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To THX, or Not to THX? (1 Viewer)

AllenLC

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Feb 26, 2003
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I am running Onkyo's 800 series Receiver & DVD player through the larger of the QX line of Dahlquist speakers.
I am not convinced THX is such a big deal. I have been experimenting with the THX mode and it always sounds like someone tossed a blanket over my system.
I am VERY happy with my setup but I am finding the THX mode useless. I even a complaintif comment stating it means "TURN" around and "HEAD" for the "EXIT".
I did not purchase the Onkyo for the THX certification. I'm glad.
Can someone explain to me what is supposed to be happening when one selects the THX mode?
 

ChrisWiggles

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Aug 19, 2002
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Hmm. I've never heard that much of a change. THX is mainly a certification that prodct "x" provides a certain amount of performance, e.g. in speakers flat response and some dispersion characteristics, etc., and in amps so much power per channel yadda yadda. Bundled with the certification were features that needed to be included, and things like "adaptive decorrelation" are now outdated, what with PLII and DD all over the place. Still there is one main feature that THX does provide, besides the certification that is quite useful, which is RE-EQ. This feature ramps down the highs that are mixed "hot" because of the characteristics of theaters that tend to attenuate the high frequencies. YOur home though most likely is flat, or even reflective/echoey and ramps up the highs (in the room), so the highs can get quite bad, what with the added highs that have not been corrected for from the theater. This might be causing the muffled effect you describe. Some movies, though already have this equalization applied when it is put on DVD, so you would want this feature turned off on those movies. Some should be used with this feature on. This feature is now pretty widespdread, with lots of other names, Cinema EQ, or Movie EQ, or some such thing, on non-THX units.

The merits of THX have been discussed pretty extensively, and I'm of the opinion that it doesn't really mean for much anymore, the features are either not really features(outdated) or widely available anyway and the certification, while good, is not always telling of the products quality. There are some bad products with the THX sticker, and many VERY good products without it. If you enjoy it without the THX mode engaged, then don't use it. I am a little worried that you describe such a difference, because any difference should be very slight indeed.
 

AllenLC

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Feb 26, 2003
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Thank you, That Clears Things Up. I'll put you at ease a bit and say It is a very thin blanket. I should know to be less dramatic and more accurate in my inquiry posts. You good folks take the time to respond and should not be led a stray by over statments. And I Thank You.
After reading your reply I did some more manual reading and experimental listening and I believe what I am describing is the EQ effects you speak of. Where it levels out or decreases the differences in background and forground sound. There is even a setting to take out some of the "brightness" that is mixed for theaters that might be overwhelming in the home setting. Another setting is called "Night Time". It is so some of the more soft volume dialog can be heard better without raising the volume level and disturbing the neighbors or such.
 

ChrisWiggles

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Yes the night mode is, I THINK a Dolby Digital option that has nothing to do with THX. Perhaps THX has something like this, but I'm not aware of it. It's standard(I think?) for DD, and basically it limits the peak volumes, and brings up the softer parts. Basically it compresses the dynamic extremes, because DVDs have huge swings in volumes from the quiet dialoges to the loudest explosions, so in order for the dialog to be intelligible, you need to turn it up to a level where when the movie gets really loud when those action scenes come. So during nigthtime, if you don't want to wake up other people in the house or whatnot, you'd have to keep fiddling with the volume so you can understand the movie yet not wake everyone up. Basically it does this automatically, so the volume swings are much less. These are all options that you should be able to turn off even when you're in THX mode.
 

Adam Barratt

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Dynamic range control comes as a standard feature on all Dolby Digital decoders. Some processors include global dynamic range controls that also affect DTS audio, but this is fairly uncommon.

THX re-equalisation is designed to eliminate the treble boost ('X-Curve') applied to theatrical soundtracks. This boost is designed to compensate for the loss of high frequency information at the distances most listeners sit from a theatre's speakers. THX's feature attenuates frequencies above 2kHz and is often quite noticeable, and can certainly be perceived as having a 'muffling' effect.

Whether a soundtrack actually needs this attenuation varies from film to film. Some newer discs include a 'near-field' mix that compensates for this high-frequency boost at the source, rendering THX re-equalisation unnecessary. Some soundtracks are very harsh, and may be presented on DVD with the X-Curve boost fully intact, and therefore benefit from THX re-equalisation (or other forms of generic equalisation). The only way to know whether the high-frequency roll-off is needed is to listen and experiment.

I personally feel the attenuation can be a little excessive and is applied at unnecessarily low frequencies. However, results are highly dependent on the inherent characteristics of the amplifier and speakers used, and the listening environment.

Adam
 

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