Keep in mind that we are starting out basic, and there are many variations on a theme. A surround sound system, simply put, should immerse you in the center of the sound field, while keeping a natural sound with voices in the correct location, usually tied to the video screen. A basic system consists of a source (satellite, dvd player, etc.), a processor/amplifier, and surround sound speakers. There are 3 basic forms of surround format. One of the oldest commercially successful systems is Dolby Pro Logic, which has now been upgraded to Dolby Pro Logic II and Pro logic IIx.There were previous formats that did not succeed commercially, such as the quadrophonic system.

    Dolby Pro Logic has one advantage over the other formats, and that is because it is mixed into a stereo source. What this means to you is that anything that has stereo outputs can provide a Dolby Pro Logic or Pro Logic II output, such as a standard cable box, cd player, vcr and the like. The other formats require a dedicated connection, such as a coaxial digital output or an optical digital output. These are often known by a couple of other names such as Toslink (fiber optic) or S/Pdif, and require the use of a very specific type of cable to pass the information. Digital optical, by the way, is not a wire but a plastic or glass fiber (fiber optic) that carries the signal. On high end equipment, due to signal transformation issues and something called jitter (signal timing issues) there are people that say the coaxial digital sounds better. On the other hand, the digital optical connection is not subject to electromagnetic (emf) signal interference problems like coaxial digital audio cables can be.

    The other 2 major formats are Dolby Digital and DTS. These, as mentioned above, require a wide bandwidth digital connection in order to function. These are both an improvement in sound quality over Dolby Pro Logic. A downside to the ProLogic (much improved in ProLogic II) is the handling of the rear channels. No rear channel separation information is encoded in the ProLogic signal, so the rear channel is essentially mono. ProLogic II uses a sophisticated algorithm to synthesize rear channel separation information, and it does a very good job, although the sound quality is still not as good as the digital formats can be especially in the area of dynamic range. The other downside to standard ProLogic is that the frequency information to the rear channels is restricted, which however does not hurt if your rear speakers are the miniature variety with restricted low bass response.

    Dolby Digital and DTS provide much improved dynamics and “punch” over Dolby Pro Logic in addition to much better rear channel separation and improved frequency response. These 2 formats can also provide a 6.1 and 7.1 channel signal. By the way, the .1 refers to the subwoofer, since it only reproduces the lower frequencies. As compared to the 5.1 format, 6.1 and 7.1 add additional rear speakers, and a rear center speaker. That's a lot of speakers!

    Dolby Digital and DTS are similar from a user's standpoint. Both provide excellent surround sound. DTS is said to provide a technically less compromised signal, and thus should provide better quality sound. I usually listen to music on DTS and watch movies in Dolby Digital, if I have a choice. Many DVD movies include both types of soundtracks. These may have to be selected in the setup menu of a particular dvd. Personally, I have not been able to determine a difference in the sound quality between these two formats provided that the dynamic range control in Dolby Digital is turned off. This useful feature enables you to decrease the dynamic range. Denon amps, for example, let you set the dynamic range control to high, medium, low or off. In a practical sense, what this does is lower the ratio between loud and low sounds, so that you don't have to turn the movie down for the explosions, then back up to hear the dialog. Many receivers now feature a 'night' mode which turns the dynamic range control to maximum. This feature is not available in DTS due to the format requirements.

Common Surround Formats:

Dolby Pro Logic IIx: Dolby Pro Logic IIx extends Dolby Pro Logic II to produce 6.1 or 7.1 output channels from stereo and 5.1 channel source material. It has a sophisticated sound steering algorithm that performs better and is more flexible than previous ( Pro Logic and Pro Logic II) versions. The original pro logic provided only a mono rear surround channel that was also bandwidth limited to 7 khz in the treble frequencies.

Dolby Surround: Dolby Surround is a 4 channel consumer version of Dolby Labs' multichannel film sound format. The 4 channels are encoded onto two audio tracks which can be carried on stereo program sources that can not carry digital formats such as videotapes and non-hd off air television brodcasts. These tracks can be decoded by Dolby Pro Logic systems to recreate the original (left, right, center, and mono rear) four channel surround effects.

