Axiom Home Page Forums General Discussion Home Theater I'm Confused--Dolby? THX? Pro Logic IIx? EX?

What does it do ? I assume it's "stereo to surround" processing since I've never seen anything "encoded in THX"...

Is there a button for it or something ?

Usually. I'm not sure what it does, as I don't own a THX receiver.

John (and Sparky). This should answer some of your questions.

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I'm not overly fond of DSPs in any case. Given that, I use DTS:Neo6 for TV watching, so go fig.

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Same here... on both accounts... watch stereo (Dolby Digital - have digital cable) program sources in Neo6 Cinema for television and Neo6 Music (pans the centre wider) for music channels, etc.

Bren R.

THX....Besides being a certification which also will do post production automatically, it is also a DSP as mentioned. There are tons of movies that have THX encoding listed on them. Use it on these movies, and your amp will switch to THX-EX(if DD also). This is a tremendous choice for those THX encoded dvd's

That article that Jack linked to explained what I was referring to.

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I did hear that there is some sort of high end roll off (or enhancement, maybe?) specified by the THX standard.

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"Re-Equalization generates a slight roll-off of the high-frequencies in movie audio to compensate for an artificially boosted high frequency used due to movie theater acoustics. Movie theaters roll-off the highs slightly due their design so a little high frequency signal boost is applied to compensate, however, that boost is not need in a home theater resulting in an overly bright sound."

I think this is the only audible difference between THX and DD.

Just a quick comment on ProLogic II. I would disagree that you need a 6.1 or 7.1 set up to benefit from this. My kids love it when I pop in one of their pop/dance/house thumping CDs (2 channel) and I set the receiver on Pro Logic II or DTS Neo 6. Even though I have a 5.1 set up, the sound is a nice improvement over the 2 channel version.

So I would say that even with a 5.1 set up you will hear a nice, positive impact using Pro Logic II or DTS Neo 6.

Personally, I LOVE DTS. I have been using DTS for about 6-7 years, back when not many people knew what it was, so I am a little partial to the DTS Neo.

As for THX, it is supposed to be just a certification, like other have said, of a certain level of ability for a piece of equipment to meet some fiarly strict (depending on the level of THX - Select, Ultra, Ultra2) guidelines in that equipment's (receiver, speakers, and so on) ability to reproduce sound. With that said, you will find some receivers that have a THX Cinema (or something similar) DSP mode. I have not looked to see what benefit it has being a DSP mode, but if the hardware can handle THX, it should be able to reproduce a "fuller" sound spectrum than a non-THX piece of hardware. I think that the THX DSP mode just tried to compensate for sound nuances that are often lost in the recording, or in the average home set up. To me, the THX DSP is just one system's estimate of what you may want to hear. I like the more "true" modes like Dolby Digital, and DTS for movies, although like I mentioned above, I do use some others to create simulated sound for my center, rear, and sub channels.

Last note, you should get something that can handle 7.1 and DTS (Dolby Digital is always included, and DTS is there on any good quality receiver, and on some cheap junk). THX will be there if you start getting into the $500+ market for a receiver. Not all will have it at that price, but you will start to see it.

Since I was starting from scratch, I went with a THX Select receiver that could handle 7.1 and DTS. I figured if I was finally getting some nice speakers like Axioms, I should have a nice receiver too, and the THX certification just means a little piece of mind to me in sound quality.

Now, you could go all out and get THX certified speakers too, but why would you want to with great products like Axioms.

THX Surround is closely related to Dolby Digital...

http://www.thx.com/mod/techlib/surroundEx.html?print=1

...so I guess technically it is a format. I have seen some AV receivers with the THX Surround logo (I believe it was a Kenwood). Whether or not there's a difference between the two, I don't know.

nickbuol Wrote:

Personally, I LOVE DTS. I have been using DTS for about 6-7 years, back when not many people knew what it was, so I am a little partial to the DTS Neo.
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I'm in the same boat. I used to surf the DTS website and special order DVDs that were formatted in DTS that weren't being sold in stores. I remember getting Saving Private Ryan in the mail and testing it out in both DD and DTS and the difference was HUGE!!!

As asked earlier, the difference B/W DD and DTS is the compression ratio. DTS provides higher fidelity than DD because the format only uses 1/16th compression whereas DD uses 1/4th compression. That is also why when you start a movie in DTS, you have to turn down the volume because it plays much louder. The lower compression ratio as explains why earlier DVDs formatted in DTS did not include any extras due to lack of disk space, but that was years ago and things are different now.

To this day, I look on the back of a DVD to see if it was formatted in DTS and if it was, it is a HUGE purchasing criteria, even if I wasn't necessarily interested in the content of the movie.

The Eagles "Hell Freezes Over" DTS DVD is a GREAT DVD to showcase your system.

DTS all the way...DD is too soft (fidelity wise) in comparison.

Now having said all of this, there are DTS mixed DVDs where the engineers did a horrible job of mixing and there is no real difference b/w either DD or DTS...these are usually the movies that include both a DD and DTS soundtrack.

Find the movies that are strictly DTS format and you can be rest assured that the mix will be amazing.

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As asked earlier, the difference B/W DD and DTS is the compression ratio. DTS provides higher fidelity than DD because the format only uses 1/16th compression whereas DD uses 1/4th compression.

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Actually, DTS tracks do use a higher bitrate than Dolby Digital - as for exact numbers, there are flavours of each and I've never really seen hard evidence (due to secrecy and closed doors in both camps) of exact numbers. Where did 1/16 and 1/4 come from? And what are those fractions of? Full 44.1K/16 PCM audio? DTS, Inc. and Dolby Labs use different models for compression - in the beginning, yes, DTS took up a lot more DVD real estate for its audio tracks, but most of what you have on the market now is the lower (some call it "half") bitrate DTS encoded audio stream. That way you don't have to give up the 4 audio programs of Director's Commentary and the 8 extra hours of footage shot "Behind the Scenes" with a DVX-100 so they can put a starburst on the front of the packaging that says "Wow! 8 Hours of Previously UNRELEASED Footage!"

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That is also why when you start a movie in DTS, you have to turn down the volume because it plays much louder.

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From an engineer's standpoint, a higher resolution digital audio stream cannot play any louder than a lower resolution stream. 0dBFS is the same digital ceiling (at which clipping occurs) whether the source material is raw PCM, DD, DTS or even a Windows Media file. DTS simply cannot play louder because it is DTS. It can be compressed - which reduces dynamic range in a recording in order to make the entire recording louder on average (This is a pretty good layman's description of compression)

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The lower compression ratio as explains why earlier DVDs formatted in DTS did not include any extras due to lack of disk space, but that was years ago and things are different now.

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This is pretty accurate, I'd add that DTS compression in the early days was the full bitrate flavour and dual-layer DVDs were not yet common.

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To this day, I look on the back of a DVD to see if it was formatted in DTS and if it was, it is a HUGE purchasing criteria, even if I wasn't necessarily interested in the content of the movie.

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Again, something that seems odd... not to poke a thumb in your eye, but I've never picked up a book and decided to read it based on the fact it was typeset in Caslon on Weyerhauser Cougar Opaque stock. For me, I guess the medium isn't the message, the message is the message.

Bren R.