A Comprehensive Guide to
Surround Sound and Audio Systems

Up to the mid-50's, home audio was still the single channel mono format. The first multi-channel audio appeared in the 60's with stereo sound, a two-channel sound format making use of left and right front speakers. Stereo remained extremely popular up to the early 90's.

Stereo sound represented considerable improvement over monaural audio, yet it still lacked the ability to envelope the audience during movie watching or music listening.

In other words, it still lacked that surround sound field so important to help the viewer get immersed into the movie action or experience the magic of a live concert in the home.

The first surround sound playback systems appeared in 1982 with the advent of Dolby Surround. Dolby Surround is a 4-channel matrix-encoded format that continued to build on the successful stereo format by encoding the sounds for two extra channels - the front center and the rear surround - over the two stereo left and right channels.

It is the addition of this single rear surround channel, played over two identical speakers placed on either side of the listener, which made it possible for this format to surround the audience with sound.

We start this guide to home theater surround sound by explaining the different sound formats. This will help you get a better understanding of what are the basic requirements on the amplifiers and speakers to deliver the desired surround sound experience.

We then proceed by discussing AV receivers and multi-channel audio amplifiers; topics discussed include what to look for before making a home theater receiver purchase, differences between 5.1 vs. 7.1 channel receivers, what makes a good amplifier, and the rather controversial subject of amplifier power.

One cannot discuss home there receivers and surround sound without looking at home theater speakers and the different requirements associated with the various channel speakers in a multi-channel audio setup, correct speaker placement, and an explanation of speaker specs.

We conclude this series of articles with a few inexpensive tips on how to enjoy better sound.

Multi-channel Surround Sound formats: Dolby, DTS, DVD-Audio, SACD

Multi-Channel Audio Formats:

Dolby Surround was to mark the first of a never ending list of home theater surround sound formats. In the process, the world of multi-channel surround got rather complicated - with many finding it difficult to grasp the different surround sound formats in use today.

Luckily, most DVDs come with multiple sound formats, often with Dolby Digital and DTS on a single disc to ensure playback compatibility; furthermore, some standards are backward compatible.

Most surround sound formats incorporate a minimum of six discrete rather than matrix channels - meaning each channel is unique and independent of the rest. The increase in the number of audio channels helps recreate a more realistic sound stage but this does not mean a 7.1 format is always your best option especially in the small room where it will be difficult to appreciate its benefit.

To help clear up the confusion on multi-channel audio formats, we prepared a series of articles that discuss the main characteristics of each of the different Dolby and DTS surround sound formats - including the latest high definition formats such as Dolby TrueHD and DTS-HD. In the process, we also discuss Dolby vs. DTS; is one really better than the others? Here is our opinion... 

We also discuss DVD-Audio and SACD - two popular multi-channel high-resolution audio formats designed for music listening.

And what about THX?

Not a standard by itself, THX Home Cinema aims at delivering cinema-quality picture and sound to the home.

Many do not have an understanding of the THX certification system and related technology, or what the different labels found on home theater THX certified gear mean. Yet to the 'everyday consumer', the THX label signifies that the highest standards have been used.

We are therefore presenting a short article that gives a brief overview of the THX certification program and related technology; in the process, we also see how THX relates to surround sound and home cinema.

Home Theater Receivers: Audio Power, Sound Quality and Speaker Loudness

Like home theater speakers, AV receivers and multi-channel power amplifiers are an integral part of a surround sound setup. The problem many face here is what exactly do they need to look for when making a home theater receiver purchase.

One important aspect we touch upon in our guide to home theater receivers is what really makes a good amplifier,  whether that comes in the form of an AV receiver or a power amplifier. As we explain in our article 'Understanding Amplifier Specs', factors like amplifier power rating, distortion levels, amplifier dynamic headroom, and signal-to-noise ratio impact a power amplifier's ability to deliver adequate audio power and sound quality. 

Equally important is determining the amplifier power required to match your expected level of loudness. Amplifier power is a much debated issue and a grossly misunderstood term. Many relate amplifier power directly with speaker loudness - which is not exactly the case. For more information on amplifier power, please refer to our article here.

One cannot discuss AV receivers and multi-channel surround sound amplifiers without raising up the issue of a correct multi-channel setup - in particular with respect to the delay settings in surround sound playback systems. Incorrectly set delays may break up the sound field. More information on delay settings is available in our article here.

Home Theater Speakers in Multi-Channel Audio

Surround Sound Speaker Systems Basics

Before delving into the topic of home theater speakers, we thought that it would be worth explaining a few basics about surround sound. Irrespective of the sound format in use, surround sound rely on the use of dedicated speakers that literally and physically surround the audience. The number of surround speakers depends on both the number of playback channels supported by the selected audio setup and the sound format in use.

This leads to an added complexity with surround sound; as further explained in our 'Surround Sound Basics' guide, the number of audio speakers in use does not necessarily match the number of audio signals supported by the surround format.