Dolby Digital: This standard provides high quality digital sound. The source must be recorded in this format, and must be hooked to the surround receiver with a special digital cable, either fiber optic or coaxial for the format to be decoded. Dolby digital provides 5.1 surround sound consisting of a front left and right signal, center channel, left and right surround channels and a subwoofer output.

Dolby Digital EX: Dolby Digital EX improves the surround sound experience by adding additional rear speakers. It can be one or two speakers, set up as a rear center, or 2 rear speakers with a monophonic channel. Again, the medium must be recorded in this format for proper decoding.

Dolby Digital Plus:  Supports up to 7.1 channels with discrete outputs and data rates as high as 6 mbps. This results in even higher sound quality than regular Dolby Digital. This is the mandatory format for HD DVD. Dolby Digital Plus can support more than eight audio channels,but HD DVD and Blu-ray Disc standards currently limit their maximum number of audio channels to eight.

Dolby TrueHD: This is Dolby Labs next generation lossless format. Since the coding is lossless, it provides sound that is bit for bit identical with the studio master. It has an 18 mbps bit rate, up to 8 full range channels of 24 bit / 96 Khz audio, and is supported by the HDMI interface.

Dolby Digital Live: This is a format for PC or game console that converts any audio stream into a Dolby Digital bitstream for transport and playback through a home theater system.

DTS Digital Surround: DTS Digital Surround is a standard for providing 5.1 channels of discrete digital audio in consumer electronics products and software content. DTS digital surround is a lossless format, unlike standard Dolby Digital

DTS-ES: DTS-ES is a  digital audio format that delivers 6.1 channels of discrete audio in the consumer electronics market.  DTS-ES is also fully backwards-compatible with DTS decoders that are not Extended Surround equipped.

DTS Neo:6 DTS Neo:6 provides up to six channels of matrix decoding from stereo matrix material. This means that it works to provide 6 channels of output from sources that are not encoded in DTS, such as standard stereo television broadcasts.

DTS 96/24: DTS 96/24 offers an unprecedented level of audio quality for multi-channel sound on DVD-Video, and is fully backward-compatible with all DTS decoders. "96" refers to a 96kHz sampling rate (compared to typical 48kHz sampling rate.) "24" refers to 24-bit word length.

DTS Interactive: DTS Interactive delivers real time, discrete multi-channel interactive playback for PlayStation®2 games when connected to a DTS-equipped device such as an AV receiver.

DTS Virtual: DTS Virtual down-converts DTS 5.1- or 6.1-channel soundtracks to stereo while processing a realistic simulation of surround sound for two-channel equipment such as headphones.

Whew. Think they've got enough formats? and these are only the most common ones. 

Surround Sound Speaker Setup 

     We will assume you have a home theater or surround sound receiver. There are 3 main home theater speaker setups which you will see termed 5.1, 6.1, and 7.1 channel surround. You will also see mentioned the terms above including Dolby Pro Logic. Let's dispense with the latter first: if your reciever is only Pro Logic and not Pro Logic IIX (only older recievers at this point) you do not need to worry about 6.1 or 7.1 surround.  The two factors for consideration are: 1. how many channels does your system permit, and 2. Do you want to buy that many speakers? All the recievers that support more than 5.1 channels will also work fine with a 5.1 channel setup. Obviously, 7.1 will provide better surround sound than 5.1, but at the expense of  two extra speakers. If you have a limited budget you will have to decide whether to buy 5.1 higher quality speakers, or go for cheaper speakers to allow for 7.1 channels. By the way, the .1 channel is the home theater subwoofer. The subwoofer is, in my opinion, really needed for home theater. A system will work without it, but I don't recommend going without for home theater. The center channel is also very important for home theater, serving to anchor the sound to the video screen.

The diagrams above are the specifications for speaker placement according to Dolby Labs.  

