THX - seriously

[TroyD]

OK, attitudes in check fellas, I have some questions and obersvations about THX, I'm hoping that we can discuss like adults.

Granted, THX Cinema RE-EQ circuit tames the center down a little but remains sonically intact for the same dynamic as that of your mains which an eq can not do

Essentially, that says to me that the folks at THX believe that ALL soundtracks have incorrectly mastered center soundtracks. I think that is too generic of an assumption. If you are getting (in a non-THX environment) even SPL's, I don't see the benefit. Am I reading this wrong?

Now I believe a THX rated EQ should be USED with a THX processor to fully tune a room

Ok, if you got issues with room acoustics, OK. But what does a THX EQ offer that another that any other EQ doesn't? I don't believe that a THX badge on a piece of gear automatically makes it superior.


Now, as far as timbre matching on all the channels....'Rucy, you got some 'splaining to do. How is this possible? Are you saying that say you here a guy walking accross your rear soundstage (or front for that matter) that the actual soundtrack has a flaw in it that would change from one channel to another? How is this possible? It's the same sonic event that has been mastered onto different channels, I don't get how the timber changes.

Same thing with the phase correction. How do you do this via THX?
Does it come with a flunky that will invert your speaker wires as needed? "JUAN PHASE SHIFT! MUY PRONTO!!!"
I'm just saying, explain this to me, I don't understand how a THX processor does this.

Anywho....these are my thoughts and questions..

BDT

[RuSsMaN]

You forgot 'Adaptive Decorrelation'.

My Oink rec has THX Cinema Re-EQ, it does change the sound a bit (not for the better -imo), the manual says 'It scales down the soundtrack to better fit the average listening area'.

[TroyD]

so, it's sort of like Denon's 'dynamic correction' or whatever they call it. Which sucks.

yeah, if forgot 'Adaptive Decorrelation'. I don't have the foggiest idea what that could be.

BDT

[HBombToo]

Troy

Your impressions, comments and questions are well put and in line with my thinking on the matter. Room equalization and decorrelation in a "CAN" is a very difficult stretch because how can it be good for all situations.

IMHO
I think that it would be more beneficial if we could buy as a seperate after the DD or DTS decoding is complete a THX processor that could be switched on/off at will. This could indeed keep the price of receivers in line with consumer needs and an add on if the consumer so chooses.

I also don't put much merit on the THX standards ensuring high quality equipment. All equipment is prone to quality control problems from the component manufacturers through assembly. Just because a design can meet the THX Standards does not imply that the equipment manufacturer has met all the ISO standards. I have read on other posts that high end audio gear is taken out of the box set up and then it does not work. Now that is enough to piss of Mother Teresa!

Just a quick rant while trying to avoid work while in the office. ;)

HBomb

[TroyD]

That's my point exactly HBomb. It would seem to me that internal THX processing, for better or worse only give you what the THX folks want you to hear. I'm not saying it's bad or good, but in the end, it's more artificial manipulation of the material.

As far as outboard EQ issues, I'm not getting what makes THX gear any better or worse than non THX.

BDT

[brettw22]

I'm looking to get a new receiver and have a question for you Troy and Russ.....

With the Re-EQ on the Onkyo and the Dynamic Correction(or whatever) on the Denon......are those are modes that you can turn off, kind of like HALL, ARENA, LIVE, etc modes or are they always running in whatever mode you put the receiver in, be it dts, dd, or whatever other options there are........

[goingganzo]

what i get is that the center in the theaters are behind the screen so they lose a bit if the high end so they bost the high in the center so your center is not behind a screen so it is extra bright this is what i get from this.

the olny thing i would buy with thx is a pre amp that is the olny thing that you get sothing for the thx cert amps you get nothing and same thing with speakers

i also think that the thx comp speakers is stupid

[TroyD]

Brett,

With the Denon, it's a feature that you can turn on and off in the setup menu. I'm sure it's the same with the Onk.

BDT

[RuSsMaN]

Yeah, it can be turned on/off with my Onkyo, seperate of the DSP's available.

Cheers,
Russ

[rlw]

The usual disclaimers apply: I'm an a$$hole, etc. I'm certainly not a professionally certified installer, thank god.

THX RE-EQ: it's actually not designed for all soundtracks - it's designed for those soundtracks which were recorded and processed to THX standards.

Remember how I babble on about the room contributing so much to the sound? Well, that's kinda the point of the THX RE-EQ: a movie theater - especially a movie theater built to THX standards - has a certain frequency response. That frequency response tends to be rather dead: heavily ulpholstered chairs; thick carpets; heavy drapes and valances; however many people wearing whatever clothes: these all contribute to the overall "dead" nature of a movie theater. ALL THX soundtracks have the treble registers "shelved" a bit higher to compensate for this; probably, most soundtrack engineers push up the treble on non-THX soundtracks as well.

Move to the typical home theater: room is considerably more lively; smaller; you sit closer to the speakers, etc. THX RE-EQ shelves down the highs by an amount corresponding to the "upshelf" in the recording/production process.

Why is using a THX certified processor good for this? Well, you know that you're getting the correct amount of shelving - the idea behind THX is to control the entire chain. Since THX is involved in the production, then it would seem to have an advantage over any RE-EQ from Onkyo, Yammie, etc.

Why is using an outboard graphic/parametric [but analog] eq not as good? Well, in the analog domain, any change in frequency response causes a change in the phase of the waveform: subtle timing queues get lost. That's why some speaker manufacturers [Thiel, Vandersteen, others] put so much emphasis on the phase coherence of their x-overs. That's why, if you're implementing a line-level x-over, it's easier to get better integration results using fourth-order x-overs: the phase of the signal is not changed.