Home Theater Speaker Choice

But once you find the right set of good quality speakers for your liking, rest assured these will last for many years to come - much more than any other active system component in your home theater set-up.

You see, home speakers - like projection screens and home theater cables - form part of that category of technology that rarely gets outdated. If your speakers sound good within your room today, they will probably still sound good within the next 10 to 15 years. You will most probably be replacing your premium AV receiver within this time frame. Even more so, technology will make your latest HDTV outdated within a few years time. But this is not the case with good quality speakers.

So do not just buy the first set of home theater speakers you come across, or try to save on your home theater expense by opting for cheaper speakers. Our advice is to buy the best speakers you can afford. The extra effort invested in speaker selection will more than pay for itself through an enjoyable sound experience in the many years to come.

What to look for when choosing a set of home theater speakers?

We discuss the requirements associated with each of the different home theater speakers - front left and right speakers, center channel speakers, back and rear surround speakers - in our article 'Speakers for Multi-Channel Audio.' In the process, we also cover subwoofers and ceiling/in-wall speakers.

In the process, we explain the different speaker types that one may encounter in the home theater - from powered tower speakers and bookshelf speakers, to in-wall, ceiling speakers and dipole speakers. Shopping for audio speakers: There is more to a correct speaker choice in surround sound than just having an understanding of the different requirements associated with the different channels. In particular, speaker matching is critical for a unified and more realistic soundfield.

Polk Audio RC85i 2-Way In-Wall Speakers  (from amazon US)

Shopping for the best speakers is an art in itself; learning how to best shop for your home theater speakers as well as how to watch out for sales rep tricks when it comes to speaker listening tests during your speaker shopping process is essential for the best results.

We discuss the basics of how to shop around for the best speakers for a successful surround sound setup in our Home Theater Speakers Buying Tips.

Speaker Placement

Choosing the correct speakers in a surround sound setup is important but it is not enough; you need to watch out on your speaker placement. Correct speaker placement plays a crucial role in multi-channel audio.

Without the correct speaker placement, you will never achieve a convincing soundstage. As we further explain in our article Home Theater Speaker Placement, there are very specific speaker placement requirements associated with different multi-channel surround sound speaker setups to achieve a truly realistic listening experience. Not only, speaker placements vary also between music listening and movie watching. More information is available here.

Understanding Speaker Specifications

Our discussion on home theater speakers would not be completed without explaining the different speaker specifications one would come across when selecting and buying audio speakers for a home theater set-up. Why?

There is no better way to avoid costly mistakes than to research your speakers before you buy. But you cannot do this without having an understanding at least of the most common speaker specifications in use today.

For an explanation of the different speaker specifications, please refer to our article 'Understanding Speaker Specs.'

What about Single-Speaker Surround Sound Systems?

There are quite a number of single speaker surround systems such as the Polk Audio SurroundBar 50 surround system that can do a fairly accurate job in creating an immersive soundstage.

These single speaker surround sound solutions - also referred to as speaker bars or sound bars - are normally adequate for people with small rooms who do not want either to get surrounded with speakers, or want to avoid the clutter and installation hassle associated with multiple speaker systems.

While as further detailed in our wireless speakers guide,  wireless speaker solutions such as the Rocketfish reviewed on our site may help reduce the cable clutter, a single speaker surround is much simpler to set-up than a hybrid wireless speaker system.

Single speaker systems rely on virtual surround technologies - based on powerful digital signal processing techniques that can simulate the enveloping soundstage created by a 5.1-channel home theater surround sound loudspeaker system, over a two-speaker setup.

The Polk Soundbar 50 makes use of a Polk's proprietary SDA (Stereo Dimensional Array) technology in an attempt to simulate the effect of side and rear speakers. But there are others technologies as well, including the Dolby Virtual Speaker and SRS TruSurround. These technologies manipulate audio signals with sonic spatial cues by applying varying delays and phase-shifts between the different channels, based on extensive room-modeling technologies, to reproduce the sonic spectrum and dynamics of a properly placed 5.1 speaker system in a typical room environment.

But...

1] The expansive soundfield produced by single-speaker systems is limited to a rather restricted sweet spot.

2] Single speaker systems are best complemented by a compact powered subwoofer as their bass response is quite lacking.

3] While single speaker surround sound systems produce more than just an expansive soundfield, their performance comes nowhere close to that of a multi-channel surround sound speaker setup.

In other words, speaker bars provide the convenience of zero clutter at the expense of audio performance.

More information on virtual surround sound is available in our Virtual Surround Technology guide.

Tips for Better Home Theater Sound

We conclude this comprehensive series of home theater surround sound articles by presenting our easy-to-follow tips to a better home theater sound.

Whether you are in the process of purchasing a new set of speakers or wish to make the best out of your present audio set-up, knowing what to do and how to setup your sound system to get better sound is a basic step towards an enjoyable listening experience.

As we show you in our article, in most cases it just takes a few inexpensive modifications to an existing home theater sound system to achieve a dramatic improvement in the audio quality of your surround sound.