Sony MHC-GX25 The Sony Guide to Home Theater - Page 29

The next wave of home theater sound innovation came with the launch of digital distribution formats, including DVD, digital cable, DIRECTV digital satellite broadcasting and free, over-the-air digital television broadcasting. These digital media opened the door to digital surround sound. Dolby Laboratories answered with the Dolby Digital system. Compared to Dolby Pro Logic decoding, the Dolby Digital system has crucial advantages: ƒ Digital sound quality. The movie sound tracks now approach the sound quality of Compact Disc. You'll hear full frequency response, low noise and exceptional clarity. ƒ Discrete channels. Where the Dolby Pro Logic decoder must pull the four channels out of two stereo signals, the Dolby Digital system keeps every channel separate, or "discrete." ƒ More channels. Where the Dolby Pro Logic system has a single Surround channel, the Dolby Digital system delivers a separate channel to the Surround-Left and Surround-Right speakers. All told, there are 5.1 separate channels. That's five fullrange channels (Left, Center, Right, Surround-Left and Surround-Right), plus a Low Frequency Effects channel to drive the subwoofer. ƒ Low-Frequency Effects (LFE) channel. The human ear can't detect where lowfrequency bass is coming from. This "omnidirectional" quality of bass means that a single subwoofer can provide bass for an entire surround sound system. The subwoofer bass will blend with the full-range speakers for a dynamic, high-impact soundstage. The LFE channel is often called the "0.1" channel because the subwoofer handles roughly one-tenth the frequency range of the full-range channels. ƒ Scalability. While the Dolby Digital system is often called a 5.1-channel system, it can also support fewer channels, all the way down to mono, for movies and TV shows produced before the 1970s. Surround Sound Formats Since the acceptance of Dolby Digital encoding, the number of surround sound formats has continued to grow. But don't worry. Modern A/V receivers are good at automatically detecting the surround sound format and automatically applying the best available decoding. ƒ Dolby Digital® surround sound. This is the surround sound system used on most DVDs, on DIRECTV satellite broadcasts and on free, over-the-air High Definition TV broadcasts. You need a receiver with Dolby Digital decoding. ƒ Dolby Digital EX 6.1-channel sound. The new encoding format includes a matrix "Surround Back" channel. ƒ Dolby Pro Logic surround sound. This decoding is important because it works with the Dolby Stereo signals encoded into literally thousands of movies and a large The Sony Guide to Home Theater 29