers) typically go on the wall above your existing front speakers.

Setting up your own 9.1 system

Here's what you need to get 9.1-channel surround sound in your living room:

  • A home theater receiver with at least nine channels
  • Nine speakers (Front Right and Left, Center, Surround Right and Left, Surround Back Right and Left, and Front Height Right and Left), plus a subwoofer

Currently, you won't find a lot of content natively encoded with 9.1 discrete channels of audio information. But a nine-channel receiver is capable of up-mixing different surround sound formats to 9.1 for greater realism.

9.1-channel formats

Dolby Pro Logic IIz

  • Can up-mix two-channel and multichannel surround sound sources to 9.1 with front height effects
  • Also works with 7.1 setups, sacrificing surround back speakers in favor of front height speakers

Auro 3D

Auro 3D configurations start with a standard 5.1 speaker layout, and add a second layer of speakers above, called a “height layer”.

Auro-3D

  • A unique format that adds a height layer consisting of four speakers to a standard 5.1 speaker layout
  • Additional height speakers are placed above the front right and left and surround right and left speakers, respectively
  • Built into some current Denon and Marantz receivers with nine or more channels; available as a paid upgrade to older models

You'll find Auro-3D encoded on some Blu-ray discs, and Auro-matic up-mixing lets you take advantage of Auro-3D's height layer with any content you choose.

Auro-3D speaker setups don’t readily lend themselves to Dolby Atmos since Atmos doesn’t make use of surround height speakers. But there are potential workarounds. Some receivers will allow you to use rear height speakers instead of surround height speakers for a 9.1 Auro-3D configuration that acts as a 5.1.4 system when you watch Atmos encoded content.

If you want a receiver that supports both formats with one speaker layout, be sure to do your research. The owner’s manual will tell you what all the possible configurations are.

11-channel receivers: great for Dolby Atmos, DTS:X, or Auro-3D

For the serious home theater enthusiast, an 11-channel receiver will let you set up an impressive 7.1.4 or 9.1.2 Dolby Atmos system. Many people find these configurations ideal for DTS:X as well.

If you're going the Auro-3D route, having eleven channels at your disposal will give you an even more dynamic surround sound experience. The Auro 10.1 configuration adds a tenth speaker, directly above the listening position, known as the "Voice of God". And Auro 11.1 adds a front height center channel speaker to the 10.1 configuration.

13 channels of immersive home theater

Currently there's just one 13-channel receiver on the market, and it's pretty impressive. Denon's AVR-X8500H gives you the most surround sound configuration options from a single A/V component.

This receiver supports 7.1.6 or 9.1.4 Atmos configurations, as well as Auro 13.1, which adds left and right surround back channels to the Auro 11.1 setup.

Have questions? We're here to help

If you're looking for help setting up your own surround sound system, feel free to get in touch with us. Our advisors can offer great advice on receivers and speakers and answer any questions you have.

  • Charles Summers from Kirksville MO.

    Posted on 9/18/2021

    I have a Pioneer VSX LX 103 AVR with the Def Tech 9020 front speakers, and I just added the toppers , the A90's. The speakers and toppers all bought from Crutchfield. Great sound and very tight bass from the 9020's. I got the toppers because we didn't want to put anything in our ceiling, or at least the wife didn't. I was wondering what the best setting for the A90's would be. I have a choice on the Pioneer front high, top front, top front, top middle, rear high, Dolby speaker front or Dolby speaker Surround. I also have Def Tech center speaker and two Bose bookshelf surround speakers. Thank you, sorry about the length of this.

    Commenter image

    Kramer Crane from Crutchfield

    on 9/20/2021

    Thanks so much for reaching out, Charles. I recommend selecting "Dolby Enabled Speakers (Front)" during the speaker setup process. I actually have those same A90s toppers myself, and love them.

    I recommend running your receiver's speaker calibration system, and then play a movie clip with lots of overhead sound effects (like the opening few minutes of Bumblebee when Cybertron is under attack). If you find the Atmos channels aren't as loud as you like, manually raise their levels by one dB and replay the same scene. Repeat as needed until you get them dialed in — just be mindful of distortion.
  • Charlie White from Covington

    Posted on 6/9/2021

    I have a Nacamichi 7.1.4 system. What are the best setting for movies. For regular TV programs it seems stero sounds the best.

