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The Soul of Your System

Last month we discussed the importance of spending the lion’s share of your resources (meaning both time and money) on your speakers. That’s because they make the biggest difference in the sound of your system. You may choose a pair of speakers for a traditional, two-channel stereo system or you may purchase seven or more speakers for a full-blown A/V surround-sound system. Whatever your setup, you must choose your speakers based upon personal preference because speakers are the most subjective component in terms of sound.

After you have chosen the speakers that sound the best to you, you must now choose the best component to power them. This is the power-amp/pre-amp combination or having these components all in one chassis, the receiver.

Some audiophile purists maintain that separating the power amp, signal processing and AM/FM tuner stages into three discrete chassis yields the cleanest, most interference-free signal. But the vast majority of customers choose to incorporate power-amp, pre-amp and receiver into one. And with the incredible new surround-sound technology as well as a host of other amazing features, the new breed of A/V receivers delivers as good a sound as I’ve ever heard-and some of the flagship models are approaching audiophile prices, too.

The Ever-Evolving Surround-Sound Technology

Surround sound became famous thanks to Star Wars. George Lucas pioneered the art of choreographing the sound with the picture to deliver the most awesome action scenes. We all remember the Federation starships careening over our heads: not only did they shoot past us visually, but their screeching sound followed the picture precisely. Dolby Labs produced this effect, the same company that brought us noise reduction technology for tape recorders.

After the runaway success of surround-sound in the theaters, Dolby helped to bring surround-sound home and produced its first consumer-chip set, called Dolby Surround Sound. Dolby Surround Sound is an encode/decode system that requires “directions” for the sound to be encoded onto a video tape or laser disc during the video-editing process. The chip built into the receiver would then decode the sound upon playback, sending it to one of four different speakers throughout the room.

The first Dolby Surround Sound system, released in the 1980s, consisted of four speakers-two front main speakers, and two rear effect speakers. But in essence, Dolby Surround Sound was only a three-channel system. The rear-channel speakers each delivered the same monaural signal, so the effects could only move front to back with the picture, but not side to side. That was not the only deficiency with the original Dolby. The other issue was the movie’s dialog. In the theater, a discrete dialog channel was placed behind the screen so it seemed as though dialog was coming from the actors’ mouths. The original Dolby created a so-called phantom channel, which synthesized a center channel out of the left and right speakers. Unfortunately, this system sounded muffled, and tended to obscure the dialog, especially when it competed with other simultaneous sounds.

By the early 1990s, Dolby upgraded its three-channel surround-sound to a four-channel system called Dolby Pro Logic. Pro Logic utilized a center-channel speaker that sat atop your TV set and was much more effective for recreating realistic dialog. It also allowed the main speakers to work more efficiently by removing all dialog responsibilities and allowing them to focus on sound and music. Even though Pro Logic used five speakers, it is only a four-channel system since the rear-channel speakers are still mono.

Pro Logic’s problem was its wide performance variation, depending upon the brands and models of components that varied by manufacturer. These variations in movie theater sound systems’ quality, as well as those of home ones, caused George Lucas and his ace sound engineer, Thomlinson Holman, to create THX. THX is not a surround-sound format, but rather a strict set of standards set for Dolby Pro Logic. In order to become THX certified, receivers and processors have to deliver incredibly accurate sound measured by the signal-to-noise and distortion ratios, but also by a receiver’s ability to “steer” the sound from speaker to speaker accurately. The speakers also must conform to the same tough standards. Overall, THX surround-sound was the best available-and also the most expensive, costing up to 10 times the price of a normal Pro Logic system.

By the mid-1990s, Dolby advanced the cause again by delivering Dolby Digital. This system takes advantage of the cleanliness and accuracy of digital technology, ensuring a greater consistency between models than did the analog Pro Logic. Unlike the four-channel Pro Logic system, Dolby Digital is a full-blown, five-channel system delivering stereo, rear-effects speakers, allowing the effects to move from side to side instead of just from front to rear. Dolby Digital also boasts a dedicated low-frequency output specifically for a subwoofer. A subwoofer is a large speaker that delivers low bass sounds and adds another dimension of excitement to movies and music. This channel is of limited range and is thus referred to as the “.1” channel, making Dolby Digital a 5.1-channel surround-sound system.

The nice thing about Dolby Digital is the fact that it is a universal standard among all of the new digital delivery media including DVD, DIRECTV, DISH Network satellite systems and HDTV. Since nothing in the world of consumer electronics is easy, there are some wrinkles in the surround-sound fold. The first one is DTS, a competitor to Dolby Digital, backed in part by Steven Spielberg. This technology is designed for music and movies and boasts a better audiophile-type sound than Dolby Digital, which DTS claims doesn’t sound as good with music as DTS does. Although DTS has gotten decent support from the hardware companies, the music and movie studios haven’t really gotten behind the technology and there are not many titles available in DTS.

Another wrinkle is the recent addition of a 6.1-channel system from both Dolby and from DTS. The additional channel for both systems is a center channel in the rear. This adds another dimension of effects and, in essence, allows the viewer to localize a movie’s effects to the rear for enhanced performance. For this latest surround-sound enhancement, Dolby Labs has teamed up with THX to produce Dolby Digital EX. DTS also has a competing 6.1-channel technology called DTS ES. The future of 6.1 is still unclear, so stay tuned for details.

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