Confusion Begets Controversy

THX tries to define a listening (or, in the case of HDTVs, viewing) experience, rather than just a set of hardware specs. The very act of doing that makes the company somewhat controversial. On one side are the purists, who suggest that only high end products should be worthy of certification. Anything else – a THX logo on PC speakers, for example, is a sellout.

This is exacerbated by confusion between what THX tries to deliver and what any individual product might include in its feature set. Take A/V receivers: companies will bundle in extra features into THX Ultra2 certified receivers that actually have nothing to do with what the THX certification is meant to deliver. So users may assume those features are available on all products with that certification.

Then there’s confusion between audio and video certification. A good example of this was the recent controversy revolving round the Lexicon BD-30 high end Blu-ray player – which turns out to be a repurposed (and supposedly tweaked) Oppo BDP-83.

THX worked with both Oppo and Lexicon to ensure that the video capabilities met THX standards for video, including linearity of the signal and other factors. Oppo took some of what it learned, and worked that back into the original Oppo product. The Lexicon player was criticized not for just being an Oppo in Lexicon skin, but for not meeting THX audio standards… except that the player wasn’t certified for audio at all, just video.

But the very act of working with Lexicon to certify a product that was simply a repackaged and tweaked Oppo player left some analysts wondering what value THX really brings to the table. If, after that effort, all you need to do is upgrade to the latest Oppo firmware to get those video tweaks, what’s the value of the Lexicon player, other than a fancier external package and a logo? THX trades on its expertise in audio and video, but in the era of the Internet, being a company of high priests with secret sauce is a little more difficult.

All About Linearity

What does it mean when THX certifies an HDTV? There are already standards, like ATSC, for defining the HDTV signal. How the LCD, plasma or other HDTV tech interprets and plays back that signal is where THX comes in.

There are a key set of parameters that any good HDTV needs to hit in order to achieve maximum visual fidelity. Those parameters, however, don’t exist in a vacuum. Take the idea that an ideal panel will offer a gray scale color temperature of D6500. It’s easy to say that – but then you have to also add: D6500 throughout the brightness range. To achieve that linearity at D6500, THX mode dials down maximum brightness. So the tradeoff is a less bright image, which implies better light control in the room, versus a brighter image with a less linear signal.

Then there are more subjective areas, like contrast. Ideally, you do want as much contrast as possible. But having a 10,000:1 contrast ratio doesn’t mean you get great image quality, if the low range is still visibly gray and the high range is ridiculously bright.

When THX works with a panel provider, they specify settings that try to behave linearly – or at least, predictably – throughout the entire range required. You want a high contrast level, but not at the expense of a deep black level. But if hitting the deepest possible black level adversely affects pixel response time, then the HDTV may have to sacrifice a tiny bit of black level so the response time is fast enough.

Then you run into quirky behavior driven by the HDTV company’s need to compete on specsmanship. High refresh rates are a good example of this. You see quite a few HDTVs out today that advertise a “240Hz” or even “480Hz” response time. Those high refresh rates aren’t real – they’re interpolated. HDMI 1.3a and earlier don’t have the bandwidth to push very high refresh rates. Instead, the panel interpolates intermediate video frames to attain a high frame rate. This, in turn, can create artifacts or simply look odd, particularly with content originally shot on film at 24fps.

So when you enable THX mode in an HDTV, one thing that gets disabled is high frame rates, the idea being that film looks like it should.

Index In the Lab
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  • Patrick Wolf - Saturday, March 6, 2010 - link

    Setting your speakers to "Small" and having an 80Hz crossover is not just a THX recommendation. It's a universally accepted method for achieving proper calibration. The only time you set your speakers to "Large" is if you don't have a subwoofer. The auto-calibration on many AVR's often set this incorrectly.

    If your speakers do perform well at 50Hz, you can experiment with the crossover, but you need to set your speakers to "Small". However, your Studio 20's for example are actually rated ±2dB from 54Hz-22kHz. So your crossover should at least be 60Hz.
    Reply
  • SeanFowler - Saturday, March 6, 2010 - link

    I found that adding a subwoofer breathed new life into my Mission speakers, with the Missions set to small even though they're rated down to 40Hz.

    Just because speakers can handle low frequencies doesn't mean you should let them. My Missions were muddy in the midrange because the bass was swamping them.

    Removing that bass from them allows them to do a far better job with the midrange. Result, no muddiness.
    Reply
  • jkostans - Sunday, March 7, 2010 - link

    THX is a waste of time in consumer products, is doesn't mean anything about quality. The audio and video fields are full of smoke and mirrors. Actual calibrated measurements are the only thing you can trust. 90% of audiophiles are idiots that like to spend money and brag about how good their $10,000 interconnects sound. Subjective results are only as good as the person doing the testing. Reply
  • erple2 - Monday, March 8, 2010 - link

    I'd disagree with that. The highly trained ear can hear the difference in quality between the "$10,000 Interconnects", but the reality is that the vast majority of A/V snobs really aren't trained at all.

    The vast majority of people don't know what really does sound "good". Also, calibration is really only good to the consumer, not to the person doing the testing. In fact, you could easily argue that none of the calibration matters to anyone other than the consumer - if it doesn't look or sound good to the consumer, you're just wasting your time. Oh, and it has to actually look good, not look good because some calibration expert says so...
    Reply
  • jkostans - Monday, March 8, 2010 - link

    Just proved my point I think Reply
  • vol7ron - Saturday, March 6, 2010 - link

    Loyd,

    Nice read. I'd be interested to hear more about your "room acoustics" training and possibly setups to combat those problem with small spaces, or worse, small spaces with high ceilings.

    Thanks for the info, I like the breadth of Anandtech's content lately. Not just procs and video cards, but more.

    vol7ron
    Reply
  • gmallen - Saturday, March 6, 2010 - link

    Nice explanation of THX and the lab processes behind the logo. The usual top quality from one of the best writers in the field.
    I consider myself a pretty average A/V buyer; I am not confused at all by the various THX standards, nor by the feature set of a particular product. THX is one thing and feature set is another. Read the literature for the models under consideration, and decide away.
    As for the LCD certification, my local high-end A/V store has a fairly good viewing set-up. The side-by-side comparison of the same model with THX turned on and off shows clearly the superior picture quality of the certification mode. Even sports looks better, to these eyes.
    I conclude that, for me, THX certification in both audio and video is a valuable factor in selecting new products.
    Reply
  • DirtFace - Saturday, March 6, 2010 - link

    When I think of THX I think of George Lucas. And when I think of George Lucas nowadays, the last thing on my mind is quality. Reply
  • erple2 - Monday, March 8, 2010 - link

    Don't confuse Quality Hardware with Quality Content. The former, I think that George Lucas has done some rather impressive (positive) things with. The latter, well, I point you to the Teen Angst riddled shlock of Annakin Skywalker as portrayed by Hayden Christensen (caveat - I was over 30 when those movies came out).

    While the movies were terrible to experience in a language I can speak and understand, the visual and audio splendor I thought was extremely high quality. All of the mechanics of the films were excellent. The other half of my brain, however, died a little watching them.
    Reply
  • erple2 - Monday, March 8, 2010 - link

    Don't confuse Quality Hardware with Quality Content. The former, I think that George Lucas has done some rather impressive (positive) things with. The latter, well, I point you to the Teen Angst riddled shlock of Annakin Skywalker as portrayed by Hayden Christensen (caveat - I was over 30 when those movies came out).

    While the movies were terrible to experience in a language I can speak and understand, the visual and audio splendor I thought was extremely high quality. All of the mechanics of the films were excellent. The other half of my brain, however, died a little watching them.
    Reply

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