THX Films?

[Scotty Boy]

Hey folks.

Quick Q, if you could point me in the direction of an answer, or help me out, that'd be ace.

Recently upgraded my system with a THX amp and THX setup. So I was wondering, what films are about at the moment that support THX? I've just bought Finding Nemo and had no idea it had THX, how ace is that!

Cheers

Scott

[CarlB]

Films such as Findin Nemo don't 'have' THX, they are mastered in accordance with the THX programme. THX is not a sound format, but a set of guidelines for playback criteria to closely mimic a cinema or theatre.

Films with the THX logo will (and this is open for dispute in many cases) have assured quality in the picture and audio stakes by passing THXs 'rigorous' quality assurance programme during the mastering process. There are many bad THX certified discs, and there are many great THX certified discs, so I don't think it actually holds much weight these days.

I too have a THX amp and speakers, and the THX post processing can safely be applied to the majority of Dolby Digital soundtracks, with an aim to improving dialogue intelligibility and overall diffusion in the rear soundstage. The important point to look out for is remastered discs, such as many New Line discs from the Mi Casa facility, where the soundtrack has been re-equalised for home use. The application of THX and it's re-Eq feature (softens the treble on the front channels to counter the normally bright cinema soundtrack) on these discs will result in a dulled front soundfield. These discs should be played in vanilla Doly Digital.

I generally use THX Ultra2 Cinema for almost all Dolby Digital discs (except as above), but never use THX for dts as I am unsure if the re-Eq is required on dts discs.

[Phil Hinton]

Scott
THX is not a sound format, but a quality control system which is supposed to mean the print and sound have been mastered to the best quality possible. Any good DVD in our demo disc thread will sound great on your new system, enjoy!.

[Phil Hinton]

Carl got in there before me

[Scotty Boy]

Hang on, if it's not meant to be used, why the hell have they got a THX sound option on the amp? That seems kind of pointless.

I must say, I have sometimes put it on a THX, even though the film isn't THX certified, and Dolby Digital ES Enhanced sounds ****ing unreal, and knocks the pants off THX!

Cheers for the replies.

[Phil Hinton]

THX on your amp is a processing stage like a DSP programme. Not really much use for it nowadays as most DVD's are re-recorded for DVD release where in the past the soundtrack was the same level as the cinema which meant that the treble was pumped up as cinemas have perforated screens. But when played back on a HC system the treble could be over powering so THX adds a high frequency roll off to tame this. Like i said not really needed these days.

[Scotty Boy]

Oh ok, I think I get you.

You guys use way too many big words for a Home Cinema noob like me. but it's appreciated fellas.

I just thought it was silly and a bit stupid how some DVDs have a THX sound option, and yet, it's best not to use it. Even with a THX certified amp.

[figrin_dan]

Originally Posted by CarlB

overall diffusion in the rear soundstage.

Could you elaborate on that point please?
It isn't something I've heard mentioned before.
Cheers.

[MC Hammer]

I would add that don't fall in the trap of thinking that because it has a THX logo on it you will see a top PQ print.

Probably the worst PQ I've seen had a THX logo on it - Highlander R1.

I could quote other poor examples as I'm sure most others could as well !

[CarlB]

Could you elaborate on that point please?
It isn't something I've heard mentioned before.

The THX Ultra specification mandates the use of dipolar speakers mounted as the 'side rears' to create a diffuse and non-specific soundfield, as may be achieved with direct radiators. THX post processing also applies decorrelation to a mono (eg. Prologic) signal at the rear to further increase ambience. The THX idea is for a broad 'wash' of sound across the rear, supposedly to provide an enjoyable surround experience for more than one listener, ie. not just in the 'sweet spot'. Timbre matching is also used in THX post processing to reflect the difference in perceived sound from the rear as opposed to in front of us. The actual effects are closely guarded, but the desired result is to achieve a more seamless blend between front and rear speakers. Even if you have 5 of the same speakers, with no processing applied the rears will sound different as your ears are attuned to sounds in front of you. Timbre matching is designed to overcome these foibles.

All these techniques are designed to try and achieve greater cohesion throughout the soundstage, and to be honest I really like THX processing when applied to the vast majority of my Dolby Digital discs.

I actually use M&K tripoles as rear-side speakers, to give some diffusion but also achieve some directivity when required by spot effects. The THX spec has had trouble evolving since the days of Prologic to really account for discrete rear surround effects, and I think the use of dipoles in a current 5.1 system is pretty rare.