THX question (1 Viewer)

[faraz]

From what I know about HT (which by the way is a lot less than some of the folks here)having a THX receiver will not do a whole lot of good unless your whole system meets the THX standard. This not only includes the equipment, but also the room and placement of equipment. Having one component of the whole system THX certified without the rest does not make a whole lot of sense to me.

 

[TonyTone]

...I took a look at the Kenwood VR-6050, VR-6060, and from the specs the only differences are that the 6060 has, Component Video Input/Output, Component Video Switching, Extra Digital Inputs(Optical), DTS ES, LCD Text Remote, Learning Remote, Extra S-Video Input/Output, S-Video Switching and THX Ultra...

Hmmm--I thought the only one out of the current VR-60x0 series that had THX was the VR-6070, and even then it's only THX Select, not Ultra...

 

[Matt AFA]

This is not what Re-EQ does. This takes the audio that was designed for a theater size and equalizes it for a standard size room. The treble push compensation for screen perforations is a very common misconception.

 

[Lewis Besze]

Let me re-phrase the point I am trying to make. THX defines what the standards are/should be. If an implementation fails to meet the standard, does that invalidate the standard? Or does that invalidate the implementation? It seems quite a few of you are basing your opinions on sub-par implementations.

Yes but they always part of the implementation as well.They don't have certify a product if they feel it's subpar.
Now if the standard falls below of what most people[HT nuts]belive as "reference",then we have a problem with the standards too.

 

[Michael Lee]

According to THX documentation, Matt AFA is right. Re-Equalization is to address the large room to small room transition. This is based on cinemas being an average room size of 60'x100'. This has to be reduced to the average room size of 16'x20' in the home. Psychoacoustically, tests have shown that the perceived error is too bright. Re-Equalization reduces the higher frequencies slightly to compensate for the perceived error to achieve tonal balance in the smaller room. It says in bold print in the THX Training Program that the Re-EQ feature is NOT to simulate "Screen Loss". There is compensation circuitry in the movie theater sound system that corrects screen loss. So nothing has to be modified when it is put onto DVD in regards to screen perforations.

 

[RichardMA]

From what I know about HT (which by the way is a lot less than some of the folks here)having a THX receiver will not do a whole lot of good unless your whole system meets the THX standard.

This reminds me of people who think because they have
a Sony TV, they HAVE to have Sony speakers and a receiver
because they "match." Please.
-Rich

 

[Lewis Besze]

Re-Equalization is to address the large room to small room transition. This is based on cinemas being an average room size of 60'x100'. This has to be reduced to the average room size of 16'x20' in the home. Psychoacoustically, tests have shown that the perceived error is too bright. Re-Equalization reduces the higher frequencies slightly to compensate for the perceived error to achieve tonal balance in the smaller room. It says in bold print in the THX Training Program that the Re-EQ feature is NOT to simulate "Screen Loss". There is compensation circuitry in the movie theater sound system that corrects screen loss. So nothing has to be modified when it is put onto DVD in regards to screen perforations

Since we can't disengage RE-EQ from the rest of the postprocessing, it would be hard prove otherwise so one must rely on THX's word on this. But trying to "simulate" a smaller enviroment with a EQ curve is a quiet a longshot I think. The bottom line is the circuitry lowers the upper midrange and lower treble at certain frequencies.However as part of the post processing they also lower the levels a bit of the surrounds,which can make one percive as a smaller space since the soundfield "shrinks" by this.
There was a thread a while back and many THX pre/pro receiver users complained about that,though some disagreed.I guess each to his own.And yes many DVD are remixed with "nearfield" the most recent was the Lord Of The Rings,and look for BladeII as well.
Oh yeah none of them THX certified.

 

[Greg_R]

THX has divisions for software, HT hardware, commercial theaters, computer audio, & others. These are totally different and separate groups. Judging if THX hardware certification is worthwhile based on the THX Highlander DVD doesn't make sense.