    Commenter image

    Kramer Crane from Crutchfield

    on 6/15/2021

    Hi Charlie, thanks for reaching out. I'm not familiar with your Nakamichi system, but trying cycling through the different modes and see if one stands out above the others. Dialogue performance is a key differentiator, so a scene with strong spoken word is worth a watch.
  • Carsten Haugaard from Aars

    Posted on 4/3/2021

    Just got a new LG OLED CX TV, it is stunning. However, there are only sound coming from the front speakers no matter what I do. The surround system is a Sony HT-IS100 and it may be the problem. Is it too old? 2008. Best regards Carsten

    Commenter image

    Kramer Crane from Crutchfield

    on 4/7/2021

    Hi Carsten, thanks for reaching out. I'm sorry to hear that you're having trouble with your gear. The best way to troubleshoot your system is to give our tech support folks a call — their toll-free number is on your invoice.
  • Thomas M Kolar from Castle Valley

    Posted on 3/14/2021

    I have a Yamaha RX-V485 receiver with a Klipsch 5.1 speaker layout. Some DVDs play sound only to the center when the receiver is set to Blu-Ray but play on the front and surround only when set to optical from the TV. ex) Flags of our Fathers" Blu-Ray Dolby Digital. Also, it only plays front and surround when using a cd player thru RCA connections. Am I doing something wrong? Tom

    Commenter image

    Kramer Crane from Crutchfield

    on 3/15/2021

    Hi Tom, thanks for reaching out. It's hard to say what's causing this; it could be a simple settings change, or there may be a malfunction somewhere in the system. In your shoes I would do a factory reset of the receiver and set things up fresh. Make sure each channel is connected securely, and rerun your speaker calibration software. I bet that takes care of the first issue.

    As for the music playback, there is a "5-channel stereo" mode that you can select to play tunes through all of your speakers at the same time.
  • steven matthews from louisville, kentucky

    Posted on 3/13/2021

    i have an onkyo TX-NR656 7.2 channel audio video receiver, i noticed that when i have my speakers configured in 5.1 i only see the dolby true hd displayed on the front panel, but when i set the speaker layout to 7.1 i see the dolby atmos logo displayed on the front panel, even though 5.1 speakers is connected not 7.1, and i be playing a dolby atmos encoded blu- ray disc, but when i play a DTS:X encoded blu- ray disc even in 5.1 or 3.1 the DTS:X logo shows regardless, why is that ? and i do select the right audio from the disc menu that i want to listen too, if i play a dolby atmos blu-ray disc through a 3.1 speaker layout, am i still getting dolby atmos even though the display say dolby true hd ?

    Commenter image

    Kramer Crane from Crutchfield

    on 3/15/2021

    Hi Steven, thanks for reaching out. Generally speaking, your receiver will try to give you the best processing available. Which audio format that is depends on the source you're watching (Blu-ray disc, Netflix streaming, etc.), how many speakers you have, and how they're connected.

    You should only see Atmos as a playback option if you have overhead effects speakers connected to your receiver (that'd be a 5.1.2-channel system, where the ".2" indicates the presence of overhead effects channels).
  • William Schenk from Bozeman

    Posted on 1/23/2021

    Does neural-x compress the audio in the process of upmixing a lossless format such as DTS-MA to play on 7.1 when the audio track is 5.1, or does it remain a lossless format?

    Commenter image

    Kramer Crane from Crutchfield

    on 1/26/2021

    Hi William, I'm not aware of any compression that takes place in that scenario.
  • Stephen bacon from Southampton

    Posted on 12/7/2020

    I'm running a Denon 3600 and power amp and 7.2.4 speaker layout. Are you saying I can't get Atmos but will get DTS X and Neutral X when I play a 4K disc?

    Commenter image

    Kramer Crane from Crutchfield

    on 12/7/2020

    Hi Stephen. If the 4K disc you're playing is encoded in Dolby Atmos, you should be able to select that as the audio format under the options menu of your Blu-ray player.
  • Max from Boca Raton

    Posted on 10/31/2020

    Jurassic Park was the first movie to be released in DTS in 1993. Your chart lists it as Dolby Digital.

  • Tahsin from Sydney

    Posted on 10/14/2020

    I have a decade old sony player with its 5.1 speakers. What happens when sound effect mode is set to DTS Neo6: Cinema and it receives 5.1 signal (not stereo) with hdmi/optical?

    Commenter image

    Kramer Crane from Crutchfield

    on 10/19/2020

    Hi Tahsin, thanks for your question. If you let me know which model receiver you have, I'm happy to see if I can get you a clear answer on how it would function in that scenario.
  • Nishant from Ghaziabad

    Posted on 10/3/2020

    If I have 2.1 sound bar with Dolby digital support then does it give Dolby effect properly from its 2 channels ? I face an issue that dialog volume is very low but background music is very loud in 2.1 soundboard.

    Commenter image

    Kramer Crane from Crutchfield

    on 10/6/2020

    Hi Nishant, I'm sorry to hear you're having difficulties. You may hear some benefits from the Dolby processing with a 2.1-channel sound bar, but dialogue can be a challenge, since spoken words are coming out of the same drivers that produce the soundtrack's musical score and sound effects. Normally, dialogue is best handled by a dedicated center channel (either in a 3- or 5-channel sound bar, or in a conventional 5.1-channel home theater system).