How bad is the audio mix on some DVDs?

[ChrisJam]

Hi,

Now that I've lived with my first 5.1 HT system for a while, I'm curious to know how movie audio tracks are mixed. Let me be more specific, because I've read the official versions about Dolby and TMX. That's the ideal, it seems, not the everyday practice.

If you've followed some of my posts, you know I've had lots of newbie audio questions. Since then I've tuned my system. It sounds good with 5-channel stereo (though if I do critical listening, I'll use 2-channel, with low tones sent to my sub, as it is with 5-channel). Some movies sound great, for example, "Speed" and "The Fifth Element." With these, I feel almost as if I'm in a theater. But I've found that some DVDs have bad audio. I'd like to know, please, if it's me, or if it's my set-up.

We watched three NOVA documentaries recently. Almost all the audio in them came from our center speaker. OK, I know that about 60% of a DVD's audio should come from that speaker. But even when some sound could be heard from my mains, the mains seemed muted, almost. The surrounds were almost nonexistent. (I'll remind you that CDs and some of the DVDs we've seen since getting 5.1 sound have wonderful presence over all the speakers. And we LOVE it!)

With one of the NOVA documentaries, an extra feature--the making of the doc--had better, more-balanced sound than the doc itself! The mains came into their own, though the surrounds were still weak. This makes me believe that the non-uniform sound is the fault of the DVD makers.

(BTW, this doc was made specially for an iMax theater, so I'd assume it would have had decent attention paid to the audio mix. But maybe the DVD audio mix is different from the theater versions??)

OK, maybe some documentaries don't have the greatest sound, and maybe it was our bad luck to pick three in a row that had inferior sound.

But last night we watched a DVD movie called "Simply Irresistible." It had the same faults as the NOVA docs--extra-strong center channel presence, weak mains, and almost nonexistent surrounds. I could decrease the sound from the center to compensate, but then when I played a DVD that had a great audio mix, I'd have to change the center dB level back to its normal place. This is a PITA with my amp, because I have to enter the test tone phase to change speaker levels. I think I'd rather live with a strong center presence for some things, and enjoy the convenience of not having to change things when I listen to 5-channel stereo or a well-mixed DVD.

If I'm missing something, please let me know. If this is something that comes with a 5.1 system--a weakness in audio-mixing with some DVD movies and documentaries, in other words--please let me know.

TIA,
Chris

 

[MDS]

Mixing and Mastering is going to vary from DVD to DVD, just as it does with music. The documentaries could well be mono (DD 1.0) which is why the center channel would be more pronounced. If you did the calibration of the receiver using the test tones then you've done what you can. You want to optimize for the good audio masters and just deal with the ones you don't think are done so well.

 

[Hi Ho]

My guess, in regards to the NOVA documenteries, is that they are simply mixed in stereo and your receiver was using ProLogic II to simulate surround sound. If there isn't much stereo seperation in the audio mix, this can cause most or all of the sound to come through the center and the other channels to sound weak. I can't say I've seen many, if any DVD's that had a truley "bad" sounding mix.

 

[ChrisJam]

Thanks, and follow-ups

We watched another movie tonight, "Dirty Rotten Scoundrels." It had a well-balanced mix between the center and the mains, but nothing from the surrounds.

It dawned on me as we watched, that the DVD probably wasn't mastered in 5.1 (I don't have the DVD case to look at). Does that sound right? If it's 2.1, would I get different sounds to the mains and the center like I got tonight? There was a different signal being sent to the center and the mains, not the same sound coming from all three. If a DVD is made in Dolby 2.1, what should I expect to hear from them with my 5.1 set-up?


MDS, thanks. Unless I come up a quick and easy way to change it, I'll live with the system being set for a well-mixed DVD. But Hi Ho might have a solution...

Hi Ho, you might be right about my digital effects being on for the documentaries. I think there's an easy way to turn the effects off, which'll give me whatever info is on the disc, right? I'll try that when I get a chance, maybe Sunday. Or is Pro Logic different from my amp's effects features?


A couple more questions, please: What's the advantage of my amp's digital sound field processor (DSP)? (My amp has the DSP, a Dolby Pro Logic decoder, a DTS/DTS ES decoder, a Dolby Matrix 6.1 decoder, and various combinations of these.) The DSP helped when I had a 2.0 set-up, and again when I got a sub to make 2.1. Now that I have 5.1 available to me, do you recommend that I keep the extra processing on or off? Is this something you might change from DVD to DVD?

 

[Jack Hammer]

One of the downfalls of a good setup is that the items that are poorly mixed become much more apparent. Conversely, the items that are well mixed sound much much better. I have heard a few dvd's that are poorly mixed and to be honest, they can just sound awful. a few have barely intelligable muted dialogue from the center channel, while the fronts and surrounds are overpowering you. Luckily, most movies have at least an "OK" mix.

It's also kind of tricky with the surrounds, I was convinced nothing was being sent to my surrounds on many occasions until I turned them off and listened again to the same passage. The sound field was much smaller and missing quite a bit. A well setup surround will add a lot of ambiance to the movie without being readily locatable. It will also produce specific easily located sounds. You might try to experiment with your surrounds both on and off to see how much of a difference it can make when you think nothing is there. In some cases you may be surprised.

my $0.02

Jack