What’s With All This Dolby Stuff?

Like many people in the audio industry, I?ve always assumed that people who are interested in surround sound will master its complexities?and I?ve disregarded everyone else. With audio-component sales plummeting, I now realize how arrogant that attitude was. Forgive me. I will try to do better.

Following are a few pointedly asked questions and relatively simple answers. It?s not a definitive surround primer but maybe it will blow away a few clouds of gloom and perplexity. I could have made it simpler?but I could also have made it more complicated. Maybe this will be a good starting point for many of you.

What?s with all this Dolby stuff?

The most crucial home surround formats are licensed by Dolby Labs. Ray Dolby got his start in noise-reduction systems for studio and home use (which is why your old audiocassette deck has a Dolby logo). Then he branched out into cinema and home surround standards, two of which you urgently need to know about.

Why not have just one surround standard?

Because you want your system to handle more than one kind of source material. And even if there were no format wars, you?d still need one surround standard to process surround signals and another to adapt stereo sources to surround.

So which are the two I need the most?

Dolby Digital, for DVDs and DTV broadcasts. And Dolby Pro Logic II, for anything with a two-channel soundtrack?CDs, MP3s, legacy video formats, analog TV broadcasts, etc.

My receiver has at least a dozen surround modes. Explain that, wise guy.

Dolby Digital and DTS both offer one format for 5.1-channel surround, another for 6.1-channel surround (which I deem useless), and another for stereo sources. That brings us up to six. The remainder are usually pointless DSP modes that receiver makers ladle on like disgusting canned gravy. You can safely ignore them.

Do I really need DTS? That?s not a Dolby, is it?

DTS is a soundtrack option on some DVDs. It?s also Dolby?s main standard-setting rival. The DTS people say their soundtracks sound better because they come at higher data rates. The Dolby people retort that their stuff sounds just as good at the same data rate and that squeezing two audio codecs onto a DVD starves picture quality. You could get along without DTS compatibility but receiver makers are afraid not to provide it. Frankly, I use it sometimes myself. My brain says ?there?s really not much difference? but my heart says ?if you obeyed your brain all the time, you?d still be a virgin.?

How does my receiver switch between them?

Automatically. If it detects a Dolby Digital signal, it plays Dolby Digital; if it detects DTS, it plays DTS. The catch is that you select between them on the disc menu. Most discs default to Dolby, either the 5.1-channel version (safe choice) or the two-channel version (switch to surround). Look for ?setup? or ?languages? or ?audio??if there?s a DTS soundtrack, you can select it there.

What if I want to play a stereo source, like a CD?

Your receiver detects the incoming stereo signal and defaults automatically to one of the formats that convert stereo to 5.1 (five speakers and subwoofer). See? Manufacturers do something right occasionally. I suggest the Dolby Pro Logic II music mode as your default choice. Other alternatives include DTS Neo:6, Circle Surround, and Logic 7 but I think DPLII best preserves the feel of the original stereo mix.

My receiver has three Dolby Pro Logic II modes. Which one should I pick?

The music mode is for CDs and other two-channel sources. The movie mode is for an ancient analog surround format buried in the two-channel tracks of legacy video formats and analog TV. The emulation mode mimics the original Dolby Pro Logic. You may have to select one for each receiver input. As a one-size-fits-all choice, try the music mode, which works best for music and adequately for movies, whereas the movie mode is best for movies but wretched for music. The emulation mode is antiquated and dispensable.

What if I?m using six or seven speakers?

Then you can play a limited number of DVD titles in 6.1-channel Dolby (EX) and DTS (ES). The same rules apply?pick one from the disc menu and the receiver will auto-select. Receivers with Dolby Pro Logic IIx will convert any stereo or 5.1 signal for your six or seven speakers.

Is THX better than Dolby?

THX is not a substitute for Dolby. It is mainly a set of performance benchmarks that ensures (among many other things) that THX-certified receivers and speakers will play loud and clean. It doesn?t replace Dolby or DTS?it just makes them perform to a loftier standard.

Do I need SACD and DVD-Audio?

Only if you want to collect music in a disc format that sounds better than CD. Both support surround and stereo and both sound fantastic. Check out the surround mixes of Pink Floyd?s Dark Side of the Moon on SACD and Steely Dan?s Everything Must Go on DVD-Audio. Contrary to rumor, these formats are not dead, though an unfortunate format war has slowed them down. I definitely recommend SACD to classical music lovers thanks to an ever-lengthening catalogue of surround releases from Telarc, PentaTone, and Sony Classical.

Make it easy for me. Tell me what to buy and how to use it.

Buy any surround receiver that does a good job of powering your speakers (I use a Rotel and also recommend Outlaw).

Buy any DVD player you want, but if you want to hear those Pink Floyd and Steely Dan surround mixes at their best, make sure it?s an SACD/DVD-Audio universal player.

Set the receiver?s surround default to the Dolby Pro Logic II or IIx music mode.

When playing a movie DVD, always select a surround soundtrack from the disc menu, though it doesn?t matter which one.

Now you?re in business. And look, I?m still under 1000 words. Woo-hoo!

Mark Fleischmann is the audio editor of Home Theater and the author of Practical Home Theater (http://www.quietriverpress.com/).

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