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Dolby Pro Logic IIz vs. Audyssey DSX vs. DTS

September 23, 2009 By Geoffrey Morrison

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The demo room/lab at Dolby’s Potrero Avenue building was decked out with tons of speakers and equipment. The laptop (bottom middle) allowed for instant switching between formats.
With a “basic” 7.1 height setup the surround back channels are ditched in favor of front height channels mounted high as possible on the front wall. Dolby's ultimate system is keeping the surround back channels and adding the height for a full 9.1 setup.

Wall of Sound: Three new surround formats from Audyssey, Dolby and DTS aim to bring your theater sound to a whole new dimension. Literally.

You want me to buy more speakers? Yeah, I get that. To be honest, that was my first thought when I heard about height speakers. Just a gimmick, right?

Well, to find out, I journeyed up and down the California coast visiting the headquarters of the formats’ creators.

Along the way, I learned a little something about height channels, and a little about myself.

Ha. Just kidding. But how funny would that article have been?

Why Height?
YDolby Pro Logic IIzamaha, for ages, has had height effect channels. These aren’t exactly what we’re talking about here.

Yamaha's height channels primarily added reverb to make your room sound like a concert hall; that kind of thing.

Generally, though, they were on to something. We humans have an incredible capacity to localize sound objects in front of us.

For most people, they can pinpoint a sound within a few degrees of accuracy. This diminishes significantly as the sound moves behind you (between 15 and 20 degrees of accuracy). Chalk this up to the hunter part of hunter/gatherer.

So adding more speakers up front makes sense: We’re more perceptive to changes there.

Audyssey DSXFrom a pure logistic standpoint, this is beneficial as well. It’s a lot easier to convince your spouse to run a few more wires up the front wall behind the TV than running long cables somewhere behind the sofa (if you even can).

So Audyssey, Dolby and DTS are all talking height, and in one case, width. I had the idea to go to the source and hear these formats at each company—a sort of “best case scenario.”

If I couldn’t be convinced at that level, there was no way the end product in a regular room would be able to pull it off.


Wow, thanks for a GREAT, and eye opening article!
I bought Yamaha's RX V1 Flagship mainly because of Cinema DSP w/front effects channels. It is nice to see competing technology to the Yamaha. I don't want to give up my front effects speakers. I am leaning towards the Audyssey system, mainly because of the side effects channels. I have an old ADS digital time delay with side mounted speakers, and saw for myself how it can expand soundstages. Plus, and this may sound stupid, I TRUST Tomlinson Holman. I owned an old APT amp/pre amp from his old company APT. It had a real cool way to reduce separation between the two main stereo speakers w/o getting a HOLE in the middle! Tom, if you are listening, old friend, consider putting that feature BACK into your Audyssey surround circuit, save us from buying center channels , LOL

I would rather have 9.2 with 5 channels up front two at 90 at -120,-90, -60, -30, 0 (=Center), 30, 60, 90 and 120 degree angle around the room :)

Geoffrey, I love your articles as well. It's not that your on the cusp of a new technology or write it well in layman's terms. Many do that. It's your refusal to be convinced by smoke and mirrors. The no-nonsense approach. Is it good or is it marketing? And some humor thrown in. I actually read another article you wrote on Laserview from April of last year and was impressed enough to click your name to find a follow-up article. I wasn't successful, but this article is amazing. I didn't know these were in the works. I'll be coming back to read more from your articles so I don't miss out. Keep up the good work. :)

Tim Bogle

Anon, no where did he say 7.1 back channels are a waste. YOU made that up and it's misleading as it suggest the article states your opinion. It does not.

We have demo rooms with both 5.1 and 7.1. NO ONE prefers the 5.1 over 7.1 EVER. You could be the first though, LOL. So, as far as our customers are concerned, 7.1 has value.

Now, to add the lastest configs! Cant wait to test.

I completely agree that the back channels added with 7.1 are a complete waste. I am glad to see that more sensible work is now being done with DSX and PL2z. It sounds like Audyssey DSX is the best way to go giving you the option for both width and height.

Love your articles!

Jay Garbutt

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