top of page

Surround Sound Formats Explained

When you’re looking to buy a surround sound system, you might be overwhelmed by the number of options and terms. Should you get a 5.1, 6.1, or 7.1 surround sound system? What is Dolby Digital? And what is Dolby Atmos? All those surround sound formats on your receiver can be confusing.

We love making technology easy to understand! We’ve put together this guide to help you understand how surround sound works and go over all the popular surround sound format options. We know this can be confusing, so we’re going over each format to help you understand.

What is surround sound and how does it work?

Surround sound is an audio technology that immerses you in sound. If you have ever been to a movie theater, you’re familiar with this experience. A home theater system is another great way to experience surround sound. This technology has been around for decades, but today’s surround sound systems offer an incredibly realistic listening experience.

Surround sound is achieved by strategically placing speakers around the listener. In a home theater, this means that speakers are placed in locations around the room so that you hear sound from all angles. The typical arrangement consists of a center speaker in the middle of the room, two speakers on the right and left, and two speakers behind or to the sides of the main listening area. The exact placement of the speakers may be different depending on the size and shape of your room.

Sounds pretty simple, right? While a surround sound system is basically a set of speakers placed around a listener, there’s a little more to it than this. So, how does a surround sound system work?

You’re probably familiar with stereo sound. With a stereo system, there are two different audio channels — a right and a left. Each channel is sent from the receiver to the corresponding right or left speaker. A surround sound system is a multi-channel system, meaning the receiver sends multiple audio signals (or channels) to different speakers around the room.

Types of surround sound systems

Although there are various ways of setting up a surround sound system, there are three main configurations – a 5.1, 6.1, and 7.1 channel system. This sounds complicated but it’s not. These numbers represent the number of channels in the audio system. The first number refers to the number of primary channels, and the number after the dot refers to the number of subwoofers in the system.

A 5.1 speaker system is usually set up with 3 speakers in front of the listening area, 2 speakers in the back, and a subwoofer in the back. The 6.1 system is set up the same way, except it has an extra speaker in the back. And the 7.1 system has 3 speakers up front, 1 on each side, and 2 in the rear.

Surround Sound Formats

Now that you understand the basics of how a surround sound system works, you should be able to understand the surround sound formats a little better. Sound is stored in an encoded form. A receiver takes this encoded sound and transmits it to all of the speakers. This encoded sound is what tells each speaker what sound to play. This is why you might hear a unique sound from each speaker, or one speaker might play a louder sound than the others.

There are a number of formats used to encode sound. A receiver decodes the stored sound information and sends the sounds to the appropriate speakers. However, some receivers are compatible with different surround sound formats.

It’s important to know what surround sound formats your receiver supports. Although many formats exist, some are universally supported while others are optional, and may not be compatible with every receiver or Blu-ray player.

The most common surround sound formats include:


LPCM (or PCM) is an audio format that stores audio signals in an uncompressed form. The major advantage of LPCM is that uncompressed audio means there is no loss in sound quality. This is the standard format for all CDs and DVDs. This format is supported by all receivers and Blu-ray players.

Dolby Digital

Dolby Digital is an audio encoding technique that compresses the audio channels so that they take up less space. Dolby Digital can be found on many Blu-ray discs and can support up to 6 channels, 5 for the primary speakers and one for the subwoofer. It’s often referred to as Dolby Digital 5.1, but the name Dolby Digital refers to the encoding technique, not the number of channels it supports.

Dolby Digital Plus

Dolby Digital Plus is an upgraded version of Dolby Digital. It uses a more efficient encoding technique and supports up to eight channels. It’s used on many Blu-ray discs and is compatible with HDMI.

Dolby Digital Ex

Dolby Digital EX uses the same encoding method as Dolby Digital, but it adds a third rear channel for greater clarity and detail.

Dolby True HD

Dolby True HD is a surround sound format that uses lossless compression. That means that it compresses the data, without reducing the audio quality. It supports up to 8 audio channels and is used mainly with Blu-ray discs.

Dolby Atmos

Dolby Atmos is a new way of delivering audio. With Dolby Atmos, surround sound is delivered from all directions. Instead of just having extra speakers in the front and back, Dolby Atmos provides up to 64 channels of surround sound that not only go to the front, back, and sides of your room, but also to the ceiling! But, this technology also delivers sound in a different way than Dolby Digital.

Dolby Atmos is a new technology that can create a "sound bubble" around the user. It's beyond the typical 5.1 or 7.1 systems that just send audio to each speaker in a set configuration. The technology can create over a hundred sound objects, which allows the sound designer to place each sound and voice to exact points within the sound field rather than simply assign them to specific channels. For example, you can actually hear rain falling from above your head or a train moving from left to right with this surround sound format.

To experience the completely immersive experience of Dolby Atmos, you will need more than the typical 5.1 or 7.1 speaker configuration. In-ceiling speakers allow for the best experience, or you can add height channel speakers to your setup.


DTS stands for Digital Theater Systems. It’s a sound encoding format that many believe offers better audio quality than its competitor, Dolby Labs. DTS uses less compression in the encoding process than its competitor. As a result, when decoded, DTS provides a better listening experience, according to some listeners. Similar to Dolby Digital, it supports 6 channels but its encoding process is different. DTS is used in theaters and is mandatory in HD DVD and Blu-Ray discs.


DTS:X is DTS’s alternative to Dolby Atmos. This surround sound format creates a realistic 3-D sound experience and reproduces sound with object-based audio. Object-based audio is a way to encode and transmit sound digitally. It involves mapping unique sound elements to positions in a virtual soundscape. Each position is based on the distance between the listener and the sound object.

DTS:X and Dolby Atmos are both incredibly popular because of the way they recreate sound, which is better will depend on who you ask. Dolby Atmos is more complicated to set up, so if you're not a tech-savvy audiophile, DTS:X will be easier to integrate into your home theater. You can use any standard speaker configuration with DTS:X, such as 5.1 or 7.1. Dolby Atmos, on the hand, requires additional speakers or ceiling speakers to produce the same effect.


Many people mistakenly believe THX is a surround sound format. THX is not a surround sound format like Dolby Digital or DTS. It’s a certification that defines the highest standards for home theater equipment. This certification assures that products deliver accurate, cinema-like experiences at home.

THX is a certification that was developed by Tomlinson Holman. He worked on the Return of the Jedi soundtrack with Lucasfilm Ltd. They wanted to make sure the soundtrack was accurately reproduced in home theaters. Many gamers look for the THX logo on their devices or use the THX Spatial Audio App to ensure they are getting the best experience when they are playing their favorite games.

Let SmartVolt take the confusion out of surround sound

These are the most common surround sound formats. There are many others, but these are the ones you are likely to find available in most home theater systems. Setting up a home theater system can be a confusing and overwhelming endeavor if you’re not a professional.

SmartVolt has been designing home theater systems for decades. Let us design one for you. Contact us at 505-903-6911 for more information. We can design a system that is perfect for your needs and budget.


bottom of page