In the digital domain, you don't worry about phase - there's other things to worry about, and which are tough to get right, but it's easy to do a phase-coherent tone control. There are some digital EQ's on the market, but tend to be rather pricy or have some serious performance compromises.

OK, so that's why THX re-eq makes sense to me.

Adaptive decorrelation: this is used in ProLogic soundtracks. Basically, the rear channels receive the SAME mono signal. If you've ever listened to mono, you know that you don't get a sense of soundstage space/depth. So, you have to matrix the mono signal, with a twist, to get depth: you have to change the phase of each channel on the fly. ProLogic does this, but THX, once again, does a better job b/c of involvement in the recording/production side.

THX speakers: the THX spec covers a few things, including timbre matching, dynamic range, dispersion, and speaker configuration. These are all just specs that the manufacturers must meet, no technology.

Why are these specs good: well, again, it comes down to control of the entire chain. Buy THX speakers [all of 'em, not just the fronts], and you're guaranteed to get timbre matched tone, controlled dispersion, and, combined with a THX processor, speakers which are designed to function optimally with the 80Hz x-over point for the sub. This might not be the best for music - for example, you might believe that full-range fronts are important, or that full range on all channels is important - but it's good for movies.

What's really bad about THX for multi-channel music are the rear channels: THX requires "DIFFUSE SOUND" [dipoles/bipoles, etc] on the rear channels, which is in direct conflict with what mulit-channel music [SACD, DVD-A, etc] is produced to work with: 5 identical speakers.

THX wire: if you've ever seen a complicated home theater installed by your average installer, you'll begin to appreciate that color-coded wires make a lot of sense. I have yet to meet a home theater installer who has heard of, let alone uses, the following:

3M Cable Labels

which kicks the color-coding scheme's ass, but takes some extra effort.

THX test tone level: really useful in that it speeds up the calibration process. Use a THX processor, a SoundControl Meter with a big readout accurate to .1dB, and you can quickly dial-in the sweep tone so that there is no variation across channels. Yes, you can achieve equally good results using non-THX test tones - but it takes quite a bit longer and uses more patience.

Complete control of the process, including installation, makes for a more consistent end product. Some of the THX specs relating to installation help remove the "chimp factor".

Take it for what it's worth. I'm going to go listen to some vinyl.

[TroyD]

rlw,

Thanks, again that was well written and VERY informative. Now I see a method to the madness and what everything does. I'm not saying that I'm a convert to THX but that sheds light on what THX has to offer and how it does it.

BDT (feeling a little dumber every time I read an rlw post)

[rlw]

Originally posted by TroyD
rlw,

Thanks, again that was well written and VERY informative. Now I see a method to the madness and what everything does. I'm not saying that I'm a convert to THX but that sheds light on what THX has to offer and how it does it.

BDT (feeling a little dumber every time I read an rlw post)

Thanks for the kind words, sir, and glad to help. You have nothing to feel dumb about: you have a great grasp of what's important in audio, and you ask all the right questions. Everything after that is just details.

[xfontanax]

I'm confused. If you have a DVD with a THX soundtrack, as a rule of thumb, should you enable of disable the THX processing?

[jcaut]

Now that, rlw, was the most informative post about THX processing that I've read on here-- Thanks.

It's becoming apparent to me that there are really two aspects to the "THX" label that merit discussion. On one hand there's the processing end that was discussed above. Whether or not you believe it's necessary or even beneficial, at least it can be discussed as a "useable feature" on a THX certified processor or receiver.

The other end is the so-called "performance standards" that gear must meet in order to receive the "THX" stamp. I think this is where most of the controversy originates. For instance: Is a THX certified power amp necessarily better than a comparably powerful, non-certified amp? What about speakers? Would a THX-certified multimedia/computer speaker system do a better job reproducing a movie soundtrack than my non-certified Polk RT home theater speakers? I think we all know the answers to those, and in those cases I think THX is just a label that probably ends up costing you money for no performance benefit.

Jason

[rlw]

Originally posted by xfontanax
I'm confused. If you have a DVD with a THX soundtrack, as a rule of thumb, should you enable of disable the THX processing?

The only rule of thumb that matters: what sounds best to your ears with your gear?

The THX folks will tell you that THX processing should be enabled for optimum playback of THX tracks.

[MxStYlEpOlKmAn]

rule of thumb - you can only beat ur wife with something no wider than your thumb.

[HBombToo]

Originally posted by MxStYlEpOlKmAn
rule of thumb - you can only beat ur wife with something no wider than your thumb.

No! No! No!... Young Man!

The rule of thumb is a Man should never even touch a Woman in Anger!

Now this is a Great Thread...Thanks RLW.

HBomb

[madmax]

The only thing I wonder about is if THX mastered discs are meant to be used by consumers in the home (they have a legal notice on every on saying that is the only way they can be used) then why is this processing not being run on the content before it is encoded on the disc? Huh?
madmax

[madmax]

OK,OK, so they are not THX mastered, they are DTS or Dolby mastered. But still, shouldn't they be enhanced before they are encoded on the disc? I'm not sure I want anyone futzing with the material anyway but it just seems they should try to pursuade the people mastering the discs to correct any problems.

I'm sure that fixing one master costs WAY less than providing everyone in the world with additional equipment.

I think they just want the added cash.
madmax

[rahvin]

i have the onkyo 797 with rm6700s and a velodyne 10. i have noticed that on thx enable dvds everything seems more descrete. there is less ambient sound. i flip it back and forth between thx and non all the time as usually i can't decide which i like better. thx seems more descrete but it is not as imersive an experiance--which is what i am shooting for. it also requires me to turn up the amplifier much louder to hear the dialouge.