THX Question (1 Viewer)

[Jeff W.]

6.1 is great. Even on 5.1 soundtracks, the extra rear channel fills the rear space better. (You can force it into 6-channel mode even on 5.1 soundtracks). Plus you can use it for all-channel music or DTS Neo (whoa) surround modes.

Just one minor point though, there is no "7.1" format.. yet. Some people use 2 surround-back speakers, and use a receiver with 7 amps to power them, sometimes called a "7.1" receiver.. but there are only 6 seperate channels, so those 2 speakers operate in mono, basically.

 

[Bob McElfresh]

I'm not up on the genesis of this format. But here is what I know about the technology:

- The rear-center track for what is called "DolbyEX" is based on Dolby ProLogic. There is no separate rear-center channel. Instead, the L/R channels carry some sounds that are exactly 180 degrees out of phase. A ProLogic decoder looks for these and if it finds them it strips them out of the L/R channels and sends them to a middle channel.

When The Phantom Menace came out, it had DolbyEx encoding. To extract the rear-center sounds (because nobody had DolbyEx receivers), people would drag out their old ProLogic receivers from the garage and use it to power 3 rear speakers. This would extract the rear-center sound to create a more complete surround experience.

So while Lucas/THX was the first to use it, the core technology is Dolby ProLogic.

I suspect there are some licence agreements/"Branding" that causes THX to be associated with DolbyEX. This may be the cause for the confusion.

 

[GordonL]

Jack,

You're missing my point. Joey six-pack doesn't want to know/care about the technical issues involved. So buying THX gives him some assurance that what he's buying meets some standard of performance.
Technically true, I guess. However, THX and Lexicon's Logic7 uses decorrelation in the rear channels to give you psuedo 7 channels. Close enough for me.

 

[JohnMW]

Bob, a quickGoogle Search seems to back up my statement about THX having it's hand in the development of Surround EX.

THX Surround EX has its roots in the Dolby Digital-Surround EX technology developed jointly by Lucasfilm THX and Dolby Laboratories. Gary Rydstrom, the Academy Award-winning Director of Creative Operations at Skywalker Sound, wanted more creative flexibility on soundtracks, including the ability to position sounds directly behind the audience.....

http://www.thx.com/mod/techlib/surroundEx.html

So many people keep stressing that THX is simply a certification and nothing more. Even the HTF primer seems to back up that claim. However it appears that this may not be the case. I'm no expert on the subject, but from the research I've done I now know that THX does more that "certify" HT Hardware & software.

 

[Jeff W.]

Show me a DVD with a "THX Surround EX" soundtrack.

T'aint none that I can find. It's either DD/DD-EX or DTS/DTS-ES.

 

[JohnMW]

Jeff, eventually Dolby licensed it (THX Surround EX) under it's own name. I think I stated that in my initial reply.

 

[Bob McElfresh]

Yes, but in the context of "Should I buy the equipment with the THX logo on it?" questions, most of the other stuff is irrevelant.

 

[Jeff W.]

Right, my point was you don't *need* the THX logo on anything. There is no "THX" format that you need your player/receiver/TV/toaster-oven to support. That's what confuses most newbies I think.. (and a lot of oldbies too)

 

[V JACKSON]

In a nutshell,THX Surround EX and Dolby Digital EX are the same thing. THX Surround EX came out first and then was licensed by Dolby as Dolby Digital EX, just as John said.
I have a THX-Ultra certified receiver but my speakers are not, because the speakers that sounded best to MY ears on music and HT, simply, were not certified. I consider them relatively high end speakers, and I still hear the difference in soundtrack quality with THX on and with it off regardless of my speakers. So no, I don't believe everything has to be THX certified, but ultimately, its up to you and your budget.

 

[Lewis Besze]

Yes more then likely,however changing out any speakers would result in change of sound too.
THX certified speakers usually have restricted vertical dispersion to minimize floor and ceiling "bounce" which THX feels smears detail and imaging.However many feels also that these speakers don't do to well on strictly music,or on dual duty.
IMO if you after the THX sound get the decoding device[receiver/ preamp] with THX and the speakers,and you get most out of it what THX advocate as the "THX sound".

 

[Kevin. W]

Equipment without the THX certification can still meet or beat the standard. Its a gimmick that some companies pay for to sell more equipment. One thing we all have to remember(don't know if its been mentioned) is that unless you room is setup to THX standards then all the THX equipment in the world won't do you any good.

Kevin

 

[ChrisWiggles]

Whoaaaaa there was some confusiong going on in this thread.

To be absolutely, totally, 100% thoroughly crystal clear:

THX is NOT a sound format. In *ANY* way, shape or form. Period.

"THX Surround EX" Is *NOT* a sound format. It is, as described, totally the same as Dolby Digital EX. This is a PROCESSING method to CREATE 6.1 from any 5.1 DVD.

SOME DVDs are expressly mixed with this in mind, and thus carry the DD EX label. This is STILL a 5.1 DVD. As for flags, yes there SHOULD be an EX flag which will trigger EX decoding automatically, but as we all know, often things are misflagged.



So that doesn't really make much sense...

