Diablog: Go Pro

Hey, what happened?

Sorry. I was just going back and forth between surround and stereo.

It was as though the music just disappeared. Not entirely, but it became a shadow of its former self.

Ha. You're becoming a surround buff. Would you be surprised to learn we're listening to a CD?

It's one of those special CDs, right? Super Audio CD? Look, I'm actually starting to inhabit your insane dream world.

Actually it's just a regular two-channel CD.

You're up to your old tricks again. Taking something simple and making it more complicated. Still, I must admit it sounded better coming out of five speakers than it did out of two.

That's why I use the Dolby Pro Logic II music mode most of the time even when I'm listening to something recorded in stereo.

Oooh, talk Dolby to me. How many Dolbys are there in your system, anyway?

That is truly a loaded question and I'll get to it some other time. The one I'm talking about is the circuit that adapts two-channel music and movie sources to 5.1-channel surround. It was invented by Jim Fosgate, who lives in Utah and is truly one of the eccentric geniuses of our industry. He didn't design the original Pro Logic, which is strictly for movies, but he invented a new way of processing two channels into five.

I must admit it works. What's Jim like? It's rare for you to actually bring up a human being.

A quiet but intense man, soft-spoken and circumspect. The idea for DPLII came to him in a dream. Then he spent months working it out on paper. Then he sold it to the Dolby people. They had to run their supercomputers 24 hours a day for three months to digitize the analog circuit that Jim's mind created organically.

Sounds expensive. Is this some kind of high-end gear we're listening to?

Actually you can get Dolby Pro Logic II in pretty much any new model of surround receiver sold these days. It's in everything, even most HTIB systems. For manufacturers and consumers alike, that's the advantage of doing business with Dolby -- the company is a credible standard setter and its surround formats are universal. There are other processing modes from other companies that do the same thing but I like DPLII best because it has the most natural sound. Same feel as the stereo original, except better. And I can adjust it.

Must you?

Well, at least the first time you set up a system, it's a good idea. DPLII lets you adjust the side-to-side balance, concentrating the sound in the front center speaker or moving it off to the sides, so you needn't depend too heavily on a nonmatching center speaker if you don't want to. Then there's a front-to-back adjustment. You want that to send just enough information to the surround channels to sweeten the sound -- not enough to become intrusive. In both cases, I usually go for middle settings, and even you admit to liking the results.

Yes. I do. Now shut up and put Norah Jones back on. In Jim Dolby or whatever it is.

We'll turn you into an audiophile yet.

Mark Fleischmann is the author of the annually updated book Practical Home Theater. For links to the latest edition, visit www.quietriverpress.com.

Harold Wheeler's picture

Does DPL II perform differently on different equipment? (Sorry if this sounds like a stupid quesion.) I have noticed that my son's $250 receiver seems to create a better surround image than my $2200 processor.

Mark's picture

The basic Dolby-licensed circuit follows Dolby-dictated parameters though the specific piece of silicon used to implement it may vary in performance (MIPS, resolution, etc). Some of the adjustment options may not be in all DPLII gear. It's possible that you and your son are not using the same center-width and front-to-back settings.

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