As someone already mentioned, THX hardware is not just a badge. It has to pass rigorous testing and validation (from THX). I'm not just talking about amp power either... there are numerous decoding and processing checks as well. The total cost per unit is very small (reported to be under $5 per unit, i.e. little difference in cost).

On AVS there was a very interesting thread involving someone who was intimately involved with the development of various Lexicon & Tag pre/pros. That person stated that no matter how many checks they performed, THX's testing always found some other issue or potential improvement. It was also hinted that some high end manufacturers attempted to get certified and failed miserably (and didn't bother to fix the issues).

How many THX certified products have had actual bugs out of the box? I can't think of any. However, think of the other DVD players that can't play disc XYZ or a receiver with broken functions (numerous). Although I agree that THX doesn't mean perfection, it at least means the unit will work...

 

[Lewis Besze]

This reminds me of people who think because they havea Sony TV, they HAVE to have Sony speakers and a receiver
because they "match." Please.

I see where you coming from but THX maintains that only a complete THX system will give you all the "benefits" they preach about.I tend to agree with that, even though I'm not in their camp.

 

[GordonL]

Do I need to buy a complete Home THX System to get the benefits of Home THX Technologies?
No. Each Home THX Product; Controller, LCR Speaker, Surround Speaker, Subwoofer, Amplifier, Equalizer, Laser Disc Player, Interconnect and Speaker Wire, and Acoustically Transparent Screen solves specific problems in Home Cinema sound reproduction. You can use any Home THX product in any home theatre system. When used all together, these components work synergistically to produce an ultimate surround sound experience.

 

[Lewis Besze]

I don't believe that they knowingly certify products that are sub-par, which some of you seem to insinuate.

I didn't insinuate it either.
What happens some times though is that they involved in projects that's outcome is questionable at best,see the Highlander DVD/LD.
Of course THX software mission prerogative is,that it will look as best as it can, not necessarily the best compare to other titles.Which means if the source elements are less then stellar,then THX can't produce "miracles".
What I was try to say that THX should stay away from those projects,since it won't do good to anyone including themselves,but if they stay with it then face the "critics".

 

[Espen Braathen]

"Timbre matching?
This is my favorite.I guess the folks at THX realized that dipoles aren't exactly a good match for anything,due to it's unusual readiating pattern,the problem with this feature is,though that what is it trying to match it to?
Is the processor miraculously knows what kind of main speakers."
Timbre matching has NOTHING to do with dipole surrounds.
Timbre matching has NOTHING to do with the speakers at all.
The concept of timbre matching is entirely based on the physics of human hearing. Sounds coming from the sides will take on a brighter quality as the treble is radiated more directly into the ear. This is a natural effect, however since surround commonly relies on pans from front/rear and vice versa Tomlinson Holman found that the differences in tonal quality somewhat "confuses" the hearing system.
Consider a sound panned midway between front and surrounds. The location is supposed to be at the mid point, but the actual sound waves come from to different locations which each has a different tonal quality and this will effect the localization effect. Timbre matching neutralizes this effect, so that only the pan (level difference) itself is heard.
"Re-Eq does only adress the front channels."
This is wrong. Re-Eq is built into the final timbre matching curves according to Tomlinson Holman (in a private e-mail discussion I had on the subject). This can also be confirmed by measuring the frequency response of the surrounds and compare them to the curve in the THX patent document.
Of course, with Pro Logic this was never a problem due to the limited frequency response of the surround channel in Dolby Surround, however with THX 5.1 processing the surrounds are also equiped with a re-eq filter (of course the same filter can do both re-eq and timbre matching as a combined response curve).
--
Espen Braathen
WEB: Link Removed

 

[Espen Braathen]

"How many THX certified products have had actual bugs out of the box? I can't think of any. However, think of the other DVD players that can't play disc XYZ or a receiver with broken functions (numerous). Although I agree that THX doesn't mean perfection, it at least means the unit will work..."