EX is EX.

DTS-ES matrix works exactly the same way, and if I recall correctly, pays Dolby/THX royalties for the use of what is, in essence, pretty simple processing to create a rear center.

I don't bash THX for any particular reason, but nor do I ever pay attention to whether a component is THX certified. While THX certification carries with it some "features" such as RE-EQ, almost everything comes with these options anyway. As stated above, there are a few inferior, THX certified products, and there are MANY high-quality products that are NOT THX certified.

Bob mentioned DTS-Ex, which I take to be a typo. It is DTS-ES, as I mentioned, and comes in both matrixed (essentially the same as DD EX, except for DTS in 5.1), and discrete varieties. DTS-ES discrete is backward compatible, and contains the 6th channel discretely. No such 6.1 format exists for DD.

 

[Jack Shappa]

Gordon,

I didn't miss your point, but apparently you missed mine. I don't have an "issue" with Joe Six Pack not wanting to do research and just get something with a "quality badge" on it. Its his money. But you asserted there was NOTHING WRONG with that approach, and to me, simply buying something because it is "THX certified" is not the best way to go about buying your equipment.

- Jack

 

[Al_Swanson]

Not sure what ya'all are arguing about. There's some simple things here:
1) THX is a certification process. It's not a format or a recording/playback methodology.
2) THX certification has an intrinsic value, no matter how much the 'more sophisticated' (or whatever tag you wish to use - more informed, more....) want to disagree.
It's like ISO certification. You don't buy from an ISO certified shop cause their stuff is better. It may not be as good as a non-ISO shops stuff. You buy it cause ISO (or THX - and yes, I know it's not Thomas that comes out) certifies the product meets certain criteria.
Do you need THX? No. Does THX certification mean that one piece of your system will work better than others? The certification certainly won't do that, the quality of manufacter that it implies may.
Buying things because they are THX certified may not be the best approach to buying your HT gear, but having that badge as one of your criteria when shopping for gear is not a bad idea. Just like the ISO certification, you have some assurances as to the baseline with THX stuff.
No, I don't work for any of the above. My speakers are THX, nothing else I have is....I can't afford it....yet....
Bottom line - THX certification guarantees a certain level of performance. Nothing more, nothing less.

 

[JohnMW]

Absolutely!

 

[Wayne Bundrick]

No, THX is also a playback processing mode. It provides 1) Cinema Re-EQ which alters soundtrack equalization in an attempt to compensate the X-curve standard for theaters to something more suitable for living rooms; 2) timbre matching which attempts to compensate for the difference in timbre between having an array of surround speakers on the wall in a theater and having a single surround speaker in the corner of a living room; and 3) decorrelation for mono surround tracks which attempts to make the mono surround track sound more diffuse such as you would get from an array of speakers in the theater.

THX also has stiff requirements for bass management, in particular THX insists on the 80 Hz crossover. In this respect THX is more than just a certification process because passing the certification requires an indoctrination in the THX way of doing certain things.

 

[Kevin. W]

Before this gets out of hand below is take straight from the THX.com wesite FAQ's. Also checkout more info at

THX INFO

THX Home Theatre is the ultimate in sound for multi-channel home entertainment systems. The system incorporates a series of patented electronic and loudspeaker developments designed to reproduce all multi-channel sources accurately in the home.
The driving force behind its creation was the observation that conventional audio components could not accurately reproduce film soundtracks in the home environment as they were originally created by filmmakers. Two basic requirements were identified:

A need to correct the audible tonal and spatial errors caused by the playback of soundtracks designed in and for large theatres in the smaller environment of a home.
A need to more accurately reproduce the complex and competing sound fields present in multi-channel sound playback.
Originated by director George Lucas, the THX Home Theatre standard has a firm foundation in the production processes associated with all feature film material.

Is THX Home Theatre compatible with Dolby Digital and DTS?
Absolutely! The goal of THX Home Theatre is to accurately recreate the experience of the film mixing theatre. All mixing theatres are capable of creating both 4 and 5.1 channel mixes. The acoustics, equalization curves, and loudspeaker arrays used in a mixing theatre remain the same for a digital 5.1-channel soundtrack as they do for a 4-channel Dolby Surround soundtrack. THX Home Theatre technologies are needed to reproduce these movie soundtracks accurately.

Do THX Dipole Surrounds work with these 5.1 channel digital formats?
Yes. The Dipole Surrounds' design emulates the soundfield of an array of loudspeakers exactly as those found in mixing theatres and movie theatres. In movie theatres, these "surround arrays" provide a big surround sound experience. Because surround placement in the home is limited to a few speakers close to the listener, the THX Dipole Surround is the best way to provide a big surround experience. Sound effects and pans have correct directional cues, and surround ambiences are open and enveloping. With the newer "split surround" formats it is even more important that surround cues and pans do not "collapse into a box".

Are THX Home Theatre speakers suitable for music listening?
Yes. The speakers in a THX Home Theatre system (both Ultra2 and Select) are optimized for multi-channel sound (4 or 5.1 channels), so you get better imaging and clarity from the front speakers, and more envelopment from the surround speakers. Both of these benefits are ideal for music reproduction.

