System Building

Building A New System

This page is a guide to building a new home cinema based around a dedicated surround sound amplifier. All the different system components are explained, including surround sound amplifiers, video sources and speakers, plus an explaination of how it all fits together.



Looking around the other areas in this site you will find information about all the equipment and formats that are used in a home cinema system. This area shows you how each of the components work together. Please refer to the other areas for exact details about the different types of components and which apply to the system that you will be building.

The other System Building page on this site deals with home cinema systems that are added to a hi-fi setup in order to maximise and maintain the sound quality of stereo sources such as CD and Minidisc. This page looks at building a home cinema system from scratch, with no existing components, and no desire to add or maintain a stereo hi-fi.

In simple terms, a dedicated home cinema consists of a video source, a multi-channel amplifier, a selection of speakers and a television. The differences between a dedicated system and one that has been added to a hi-fi are subtle but inportant. Firstly, and I would say most important, is the resulting sound quality. A home cinema amplifier has all the amplification and decoding circiuts in the same unit, which are built to work well with each other when presenting surround sound. Add to this the numerous special digital sound processing (DPS) circuits that are common to all A/V amps, and you have a single box that offers great performance, at a cost usually less that separate boxes containing the individual components. Secondly, setting up the different speakers is made easier because there is only one amplifier, rather than separate amplifier and processor channels as found in add-on hi-fi systems. Finally, a dedicated system is intended for cinema sound, and only cinema sound. Hi-fi playback quality is generally lacking when compared to a similar hi-fi, mainly due the fact that the circuits within an A/V amp are designed exclusivley for multi-channel surround rather than delicate, top quality stereo. The extra amplification and DPS circuits usually have an impact on stereo playback.


This is a diagram of how the most common Home Cinema systems are linked together:


Basic System Diagram



You can see that the above system is based around a video source component. This could be anything that provides audio and video signals, such as a video recorder, DVD player or satellite receiver. It connects to the television only to display the picture, while the separate home cinema amplifier handles the sound processing and drives the separate speakers.

The video source should be the strongest part of the system, as a top-of-the-range amplifier or television will not compensate for a poor source signal.



The source component needs to be connected to a television using the best quality connection you can get, with most being connected using SCART cable, although higher quality connections can be made such as composite video or the excellent S-Video connection. The picture is displayed on the television with the TV's volume turned right down when watching a movie with surround ound. The amplifier handles all the sound.



The audio information from the source component is sent to an external Home Cinema (A/V) amplifier and is the key to a good home cinema system. The main reason for building a Home Cinema system is to enhance your viewing experience, and the most important and fundamental way to achieve this is to use separate sound amplification and speakers rather than the speakers in the television.

A dedicated A/V amplifier has a number of features not found in a standard stereo hi-fi amplifier. First, it will have extra amplification for the additional rear and centre speakers needed for home cinema, plus it may have an output for the inclusion of a separate sub-woofer that provides deep, wall-shaking bass sounds.

It will also contain some form of surround sound decoder. All A/V amplifiers have a Dolby Pro-Logic decoder as a minimum, while many units will also contain decoders for digital surround such as Dolby Digital and DTS. Digital Surround is explained in much more detail in the Sound Formats area. Finally, a minimum of five speakers and possibly a sub-woofer need to be connected to the A/V amplifier in order to hear surround sound. Normal stereo soundtracks from CD or other source components will be heard in stereo through the front left and right speakers only, unless you want to add one of the available Sound Processing (DSP) modes such as Hall, Arena, etc.



The basic layout of any Home Cinema system is illustrated in the diagram below.

Notice where the speakers and television are placed in relation to the listening position - all systems should be set up in a similar way for the best results. For clarity, the other hardware, such as sources, amplifiers, etc., have been left out. Those components can be placed in any location around the room, wherever it suits you best.


3D Room Diagram


You should think about a few things before deciding which particular products you will need for your system. Try and ensure that all the speakers are from the same manufacturer and that they are all rated at a similar power level and performance. This is particularly important for the front three speakers where the soundstage can be broken by an unsuitable centre unit.

The rear surround speakers will be affected by the type of surround sound decoding found in your system, or the type you plan to add later. For a Dolby Pro-Logic system, the audio signal to the rears has a lower power than the front speakers, and has a limited bandwidth. As a result, you can use rear speakers that are smaller and have a lower power rating because they are not likely to be driven very hard. In a digital surround sound system, such as Dolby Digital, the rear speakers are fed a signal that can be as powerful and loud as the front speakers. In these systems, the rears should be the same as the front units, or at least closely matched.

You should consider the type of surround sound you want now and what you may want in the future. Amplifiers with digital decoders built-in are a good option to start with, but in the future, if different types of decoders need to be added, the amplifier will need what is known as a "six channel input", regardless of whether the amp already has a digital surround decoder or not. This input allows the addition of a separate digital decoder at a later date (or even a separate DVD-Audio player), and these days most home cinema amplifiers and receivers have them. An A/V amplifier will also have lots of inputs for other video and audio sources, so more components (CD player, Minidisc, DVD player, etc.) can be added as needed.

A/V amplifiers and receivers will all have Dolby Pro-Logic decoding. If no digital decoders are included, make sure it has a six-channel input to add Dolby Digital, DTS or DVD-Audio at a later date, if these things are important to you. The better option is to get an amp or receiver with Dolby Digital decoding built-in; the cost of the Dolby Digital decoding will be less than adding a separate decoder in the future. The very best option is to get a model that has both Dolby Digital and DTS decoders included. These are widely available and the extra cost of the DTS technology is very small compared to adding a DTS decoder later. All these models will feature Dolby Pro-Logic as standard. Considering that the digital surround sound arena is dominated by Dolby Digital 5.1, with DTS sound becoming more and more widely available, it's a safe bet that an amp with all of the above formats will not become redundant in the lifetime of the machine. No other sound formats are planned (as far as we know!) and with DVD-Video supporting Dolby Digital, this format should be the one to choose over any other. As stated above, a six-channel input on the back of any home cinema amplifier or receiver is recommended just to be sure.



Speaker placement is very important. The front left and right speakers should be placed at either side of the television, spaced apart about the same distance as the distance between your listening position and the speakers themselves. The centre speaker should be placed above or below the television, with the front face of the speaker on the same line as the two main front units, or slightly further away. Placing the front speaker closer to the listening position will spoil front effects for people seated off-centre at the edges of the room.

The two rear speakers should be placed ideally at the sides of the listening position, about 60cm to 100cm above head height, and pointed at each other. If this is not possible, rear speakers can be placed on the wall behind the listening position in the corners of the room, either facing across the rear wall at each other, or actually facing the wall if the speakers are close to your listening position. This last option prevents the rear speakers from sounding dominant and masking the sound from the front three speakers.

A sub-woofer can be added to most systems to carry low bass frequencies. Bass is non-directional and therefore the sub can be placed anywhere in the room - behind the sofa, in the corner, or even used as a coffee table. Move the sub-woofer around to find the position that sounds best in your room, everybody is different.