Q: Stargate: UE, dts LFE vs. DD LFE
 

I've watched the entire movie and noticed something odd. There have always been differences in the LFE mix on DVDs that have both DD and dts (ala Jurassic Park triple pack). I have noticed the following in the Director's Cut using my trusty Ratshack analog SPL meter:

Time 33:41, Flare lites up, dts LFE is 10dB lower than DD LFE.

Time 1:05:08, Alien ship landing, dts LFE is 2dB lower than DD LFE.

No dynamic compression is active. Dialog is normalized between dts and DD with no need for compensation.

Why the hell there is such a huge difference? If I try to boost dts LFE, I risk having overblown bass in lots of scenes, while other scenes need as much as 10dB boost to sound similar to DD levels! What gives?

I have Philips DVD-825, and Pioneer VSX-D608 receiver connected optically. Anyone with similar observations? Thanks.

Although there is no DTS version of the movie, I've noticed that the DD5.1 track on Deep Impact has some very impressive LFE engagement. The original Resident Evil release in DD5.1 is another prime example. It sounds fantastic overall, and the LFE power on it is frighteningly good. In fact, I refuse to buy the Superbit DTS version of it simply because the DD5.1 is so good. I've also heard some other people commenting that LFE usage is often better in DD5.1 tracks rather than DTS.

I generally prefer DTS, however, because they tend to be better overall. DD5.1 tracks can be anywhere from amazing to absolute crap, whereas DTS tracks are almost always very good. That's my experience with them, anyway :)

It should be pointed out the Superbits edition of Resident Evil (and every other Superbits disc with 5.1 audio) has both a DD 5.1 and a DTS 5.1 track. Superbits does not mean just DTS audio.

I know that :) I'm just pointing out that the original edition's sound is of such high quality that I hardly see how DTS could improve on it. When done properly, DD5.1 can easily rival most DTS tracks. Unfortunately, most DD5.1 tracks aren't done as well as most DTS tracks.

^BUMP

Can some1 please take measurements at the times I pointed out to see if I have an "equipment" problem or not? It is so simple to switch between dts and DD on this DVD, just hit the audio button on the DVD remote. No need to go back to the menues. Thanks.

Of course I agree. I don't think the half bit rate DTS tracks are any reason to buy a Superbits disc in any case. Superbits is primarily about better image quality, and in most cases even that requires a larger display (say, over 40") to make much of a difference besides.

VelociRacer:

I'll see if I can take some measurements for you, but it will be either late tonight (sunday) or tomorrow before I can find time.

In many cases, the DTS on the Superbits is better than the DD. Just take The Patriot, the 5th Element, or Air Force One for example. This is not always the case, though. DTS is not always better. On the Rock CC, the DD is clearly the winner. I have not heard the DTS on Resident Evil but I do agree that the DD is so good that I would be suprised if the DTS yielded a significant improvement.

VelociRacer:

I checked the two time references you noted in the Director's Edition disc of the Stargate UE and I do measure some variation in the low frequency energy between the DD and DTS tracks, though not quite as much as you do on one of them.

I measure a 5-6 dB difference here...

I get a 3-4 dB variation here.

This is not inconsistent with what I have measured on a number of other soundtracks where the same master was used for both DD and DTS tracks with the DTS track not having any compensatory eq. It has been documented by others that DTS (encoder) does not reproduce flat response in the LFE. In Dolby's now infamous white paper on DTS using the CAE-4 encoder, Dolby measured -1dB @ 50hz, -3dB @ 90hz, -6dB @ 120hz in the LFE channel. These measurements have been verified by others using PC-based spectrum analysis on a number of DVDs.

Depending on what frequencies were used in the LFE channel in the specific passages referenced above, these measurements appear to be accurate and except for the 10dB variation you note, consistent with normal DTS encoding. It is possible the greater difference you noted at the 33:41 mark could be related to room mode issues. I will mention here that my sub has been eq'd in my room for relatively flat response so it is quite possible, even likely, we will not get the exact same measurements.

The other possibility is that whoever mastered the audio simply screwed up ;).

Thanks for your help Robert. I shudder to think we all dump our money on dts titles only to find out it was all to waste and we have to revert to DD anyways for the all-too-impressive LFE content of these action-packed movies (StarGate, Jurassic Park, U-571, Titan AE, SPR, Thin Red Line, Apollo 13, etc.).

Anyways, there goes my blind trust in the dts sound engineers :( I wish someone would tabulate the dts titles and list technical flaws in sound compared to the accompanying DD track.