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What Does Each Speaker Do in a Surround Sound System?

A home theater surround sound system is comprised of several speakers - but they are not there just to give you more things to dust!

Before getting into the details of choosing your speaker system and setting it up, it can be useful to start at the beginning and look at the basics.

If you understand the role of each speaker in your system, then it will make it easier to install them to get the best sound possible in your room.

So, what does each speaker do exactly?

The Speakers in a 5.1 Surround Sound System

The most common speaker system for a home theater setup is a 5.1 system. We have six different speakers in a 5.1 surround sound system, and they all do different things. 

5.1 Speaker Configuration in a Surround Sound System 5.1 Speaker Configuration in a Surround Sound System

All the speakers need to be positioned fairly accurately, except for the subwoofer where the location is less important.

What Is a Center Channel Speaker?

The center speaker is very important as it reproduces most of the dialogue in a movie.

Some may argue it the most important speaker for movies and general TV viewing.

It is often a different shape and design to the other speakers as it has this specific purpose - and it is one of the most critical speakers in the whole system.

If you can't hear the words very well, then you're not going to enjoy watching movies very much, are you?

The whole unit is often wider than the other speakers in the system, to broaden the soundstage when people are talking on screen. Also, a flatter/wider design can make it easier to discretely position the speaker above or below the TV screen.

Polk Audio Signature S35 American HiFi Home Theater Center SpeakerPolk Audio Signature S35 American Hi-Fi Home Theater Center Speaker

You can see the common shape from the popular Polk Audio Signature S35 American HiFi home theater center speaker, pictured above. The wide and slim design make it perfect for placing under your TV screen.

A center speaker may have multiple woofers and tweeters to spread the sound field. A standard speaker will usually have the tweeter set above the woofer. In a center speaker, the tweeter is usually inline in a horizontal position.

You could use a standard speaker as your center speaker but this might be more difficult to position around your TV. And, you wouldn't have the extra design features available on a dedicated center speaker.

While it is mainly used for dialogue, in a 5.1 mix it will also be required to reproduce music or sound effects. So, it will ideally have a wide frequency response like the front left and right speakers.

Can you run a surround sound setup without a center speaker? Yes, you can. You can have any speaker layout you like. In this case, you just need to disable the center speaker in your AV receiver’s setup menu. The soundtrack will then be downmixed to 4.1.

It won’t sound exactly as intended, as it was originally mixed for 5.1 channels. However, some people prefer the sound without a center speaker. FYI, I‘m not one of them!

What Do the Front Left and Right Speakers Do?

The front left and right speakers reproduce most of the music and sound effects in a soundtrack. But will also be used for dialogue when the voices move to the left or right of the screen.

These speakers are crucial and need to reproduce a wide range of frequencies. From the low bass in music and effects to high tones in instruments like bells and cymbals. The really low bass will be handled by your subwoofer. More on that later.

Because the front speakers are required to reproduce the most important music and sound effects, ideally they should be of high quality. Having said that, you might consider how you will be using your system.

If you are mainly watching movies and TV on your system, you may get away with spending less money on your front left and right speakers.

However, if you will also be listening to music on the same system, then it is these speakers that will be used for the stereo playback of music. So, it will be more important to get good quality speakers.

The bottom line is you should try not to skimp on the front three speakers. They really lay the foundation of your movie sound.

Ideally, the sound of the front left, right and center speaker should blend nicely. They work together to give the important front soundstage in a movie. Many people will buy a center speaker that is from the same brand, or range, as their front left and rights. This ensures that they will sound good together. However, you don’t have to.

Polk Audio Signature S15 American HiFi Home Theater Compact Bookshelf SpeakerPolk Audio Signature S15 American Hi-Fi Home Theater Compact Bookshelf Speaker

An example of speakers in the same range, is the Polk Audio Signature S15 American HiFi home theater compact bookshelf speakers, pictured above. You can see they have the same styling as the center speaker pictured in the last section. You can also be sure that they will work well together, as they will be built with similar technology.

If you do have speakers that are a different brand, you can use equalization on the AV receiver to try and balance the sound.

There are a few different types of speaker that you can use for the front left and right. Floor standing, bookshelf or satellite - it doesn't really matter that much. It’s down to your preference. But, they need to work well with the center speaker.

The type of speakers you buy will usually come down to:

  • the size and shape of your room
  • your budget
  • the type of audio you will be playing through them - movies or music

What Do the Surround Speakers Do?

The surround left and right speakers mainly reproduce the surround music and effects. They need to reproduce a similar range of frequencies to the front left and right speakers. But, are less critical than the front speakers as they are used less.

