Surround Sound System

 Surround Sound Formats

The principal format for digital discrete surround is the “5.1 channel” system. The 5.1 name stands for five channels (see figure 1 below) (in front: left, right and centre, and behind: left surround and right surround)of full bandwidth audio (20 Hz to 20 kHz) plus a sixth channel which will, at times, contain additional bass information to maximize the impact of scenes such as explosions, etc.  this channel has only a narrow frequency response (3 Hz  to 120 Hz), thus it is sometimes referred to as the “.1” channel. When added together, the system is sometimes referred to as having “5.1” channels.

DTS

DTS was introduced to the public in 1993 with the release of Jurassic Park. Presently, over 5000 theatres worldwide are equipped with DTS playback equipment and over 100 movies to date have been DTS encoded. The DTs format for movie theatres, also known as DTS-6, and the format proposed for home entertainment, are quite different. We will discuss the former first.

Introduction

We are now entering the Third Age of reproduced sound. The monophonic era was the First Age, which lasted from the Edison’s invention of the phonograph in 1877 until the 1950s. during those times, the goal was simply to reproduce the timbre of the original sound. No attempts were made to reproduce directional properties or spatial realism. The stereo era was the Second Age. It was based on the inventions from the 1930s, reached the public in the mid-‘50s, and has provided great listening pleasure for four decades. Stereo improved the reproduction of timbre and added two dimensions of space: the left – right spread of performers across a stage and a set of acoustic cues that allow listeners to perceive a front-to-back dimension.

7 – Channel Surround Circuit

It creates a 5-channel real surround with the other two channels being totally virtual. This becomes possible by adopting a radically different approach – the output from the amplifier is split into lows and highs of frequencies and fed into separate speakers. The lows are fed to rear speakers and the highs to the front ones. One distinct feature is that the direction of speakers is directly opposite to that in the Dolby Surround System.

SDDS

Sony Dynamic Digital Sound is the newest of the three formats to hit the market. The system was released in early 1994, and kits were made available to dubbing studios and film printers to adapt industry standard film printing equipment so as to provide an easy ability to record and print SDDS films.

THX IN 5.1

The THX Sound System was developed in 1982 durint the production of Return of the Jedi. The system was developed by Lucas film’s corporate technical director Tomlinson Holman; thus the new sound system was referred to as the Tomlinson Holman eXperiment. THX is a sound system designed specifically to reproduce film sound exactly as it was recorded by the film maker. THX systems are more 5.1 ready than most other systems. Home THX have always employed separate amplifier channels for two surrounds, because THX controllers apply “decorrelation” to cover Pro Logic’s mono surround signal into two spacious “steriozed” surrounds. So with a THX system, it is already using the stereo amplification that DSD or DTS required for surround channels.

Conclusion

With the amount of technological advances that are occurring in the field of surround sound, it will be no surprise, if the stereos we know become obsolete soon. The new proposed DVD has already chosen DSD as preferred format for audio.