THE PATH TO THX SURROUND EX by Shane Buettner

Before We Begin...

Essentially, as THX Surround EX simply requires some additional matrix decoding applied to the discrete left and right surround channels of THX-EX encoded 5.1 channel soundtracks (refer to our in-depth report if you have any questions.) Short of your processor manufacturer offering a THX-EX upgrade (like my Lexicon MC-1, click here for full upgrade procedural write-up) or just going out and buying a processor with THX-EX integrated, there are a few approaches that we're going to cover here that will decode THX Surround EX material. Before I get on to some of those, you may want to read a report by Dan Ramer on a do-it-yourself option for decoding THX-EX soundtracks using a good old-fashioned Dolby Surround decoder that you may have out in the closet and forgotten about.

THX Surround EX Upgrades and Integrated Options

At least initially, THX Surround EX will be available exclusively in THX Ultra Certified equipment. Existing Lexicon MC-1 and DC-2 processors can be upgraded to THX Surround EX for $300 (existing MC-1 owners are being offered an introductory upgrade price of $100) and both processors are now shipping with THX-EX integrated at no extra cost. JBL's SDP 3 (which is built by Lexicon) Onkyo Integra Research's RDC-7, and Mark Levinson's No. 40 will include THX-EX. I would consider it likely that any manufacturers who are current THX Ultra licensee will give strong consideration to incorporating THX-EX into upcoming THX Ultra products.

Advantages to integrated THX-EX processors like those mentioned above include more advanced bass management options as well as independent time delays for the back surround left and back surround right channels. Also, THX-EX decoding will take place entirely in the digital domain with integrated products whereas the add-on devices available currently operate in the analog. Another potential advantage for THX-EX processors lies in the digital flag reported to be incorporated into future DD-EX encoded DVDs (Austin Powers does not have this flag, and it is unknown at this time if the Haunting will carry it.) A compatible THX-EX processor would auto-sense this flag and switch to THX-EX mode accordingly.

Rumors abound regarding some other manufacturers providing their own proprietary versions of EX processing in their processors and receivers, but I have not been able to substantiate any of this right now. I would note however, that technologically this shouldn't represent much of a challenge to manufacturers as the extra matrix decoding could be applied like any other DSP during post ûprocessing of 5.1 channel soundtracks.

ADA and a SMART Solution

Leading the add-on device approach to properly decoding DD-EX soundtracks are Audio Design Associates (ADA) and SMART Devices. Both obviously share the same goal, but their approaches differ significantly. I'll start with ADA for no better reason than they're first in the alphabet (such decisions are hard to comprehend for those who don't make their living with the printed word.)

ADA has perhaps the most comprehensive solution in that their two processors, in conjunction with one another if necessary or desired, will turn any existing setup into one that will decode DD-EX soundtracks. The $499 ADA 6.1 Surround unit offers simple bass management and can be used with an additional power amplifier(s) and speakers and with any 5.1 surround processor that has preamp line level outputs for the left and right surround channels. You would simply connect these line level outputs to the designated inputs on the ADA 6.1, and from there to the power amplifiers for the surround left and right and back surround speakers, or back surround speaker if you choose to use only one speaker for the back surround channel. Very simple.

Receivers are another story, and here's where the options add up. The first possibility is that you use a 5.1 receiver that has preamp outputs for the left and right surround channel. You could use the ADA 6.1 with the ADA AMPx4 ($399,) a four channel power amplifier. You would connect the left and right surround outputs to the ADA 6.1, from there you would go into the Ampx4 and out to your left and right surround speakers as well as your back surround speakers (or speaker.) In this setup the Ampx4 powers all of your surround speakers, left and right surround plus back surround speakers.

Where the ADA 6.1 and Ampx4 becomes Universal among 5.1 receivers is that the Ampx4 is also a "surround speaker to line converter." This means if all you have coming out of your 5.1 receiver is speaker cables, instead of connecting those speaker cables to your left and right surround speakers you would connect them to the Ampx4. The Ampx4 would then convert this speaker level signal into a line level (RCA) output signal that would be looped back into the 6.1 and then back again into the Ampx4 and out to your speakers. I know it seems like $900 is a lot of money for this upgrade and it is. But consider that official THX-EX is initially only going to be available in THX Ultra certified gear, which is expensive. THX-EX also has yet to be announced for any receiver at all. This upgrade might not be bad for someone who absolutely has to have it right now and doesn't want to buy an exotic (and expensive) processor. I would suggest that someone take a serious look at the link above to Dan Ramer's piece on the DIY solutions before spending this kind of dough on such a setup, however.

SMART's Circle Surround EX Jr, or CS-EX Jr, retails for $299. Like the ADA you connect the left and right surround outputs of your 5.1 receiver/processor to the unit, or speaker level if necessary (the speaker to line level converter here is integrated.) Here's where the similarities end. Unlike the ADA who has provisions in both of their devices for two speakers to be connected to reproduce the back surround channel, the CS-EX Jr is designed for a single back surround speaker. (If you really wanted two speakers to reproduce this channel you could simply use a Y-adapter at the output of the CS EX Jr.) The CS EX Jr also has no amplification either, nor a sister amplifier as ADA does, so you'll have to go to another manufacturer for that (which you're better off doing anyway.) The other difference is that the CS-EX Jr is based on Circle Surround matrix decoding, not Dolby Pro Logic. SMART claims their decoding maintains superior channel separation and a lower noise floor than Pro Logic based products. The claim here is that poorly designed analog Pro Logic decoders have a tendency to steer signals that are supposed to remain discrete in the left and right surrounds into the back surround channel when the signals are present at the same moment in time. SMART claims that conversely, their decoding keeps the left and right signals in tact at all times, simply "filling in" the surround back information when it's present.

I have no experience with either product at this point in time, but if that changes I will be sure to post my findings. If any of you have employed either of these solutions please write and share your thoughts.

Conclusions

The above, in conjunction with Dan's piece, is what I know of that's out there right now to decode DD-EX soundtracks. In the coming months we'll be sure to see more THX certified solutions, and probably more proprietary solutions from manufacturers who aren't THX licensees. How these unofficial (i.e., not THX) solutions As this information comes to light, I'll be sure to keep you informed.