Afaik, there has been several instances with "faulty" THX equipment. One was a THX receiver from Technics which obvioulsy did not meet any decent standards for signal/noise levels. However, this does not mean that the prototype sample sendt to Lucasfilm for evaluation was identical to the actual production units...

Another THX scam was docuemnted in STEREO REVIEW without reveling the name of the manufacturer; however after a production unit of a THX approved loudspeaker was sendt to Lucasfilm it was found that the manufacturer had changed the loudspeaker cross over in such a way that treble was emphasised with several dB's compred to the THX certified prototype used to aquire the licensee.

Afaik, there's nothing to stop a dishonest manufacture from making modifications to the actual production run of THX approved hardware. This could include anything from using cheaper parts, to actually modifing the unit.



Espen Braathen

 

[Espen Braathen]

"And yes many DVD are remixed with "nearfield" the most recent was the Lord Of The Rings,and look for BladeII as well."

Sure, nowadays some releases are re-mixed for home theater, this was not the cause when the Home THX program was launched in the 90's.

(I'm not entirely sure it's a good thing as Lord of the Rings basically has a TOTALY different soundtrack on the region 1 DVD compared to the theatrical mix. And for some reason the Lord of the Rings DVDs released outside of USA does in fact have the _original_ theatrical mix and not the MiCasa version...)

And many movies are not remixed. I would not think that the Star Wars movies i.e. would be remixed in such a way. The sound on Phantom Menace and Attcak of the Clones will undoubtfully benefit from full THX Surround EX processing...

Of couse, the recent THX Ultra2 standard features the "THX Ultra2 Music Mode" which can be used for soundtracks which don't need Re-Eq.


Espen Braathen

 

[Lewis Besze]

And for some reason the Lord of the Rings DVDs released outside of USA does in fact have the _original_ theatrical mix and not the MiCasa version...)

Good for US.

 

[Lewis Besze]

The concept of timbre matching is entirely based on the physics of human hearing. Sounds coming from the sides will take on a brighter quality as the treble is radiated more directly into the ear. This is a natural effect, however since surround commonly relies on pans from front/rear and vice versa Tomlinson Holman found that the differences in tonal quality somewhat "confuses" the hearing system.

Since THX mandates Dipole for surrounds how is the treble radiates more directly to the ear?
Now of course higher frequecies arrive first[smaller waves],but since the tweeter faces away and wired out of phase,this already "filters" alot of the "brighter" character out.
Now of course this doeasn't defuse the theory you provided[from THX],but raises a few questions,as how the "one size fits all solution" can deal with all the different equipment[mainly speakers],and accoustic properties.?

 

[Espen Braathen]

"Since THX mandates Dipole for surrounds how is the treble radiates more directly to the ear?"
The figure of eight radiation pattern often used to illustrate the THX dipole does not represent the actual radiation pattern in a meaningfull way. Sounds will also reflect "directly" from the side wall and towards the listener. Unfortunately I'm catching a plane in a few hours and can not elaborate further at this point.
Holman has a book which discusses dipoles vs direct radiating surrounds in more detail called "5.1 Channel Surround Sound: Up and Running":
http://www.amazon.com/exec/obidos/tg...books&n=507846
Personally I favor direct radiating surrounds.
For THX patents:
US5222059 Surround-sound system with motion picture soundtrack timbre correction, surround sound channel timbre correction, defined loudspeaker directionality, and reduced comb-filter effects.
(US5189703 Frequency response compensation for motion picture soundtrack x-curve equalization or for listener-perceived surround channel to main channel)
Also, this AES-paper (www.aes.org) descibes Holmans basic research into home theater:
"New Factors in Sound for Cinema and Television"
Preprint Number: 2945 Convention: 89 1990-09
AES Journal Vol:Issue: 39:7/8 Page: 529 Year: 1991
Author: Tomlinson Holman
Its available for 5 USD, or THX i San Rafael might be able to send you one for free.
Espen Braathen

 

[Lewis Besze]

Thanks for the info Espen,I'll check'em out!

Personally I favor direct radiating surrounds.

Well there is something we agree on!