What are the benefits from THX Home Theatre on 4 Channel or Digital 5.1 Channel Soundtracks?
You hear a more natural tonal balance. Many motion pictures reproduced through typical home audio systems will sound unnaturally bright.
The dialogue will be more intelligible. In 5.1 channel mixes, all 5 main channels can be operating at once. With dense sound mixes, action effects can seriously mask subtle dialogue. In THX Home Theatre, you hear dialogue more distinctly, even in sequences with loud or complex sound effects.
You experience a more uniform sound envelope. The front and surround soundfields merge, seamlessly putting you into the motion picture.
Sound localization is more accurate and focused. You notice that sound closely follows the action on the screen.
You experience all of the dynamic range and frequency response of a motion picture soundtrack without distortion or other artifacts.
The system effortlessly reproduces the bottom two octaves of bass with clarity and precision.
What components comprise a THX Home Theatre System?
To accurately translate a motion picture soundtrack for a home environment, three THX Home Theatre product groups are necessary.
THX Controller - includes multi-channel circuitry and the necessary electronic enhancements (Re-equalizationTM, Timbre MatchingTM, DecorrelationTM, and more) to successfully render the film sound experience in a home.
THX Loudspeakers – Six speakers (Left, Center, Right, Left Surround, Right Surround, and Subwoofer) reproduce the clarity, localization, spaciousness, and timbre found in complex multi-channel soundfields. The Front speakers contribute proper tonal balance, intelligibility, and imaging, while the Surround speakers provide good envelopment and a sense of spaciousness.
THX Amplifiers - built and tested to exacting specifications for distortion, noise, stability, and dynamic power required in a multi-channel sound system.
Other categories of THX Home Theatre products include:
THX Room Equalizer - corrects room acoustic problems. While not always necessary for best performance, a Home THX Equalizer can significantly improve the perceived frequency response and timbral accuracy of a system.
THX Acoustically Transparent Projection Screen - gives top-notch front-projection video performance and yet permits behind-screen speaker placement with no audio degradation.
THX DVD Player - performs to the highest audio and video standards. Consumers can expect to see improved resolution and color fidelity, finer detail, and reduced noise on any digital video disc. In addition, the audio performance of a THX DVD player will please the most demanding audiophile. THX DVD Players include the ability to provide a direct output for multi-channel digital audio, such as Dolby Digital and DTS.
THX Interconnect Cables - built to exacting specifications which ensure the truest audio performance and avoid sound coloration, even over the large distances often needed in home theatre set-ups.

I’ve heard that 5 matched loudspeakers are recommended for 5.1. Why does THX recommend something different?
In a movie theatre, the surround speakers and the front speakers are different because they do different jobs. The front speakers deliver clear dialogue and localized sound that matches the picture. The surround speakers create diffuse and enveloping surround ambiences with occasional effects like pans or "fly-overs."
If you build a 5.1 channel home theatre system using conventional loudspeakers, you’ll need a minimum of 5 matched speakers plus a subwoofer for accurate sound reproduction. By contrast, THX Home Theatre speakers have multi-channel sound capabilities built in. THX LCR Speaker and THX Dipole Surround designs psychoacoustically match the best surround sound performance of a movie theatre or mixing stage. The THX subwoofer keeps the size of all of the speakers small while allowing for peak dynamic range and bass performance.

Do I need to buy a complete THX Home Theatre system to get the benefits of THX technologies?
Each THX Home Theatre component - Controller, LCR Speaker, Surround Speaker, Subwoofer, Amplifier, Equalizer, DVD Player, Interconnect and Speaker Wire, and Acoustically Transparent Screen - solves specific problems in Home Cinema sound reproduction. You can use any THX Home Theatre product in any home theatre system. When used all together, these components work synergistically to produce an ultimate surround sound experience.

What are the differences between the various price levels of THX Home Theatre products?
While THX Ltd provides production requirements and strict performance testing, each manufacturer brings their own perspective and expertise to the design and construction of their products. Some of the possible factors in product price differences are:
ability to play in very large rooms
additional DSP sound processing modes
exotic construction techniques and the use of more expensive parts or materials
complexity in design and construction
Customers can choose from a wide variety of products and manufacturers -- THX Certification guarantees these products which share a common purpose and design. THX Home Theatre products reflect the best multi-channel playback systems possible in each price range.

 

[Robert.CB]

Thank you all for all your replies.

I think that I am getting what THX is about. Basically, "the THX label" guarantees that that piece of equipment will perform as THX requires it to through processes that THX required it to have. But some other components may incorporate these processes that are not THX certified.

And with the 7.1 channels, the last two surround speakers actually play about the same thing. But there isn't a dvd that has a 7.1 sound track yet. 7.1 is achieved through through your equipment, but it's not really true 7.1. Is this correct?

To achieve a complete THX compliant home theater, you would have to basically have THX certified everything from your room to your components, which could be really costly.
So through learning and research I could achieve a home theater that sounds awesome to me without being real real real costly.

Am I on the right track?

 

[ChrisWiggles]

YES! Pretty decent summary.