Subwoofer Setup 

    Your subwoofer may have a switch for Dolby Digital / Pro Logic. If you have a Dolby Digital capable reciever set it to that even if you are using Pro Logic. The same goes if you have multiple inputs on your sub. If your input is labled LFE it is the equivalent of a Dolby Digital input. You want to use the input to the RCA style plug (or plugs) if you are using the subwoofer in a surround system. If you have speaker level binding post inputs, these are almost always for using the subwoofer in a non surround sound speaker setup. Preset the subwoofer level control to about halfway before running the white noise test tone to calibrate your receiver speaker levels. You absolutely must run the test and balance your speaker levels to have the surround system perform properly. Don't worry about the crossover frequency control on the sub for Dolby Digital or better systems. For Pro Logic set it to the point where bass in your main speakers drops off, which will require looking at the documentation for your speakers.

    If you are not using your sub in a surround system, you may, with advantage, use the speaker level inputs on the back of your sub. The advantage to this is if you have small speakers. The reciever left and right channels are connected directly to the subwoofer, and the left and right speakers connect to the speaker out connectors on the subwoofer. What this does is allow the sub to produce the low bass that the main speakers can not, which of course the other types of connections would do also. The advantage here is the fact that with the subwoofer connected this way, it filters the bass out of the signal, so your main speakers never try to produce the bass that they can't handle. This results in clearer, cleaner sound and more volume capability from your main speakers.  

    Back to speakers. The basic setup is 5.1, as mentioned above. The other formats are simply an expansion of the setup to provide two side/rear speakers, 2 rear speakers, and a rear center speaker. The center channel speaker has a very important job. It has to tie the dialog to the center of the video screen (when appropriate) and provide an even dispersion of sound to all listeners. This requires a special configuration to be most effective, so you will find dedicated center channel speakers. The left and right can be standard stereo speakers, preferably full range. In many cases full range speakers are not used for the rear channels, as they usually have less information channeled to them, and the low bass is often produced by the subwoofer instead. You may find dedicated rear channel speakers, and these are usually designed specifically to provide a diffuse sound field. These work better for movies, but in my opinion the diffuse sound field detracts from music listening. An exception are speakers like the Polk speakers that are switchable between dipole and bipole. This allows you to optimize them for both circumstances.

    My opinion is, start with what is ideal, then if you can't do that, do what is realistic. Ideally, all the speakers should be full range, and the same manufacturer and line so that they are all voiced the same. Probably the least important of these two is the full range aspect, provided you have a good subwoofer, as the receiver or processor can be set to allow the subwoofer to fill in missing bass. For this to work properly, however, it is best if the bass response of all speakers extends to at least 80 Hz. This allows for a more seamless integration with the subwoofer. Also, if you already have a couple of speakers you would like to use for the surrounds or the right and left front, go ahead. Everything will work fine with different speaker brands, just be aware that the surround effects will not be as realistic and enveloping as they would if all the speakers were voiced identically. This setup can be better for those who listen to music in stereo by allowing better quality speakers on the front left and right than could otherwise be afforded.

    Last but not least, a brief mention of setup. Once the system is physically set up, it will need to be set up and calibrated on your receiver/processor. This includes setting up the speaker sizes and distance from the listener. A good rule of thumb is that if a speakers bass response (-3 db point) extends below 80 Hz ( I personally would say at least down to 60 Hz) it is ok to set the speaker as large. Otherwise set to small. The speaker distance needs to be set, usually in feet. Once all the variables are set, the calibration needs to be done. This is done using a white or pink noise test built into the receiver/processor, and the goal is to make all the speakers sound the same volume from the listening position. A Radio shack sound level meter can help here. Some receivers autocalibrate, and come with a microphone to use for this purpose. It needs to be placed at the listening position, I would recommend at ear height. Well, that's enough for what is supposed to be a basic primer. It is all a little complicated for beginners, but once installed and set up should be fairly easy to use. Don't be afraid of your remote control or the instruction book! 

    We have an article with additional speaker setup tips, which includes the section on speaker setup above, but adds additional tips to ensure that you get the best possible sound out of your speakers without additional cost. Click here to read the speaker setup article.

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