Surround Sound Home Theatre Receivers
Pro Logic, Dolby Digital, DTS, THX and DSP - What do all these names and formats mean?
Surround sound didn't happen overnight. It grew out of stereo and evolved into today's state-of-the-art discrete digital multi-channel formats. There are multiple different surround sound formats, and at Visions Electronics we have a great selection of surround sound receivers from brands such as Yamaha, Onkyo, Pioneer and Harman/Kardon. Your surround receiver will be the key building block of your surround sound system, and before building your dream home theatre setup, it helps to know the differences between all the formats, and understand what all the jargon means.
Dolby Pro-Logic
To accommodate surround information into movies, Dolby Laboratories developed the Dolby Pro Logic surround system which is found on nearly all movies made in the past twenty-five years. While there have been improvements to the Pro Logic format since with Dolby Pro Logic II, Pro Logic IIx and Pro Logic IIz, it was the first incarnation of surround sound which was suitable for videotape. Today however, if you'd like to hear your DVD and Blu-Ray movies at their very best, you'll also want the latest digital surround sound capabilities that are described in the next sections.
Dolby Digital
The most popular of the digital surround formats, Dolby Digital® 5.1 (also known as AC-3) features five full-frequency-range channels - left, center and right front, plus left and right rear-and a sixth channel for Low Frequency Effects (bass). Digital surround sound is often referred to as "5.1"; 5 main channels plus the Low Frequency Effects (LFE) channel. The advantages of digital 5.1 surround are more exciting surround effects and imaging with life-like impact and dynamic range. The difference in sound quality between Dolby Digital surround and Pro Logic surround is similar to the difference between CD and LP records.
Digital surround decoding systems such as Dolby Digital require digital sources such as a DVD disc or a Blu-Ray disc, which generally always carry a 5.1 channel Dolby Digital sound track. Dolby Digital is the established standard for home theatre, cinema and broadcast surround sound all around the world. All HD television broadcasts in the United States use Dolby Digital, and you will generally find Dolby Digital on all DVD discs and many Blu-Ray’s.
Dolby Digital EX took the 5.1 format one step further and incorporated an additional center channel for extra detail and surround sound effects. The latest format from Dolby is Dolby Digital Plus, which takes all of the core features of Dolby Digital 5.1 and allows for 7.1 channels as well as other features to improve the home surround sound experience. In your home theatre, the 7.1 format will feature an additional pair of speakers which are generally located on the sides of the room to further enhance the surround sound effect .
DTS: (Digital Theater Systems)
DTS (an acronym for Digital Theater Systems) is another digital surround 5.1 system that is a competitor to Dolby Digital. In order to play a DTS disc you must have a DTS surround processor. DTS first debuted in theatres in 1993 with the release of Jurassic Park. Since then they have gone on to work with almost all major consumer electronics companies and audio receiver manufacturers. In 2000 they introduce DTS-ES which features 6.1 channels of surround sound, and in 2004 DTS became a standard for both Blu-Ray discs. DTS NeoX 11.1 technology is the latest advance which adds height and width channels to make your home theatre experience even more immersive! DTS now has over 85% market share of HD and 3D entertainment. Ensuring that your home theatre receiver can process DTS signals will ensure compatibility with all major Blu-Ray releases.
THX - It's Not a Format
THX is a set of equipment specifications, compatible with all surround formats, intended to standardize the performance of any theater system. It does not compete in any way with Dolby Digital, DTS, Pro Logic or any other surround format. Software (movies) certified by THX may be played on any Dolby surround system and conversely, THX hardware can play all Dolby surround movie software whether or not it is THX certified. Home THX components are not necessarily better or worse than other products: they have simply earned THX approval by conforming to all THX-mandated specifications. Once the product has been submitted to Lucasfilm, LTD (the company that developed and licenses the THX standard) and passed a battery of tests, it can wear a "THX Approved" badge. In order to be a true THX system, all the audio components in that system--processor, amplifier, speakers and subwoofer--should be THX-approved. But that does not mean that THX and non THX components cannot be used together, they definitely can.
Digital Signal Processing (DSP)
Many surround receivers have "DSP" circuits that allow your surround system to mimic the acoustics of various locales such as concert hall, church, jazz club, etc. This allows you to adjust the sound settings to suit your environment and your tastes.
Hopefully, the above information helps you to choose the right Home Theatre Surround Sound receiver for you!