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
Comments Locked


View All Comments

  • Ram21 - Monday, March 8, 2010 - link

    I enjoyed this piece, excellent description of THX certifications.
  • cheinonen - Monday, March 8, 2010 - link

    As much as I am loathe to defend Lexicon and the whole Oppo debate, using this as an example for THX being good or bad, at least for the reasons people have been citing, is incorrect because:

    - Oppo didn't submit the player for THX certification, for whatever reason (cost, not caring about it, I don't know) so the Oppo can't be THX certified if you buy it from Oppo
    - Lexicon did submit it for THX certification, and since the Oppo is very well designed and can pass everything that THX needs for video certification, it can be THX certified when sold by Lexicon, but not by Oppo, since Lexicon paid the fee for testing and the label
    - It's not THX certified for the audio section, as people have found that the 80Hz crossover doesn't have the correct slopes or crossover point to fit the THX standard.
    - THX has nothing to do with Lexicon using the Oppo for their player, or what it sells for, and to say that THX shouldn't certify products that conforms to their specs because someone else designed part of it (which would eliminate most gear out there), or the price is too high, would remove most THX certifications out there.

    I'd also cross over those Studio 20's at around 60 Hz or so myself, since the driver is going to have to work much harder to go full range, and the receiver will be working harder than if it was passing that material off to a subwoofer. Also, you'll be missing out on most, if not all, information below 45Hz or so unless you have double bass turned on in your receiver (not the best idea).

    I have fronts that can run down to around 24Hz for their -3 db point and I still will cross them over at 40 Hz or so, to make it easier for the amp to drive them, and I have the option to run them full range (no sub) if I am passing in analog from a turntable or a CD player, which perhaps is how you'd want to run the Studio 20's.
  • queequeg99 - Tuesday, March 9, 2010 - link

    Is there any way to determine whether a THX product is certified for audio only or video only before a company is called out like Lexicon was? I just see the THX logo on the device itself and marketroid literature touting "THX certification." I don't recall seeing any marketing or sales information on the Lexicon or other products that makes the distinction that THX is now making.

    Given the strong audio features of this device, not being very clear about what is actually being certified is seriously misleading.
  • cjb110 - Monday, March 8, 2010 - link

    I remember choosing my first home cinema receiver when DVD's were first introduced. At the time there was a lot of forum chatter about THX certification, Yamaha's stance at the time was that they did as stringent as tests as THX, and therefore didn't see the need in upping the cost just for the badge.
    Ok that's could just be PR, but the 2nd comment from the same source also stated that THX is meant for home movies, not general purpose (ie stereo music playback).
    And they we're right, at the time Yamaha's were also considered the best for 2ch music AND movie viewing...the THX'd Denons were good for movie, and so so for music.

    Point is that THX emphasises the movie experiance, sometimes to the degredation of other uses of the equipment.
  • knutjb - Sunday, March 7, 2010 - link

    THX is a marketing label implying a certain level of quality. It really just means a given product meats a predefined set of measurements. Measurements don't necessarily mean it sounds or looks good.

    If you're looking at a monitor like you would watch a movie, in a darkened room without people interrupting every minute, you will likely find what works for you, label or not.

    Same goes for sound, I didn't like the THX settings. They sounded flat and thin to me. I experimented with different settings in the store to see how much latitude I would have at home. I ended up with different equipment than I thought I was going to buy. I have small speakers running on full size and I went through a number of subwoofer crossover settings to find the best blend for my room. If the sub is set too high it won't disappear and for me 80hz is like a flashing light. Knocked it down to 60hz and it all seams to blend much better.

    Like the author, experiment with your settings for both monitor and sound and you can get very good results without spending silly money.
  • jabber - Sunday, March 7, 2010 - link

    ....after the Lexicon/Oppo scandal a few weeks ago.

    Badge for sale!
  • cosmotic - Sunday, March 7, 2010 - link

    Is in no way consistent. Temperature, quantity, and taste all differ way too much.
  • shotage - Saturday, March 6, 2010 - link

    Thanks Loyd, this was a good read.

    I look forward to a few more articles touching on similar topics i.e. sound!

    Keep up the good work!
  • idealego - Saturday, March 6, 2010 - link

    "When THX certifies a piece of hardware – say, an A/V receiver – it works closely with the company building the receiver"

    THX might want people to think this, but there is a lot of evidence to suggest that this isn't true. For example, many products are THX certified by a company that simply rebadges the product, even though the original manufacturer was never involved in THX certification and continues to sell the product under their brand without THX certification.
  • queequeg99 - Saturday, March 6, 2010 - link

    After reading about all of the foolishness surrounding the THX certification of the new Lexicon BD player, I would be hesitant to pay any material premium for THX certified equipment.

Log in

Don't have an account? Sign up now