If you have ever been shopping for a cool home speaker system, you may have encountered certain audio brands like “Dolby” and “DTS.” In fact, most speaker products boast tech specs like “Dolby Atmos.” These brand names refer to different audio tech formats that create the surround sound experience in your home. You may have also encountered a string of decimal numbers following audio tech brand names, like Dolby 5.1. What do those numbers mean? What are the differences between these audio formats? If you are confused about these crucial features of surround sound speakers, as most regular consumers are, read ahead for explanations of most common modern surround sound formats.
Dolby Digital 5.1
Dolby Digital was created way back in the early eighties, when laser discs were a thing. Most people reading this article may not have even been alive back then. The point is, when laser discs came out and people started watching movies at home, Dolby created its Dolby Digital audio format. While there was a surround sound format called Pro Logic that came before, it was really Dolby Digital that made surround sound truly popular.
Before this digital format came around, most people used stereo speakers. Both stereo and surround sound formats are channel based, which means more than one speaker delivers audio. However, stereo traditionally uses two speakers—center and left or center and right—to create a field of sound right in front of you. It’s like listening to a live music performance from the middle of the front row. Stereo sound is the most used audio format in the music industry. Movies, on the other hand, create these sound fields not just in front of you, but from behind, sides and even above. You know, surround sound.
Surround sound became a thing with Dolby Digital 5.1. The numbers in this format refer to the speakers and the sub, meaning that this format supports 5 speakers and 1 subwoofer. The subwoofer delivers low-frequency audio effects that can really bring movie sound effects, like explosions, to life. To this day, Dolby Digital 5.1 is the default surround sound system for home theater audio systems, which now even includes Blu-ray discs.
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When Dolby Digital became popular, a rival soon came along—the Digital Theater Systems (DTS) brand. DTS became quite popular after this format was used for sound effects in the first Jurassic Park movie. While the movie was a hit, the audio format became a mainstay on newly released DVDs and LDs. Compared to the original Dolby Digital format, DTS delivers more information thanks to a higher bit rate. It’s like those “kbps” differences in MP3 files. While there is a quality difference between Dolby Digital 5.1 and DTS, it’s not something most people can actually notice.
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Dolby 6.1 and 7.1
Dolby eventually upgraded 5.1 surround sound with additional speakers. These days you are more likely to encounter 7.1 than 6.1 speakers.
With Dolby Digital 6.1, the brand introduced a sixth speaker that could be placed in the back or the center of a room. If you think that makes surround sound less “surround,” most people at the time thought so too. The advantage of this sixth speaker is that it can create the audio experience of something approaching from behind you or receding from you. It’s a pretty cool effect to have when you watch horror movies. DTS also offers a 6.1 format that essentially works the same way.
Dolby Digital 7.1 format was created for Blu Ray and HD DVD video formats. This version essentially extends the number of speakers in the back from one to two. And these two speakers work in stereo, made possible by the higher data storage capabilities of Blu Ray discs. The 7.1 format can basically carry a lot more audio information. Dolby released 7.1 in two versions, the regular 7.1 and Dolby TrueHD. In regular 7.1, audio data is compressed while TrueHD does not compress anything and sounds slightly closer to movie theater audio. DTS, also, offers similar 7.1 formats.
Atmos is the latest audio format from Dolby and it’s usually marketed with 4k video gadgets. Dolby Atmos speaker setup is 7.2.4. So it supports 7 speakers, 2 subwoofers and 4 ceiling speakers (in ceiling or upward firing) for a total of 11 speakers. Atmos can process audio coming from 128 different objects in a single movie scene. In actual movie theaters, Atmos can support up to 64 speakers. This changes the theater experience fundamentally. In the past, only half the speakers would create a single sound at once. With Atmos, distinct object sounds each come from different locations.
Atmos is available for home entertainment systems, especially in HD. If you want more directional sound to create an immersive theater experience, Atmos is highly recommended.
DTS:X debuted in 2015 and is the direct rival to Atmos. The main difference between the two is that DTS can process audio info from an unlimited number of objects in a scene, while Atmos limits the number to 128. At home, DTS:X can support up to 32 speakers. If you have a new A/V receiver, you can do a firmware update for DTS:X. However, it should be noted that Dolby Atmos is more popular with movie studios and DTS:X, so there aren’t that many feature films with audio mixings that support this format.
Which Should You Choose?
It really remains up to you. Choosing between the Dolby and DTS is down to preferences. However, Dolby is the more popular format among most movie studios. So most of your favorite movies probably have audio mixed with Dolby formats in mind.
Technically speaking, a Dolby 5.1 system is adequate for watching and enjoying surround sound for nearly any movie. If you can add more speakers, you can upgrade to 6.1 or 7.1. You can buy Dolby Atmos or DTS:X supported speakers to future-proof your home entertainment setup.
What you should not choose surround sound for is listening to music. If you are a music lover who mostly uses home speakers to listen to song tracks, then you need a stereo hi-fi system. Music tracks are still produced in stereo, so a surround sound speaker system would be rather useless or inconvenient for listening to music tracks.