I felt as stupid as Dorothy must have felt near the end of The Wizard of Oz when Glinda, the Witch of the North, tells her that she always had the power to get back to Kansas. When I heard how Dolby Labs and Lucasfilm THX were teaming up to introduce a 6.1-channel sound system with the upcoming Star Wars: Episode I-The Phantom Menace , I realized instantly that I-and you, too-have long had the power to get similar 6.1-channel sound at home, and without ruby slippers. All that's needed are a Dolby Digital (DD) preamplifier, or a DD receiver that has multichannel line-level outputs, and a plain-jane, recently retired Dolby Pro Logic (DPL) receiver or amplifier. Hook them up precisely as in this diagram and prepare for some sonic wizardry. Pay real close attention to which signals are digital, which are analog, which ones go to the front speakers, and which go to the surrounds. To get 6.1 channels, all you have to do is pretend that the two decoded DD surround channels are quasi-Dolby Surround analog signals and "decode" them to three channels using a Dolby Pro Logic circuit switched to its "3 Stereo" mode. To get everything to work right, you'll have to follow a speaker-balancing routine that's a bit more complicated than with 5.1 channels. • First, set the DPL receiver to "3 Stereo" and balance the levels of the three surround speakers using the test-tone generator and the channel-level controls of the receiver. (To revert to standard 5.1-channel sound, just set the DPL receiver for normal stereo playback.) • Switch the DPL receiver to its CD input and set its volume control slightly higher than the setting you normally used when listening to CDs. Don't touch any level control on this receiver again!
• Turn on the DD preamp's test-tone generator and balance the three front and the two surround left/right speakers using the controls in the preamp (no sound should come from the center surround in this step). I used all dipole surrounds in my setup, with the center surround speaker turned sideways (firing up and down) and placed to the rear of the listening room up near the ceiling. The results I got ranged from stunning to barely different from a 5.1-channel setup, depending on the program. Any 5.1-channel soundtrack that either has sounds moving between the left/right surround speakers or deliberately places identical sounds in the two original surround channels will produce lots of action from the back. The most spectacular results I got were in the New York City sequences of Godzilla, where the sonic mayhem was as much front/back as left/right. In just about every case the results were superior to 5.1-channel playback because using a real center surround speaker won't produce an in-the-head image the way the two surrounds of a normal 5.1-channel system sometimes do. I also recommend trying a good 5.1-channel music DVD: John Fogerty's Premonition (Warner Reprise Video). This hookup will provide 6.1-channel sound only with true 5.1-channel soundtracks or music. It will not produce good results with material intended for Dolby Pro Logic decoding. On the other hand, the setup will produce excellent results if the DD component also has a good ambience-enhancement system for music. In my setup, I used a Sony TA-E9000ES preamp, and when I engaged its Church mode while playing Gregorian chant the sense of envelopment in 3-D was surprisingly cathedral-like. This is my favorite kind of audio discovery, one that makes me go through my collection to discover recordings that sound brand-new again. So while my hookup may not correspond in all details to what Dolby and THX have cooked up, it'll give you a foretaste of what 6.1 channels will sound like in a movie theater. It is often so good that I would consider any home theater claiming to be state of the art to be inadequate without 6.1-channel capability.
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