High-Def Digest Chats with Dolby About 7.1 and 9.1 Surround

Posted Wed Aug 18, 2010 at 12:00 PM PDT by Mike Attebery

By Michael S. Palmer

Dolby Laboratories was on hand last Saturday night at the 'Dexter Season 4' Blu-ray premier to talk multi-channel surround sound.

Here's a quick round up of what's available now in your local cinema, and for your home theater.

Dolby 7.1 Surround

In an odd reversal of home theater helping to improve theatrical exhibition, Dolby reps explained their new Dolby 7.1 Surround system, which rolled out at cinemas earlier this summer in conjunction with the release of 'Toy Story 3.' Blu-ray and Dolby TrueHD have been capable of delivering 7.1 in the home since 2006, but 8-channel sound in the cinema utilizing four discrete rear channels is surprisingly brand new. Yes, Sony's SDDS is an 8-channel format and has been in select theaters since 1993, but SDDS has five front channels, and only two rears just like Dolby Digital and DTS. Have a look the next time you're at the movies. There may be upwards of 15 to 20 speakers around you at your local megaplex, but it's still only two channels, Left Surround and Right Surround.

At present, most films (and now TV shows like 'Dexter') are mixed for a 5.1 theatrical, broadcast, and home entertainment releases. According to Dolby, despite some Blu-rays featuring 7.1 soundtracks, what 7.1 owners have been experiencing thus far is more akin to an expanded 5.1 mix; similar to the results of using products like Dolby Pro Logic IIx or IIz. Meaning, the four rear channels aren't quite as specific, or discrete, as they can or should be; the two extra channels are simply extrapolated, or split from the original two channel rears and encoded discretely for the Blu-ray.

Dolby 7.1 Surround came about when Disney/Pixar was preparing 'Toy Story 3'. They approached Dolby because they wanted to ensure theatrical surround sound was keeping up with visual technological advances like 3D and digital projection. The trick was to create a significant, immersive upgrade without needing time-consuming and cost-prohibitive construction. With Dolby 7.1 Surround, cinema goers get two new channels (in addition to the standard Front Right, Center, Front Left, Left Surround, and Right Surround): Back Surround Left and Back Surround Right. Exhibitors, depending on the age of their surround sound processors, simply need a firmware upgrade and to change a few wires.

'Toy Story 3' is the first theatrical movie to use the new 7.1 format -- the first movie designed and mixed with 7.1 in mind from the gournd up -- and therefore, when it comes home on November 2, 'Toy Story 3' will be the first true 7.1 Blu-ray release (not adjusted after the fact for home video, and only ironically available via a 7.1 DTS-MA track).

Dolby is currently working with theater chains to retrofit existing cinemas with the new format. Click here to find out where you can experience Dolby 7.1 Surround in your area. Let us know in the forums if you saw 'Toy Story 3' in an upgraded theater with the above embedded trailer and tell us what you think.

Dolby Pro Logic IIz

We spoke about Pro Logic IIx and IIz with Dolby last year, but it was fun to brush up on the subject again. For those who don't recall, Dolby Pro Logic IIx takes any stereo or 5.1 mix and upgrades it to 7.1 (Left, Center, Right, LFE, Left Surround, Back Surround Left, Right Surround, Back Surround Right).

Pro Logic IIz has a more interesting and complex pedigree. As described above both theatrically and in the home entertainment platform, 7.1 is an immersive sound environment, and will only become better as more and more films are mixed with that native capability. However, for many home theater fans, we're already pushing the limits of room logistics, and what our wives or girlfriends will tolerate in a decorative sense. The challenge for Dolby became how could they give an added value experience to all listeners, without adding another mandatory 100 feet of speaker cable to the back of the room (I'm of course paraphrasing and simplifying here).

To confront this challenge, they built the newest Pro Logic, IIz. One of Popular Science's "Best of What's New 2009", IIz is a 7.1 or optional 9.1 surround sound experience. In "7.1 Height" mode, home theater enthusiasts are able to take a 5.1 mix and add two more front "height" channels, a pair of satellite speakers, which should be placed at least a meter above the front channels at a 45 degree angle to give extra width. When getting a stereo, 5.1, or even 7.1 native source, IIz extracts "ambient sound and certain amorphous effects such as rain or wind" and directs them to these front height speakers. Dolby recommends Atlantic Technology (1400 SR-z, or other) for these height channels, and says one of the best demos for IIz is the rain in the opening moments of 'Ratatouille.'

With a 7.1 Pro Logic IIz AV receiver, customers have two options in how to run their system: 1) as a 5.1 plus the two height channels, or 2) as a traditional 7.1 system (four rear channels) without engaging the height channels.

But wait, there's more! Available on more advanced (read: more expensive) AVRs equipped with IIz is a drool-inducing 9.1 surround sound. This is the traditional 7.1 Surround Sound (four rear channels) plus the two height channels. Dolby is also hoping to expand IIz into the video gaming world; while it already works with any 5.1 input, including of course Dolby Digital Live, they're hoping that game developers can add in these ambient sounds, such as helicopters buzzing over head, to really place players into their gaming universes.

As a format, Dolby Pro Logic IIz has a different set of skills for every listener out there. Personally, I can't wait to try it out myself. If anyone already has IIz and height speakers running, please drop us a line in the forums and tell us what you think. IIz is available on many new AVRs from Denon, Onkyo, Sony, and Marantz. Click here for a quick Pro Logic IIz demo.

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Tags: Michael S. Palmer, Dolby, Dexter (all tags)