Surround Sound has its beginnings in the movies. Surround Sound was an essential way of drawing audiences into the world of cinema. In addition to the screen images, the dialog, the feeling of ‘being there” through sound effects, and the music that embraces audiences have been combined to create a thoroughly enjoyable cinematic experience.
Dolby Laboratories has contributed significantly to movie sound development. Its first major development was Dolby Stereo, followed in 1982 by Dolby Surround for the consumer market. Improvements in this technology led to the development of Dolby SR (Spectra Recording), which was introduced for consumers in the form of Dolby Surround Pro Logic in 1987.

The primary difference between the consumer formats of Dolby Surround and of Dolby Surround Pro Logic is that Dolby Surround uses three channels (Left, Right and Surround), while Pro Logic uses four channels (Left, Right, Surround and Centre). With the addition of the Centre channel, the distribution of sound elements becomes clearer In addition, by installing the adaptive matrix circuit into the playback side, Pro Logic emphasises the sound directions.

Dolby Pro Logic is a totally analogue format, the advantages are a Pro Logic amp can take the stereo sound from any stereo input and decode the pro logic encoding in the stereo sound track. Pro Logic has since been superseded by Dolby Digital, a superior sound format that is mainly found on DVDs, fortunately nearly all Dolby Digital amps are backward compatible with Pro Logic and therefore your VCR and TVs sound output.

Apart from the superior sound quality you will find on Dolby Digital the main difference you will notice is the need to connect a digital cable from you DVD player to your Dolby Digital amp. Pro Logic didn’t need this extra cable as being an analogue format the surround audio was matrixed on top of the standard left and right audio channels.