Therefore, whilst they will ideally be of a similar quality to the front speakers, it is more common to save some money on the surround speakers. You will not lose so much in overall quality. But, if you can, keeping the same high-quality speakers in the whole system is the best way to go.

In 7.1 surround sound systems, there are two more speakers at the rear for an even greater sense of space. These extra 7.1 speakers fall into the same category as the surround left and rights. Like the surrounds, they will ideally be the same quality as the front speakers. But, you can get away with less here and may not notice too much.

SVS Prime Satellite SpeakersSVS Prime Satellite Speakers

The surround speakers are more likely to be smaller satellite, bookshelf or in-wall speakers. The SVS Prime satellite speakers, pictured above, are a good example of high-quality satellite speakers that are ideal for use in a home theater sound system.

If you have space (and the money), there's no reason why you can't have floorstanding speakers as surrounds. However, it may be more difficult to keep them from overpowering the sound from the front – and to get them in the ideal position. In a surround sound mix, the rear channels usually don't have much low-end audio. It is routed to the subwoofer. Therefore, using full-range floorstanding speakers for your surrounds might be considered a waste of their potential. They will sound great for 5.1 music though!

The Different Types of Surround Sound Speakers

Surround speakers are often direct-radiating or monopole speakers. This sounds more complicated than it is. These are the ‘normal’ type of speakers you are used to, which fire the sound forward from the speaker. Like the ones pictured above. This is also the type of speaker usually used at the front.

However, there are two special types which are commonly used as surround speakers. They are called bipole and dipole speakers.

What Are Bipole Surround Speakers?

Bipole speakers are bi-directional. That is, they have two speakers that fire sound in opposite directions at the same time. They are positioned so that the sound is pushed around the seating area, but not directly at the people listening.

Bipole speakers are ideal as surround speakers in a 5.1/7.1 system as they spread the audio better than normal direct-firing speakers. They create a less directional sound. The sound from these speakers is also in-phase. I’m not going to bore you with the details, but it is an important difference when compared to dipole speakers.

What Are Dipole Surround Speakers?

Like bipole speakers, dipole speakers also have a pair of speaker drivers in the same cabinet. But, there is one major difference. The sound in dipole speakers is out of phase i.e. when one side is pushing the other side is pulling. This creates a very diffuse sound that is difficult to pinpoint.

It is important to install this type of speaker in the correct position to get the right effect. Bipole speakers are more flexible when it comes to positioning.

This video gives a nice summary of the different types of surround speakers:

What Does the Subwoofer Do?

The subwoofer is completely different to the other speakers. The subwoofer is there for one reason alone - to reproduce the low bass end.

A subwoofer can make an amazing difference to the perceived quality of your sound system. Many people don't often have the equipment available to them to play such low frequencies.

When you have a good bass system in your room, you may be surprised as to how this improves the listening experience. It can really help to fill out and support the sound from the other speakers. And, you don’t need to have it so loud that it shakes the room. Having it balanced so it just reinforces the bottom end is usually the best way to go.

Of course, you can turn it up really loud if you like!

Subwoofers are usually housed in a large, heavy box. Some look rather cool... some don't! The unit itself must be pretty big, as this is the only way to build a speaker to reproduce low bass frequencies. The physical size is required to get that deep bass in your room.

Having said that, you can get many different sizes to fit into your space. The cone in a subwoofer can range from around 6” up to around 15”. The larger the cone, the better it can reproduce very low frequencies.

Klipsch R-115SW Powered Subwoofer with WA-2 Wireless Subwoofer KitKlipsch R-115SW Powered Subwoofer with WA-2 Wireless Subwoofer Kit

Subwoofers designed for home theater are generally powered. By this I mean they have their own internal amplification. Therefore, your AV receiver doesn't actually provide the power to the sub. A powered subwoofer needs to be connected to the mains, and then it will usually get the signal via an LFE connection from the AV receiver.

These days, more subwoofers come with wireless connections. The Klipsch R-115SW powered subwoofer, pictured above, comes with a wireless subwoofer kit. You can still use a cable if you wish, but with the wireless kit you are free to place the sub anywhere in the room.

Conclusion

Although it might not seem important, it is easy to see why it is useful to know what each speaker is doing in our system.

Our surround sound speaker systems do insist on having all those pesky speakers cluttering up our room. Once we know why we can make a better judgment about which type of speaker we want. Or, what system would be better suited for our home.

You are now in a better position to judge if satellite, floor standing or bookshelf speakers will be right for your room. Or maybe bipoles and dipoles. If you're still unsure, you might want to check out my guide to the best home theater speakers for surround sound in 2017.

Also, when it comes to getting all the speakers in the right position, you will understand a little more about what is required. This is because you understand the job of each speaker in the room.


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