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Thread: DTS vs. Dolby Digital. The subwoofer. |
    
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| Posted on Sunday, July 06, 2003 - 01:40 pm: |
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DTS vs. Dolby Digital
Over the last few months I have expanded my stereo system to get 5.1, and it is a great pleasure. Watching movies is better for the whole family, and more of a shared experience, an unexpected benefit. The final link in place was a sub. I don't think the brand matters here.
DTS is really great. I connect the sub to the line-level 0.1 receiver output. With the sub "level" control set at 12 o'clock, the sub sounds exactly like a natural and balanced long downward extension of the whole system, in the whole room. Low frequency extension shakes and surprises you. It is part of the experience.
Dolby Digital, with same DVD, set-up and settings everywhere, is really bad. A lot of detail is missing from all 5 channels, especially the surrounds. But the big issue is the sub. Dolby Digital gives continuous high levels of pointless bass. It is tiring, and removes the drama from explosions and all that, because you have been blasted with bass all the way through, anyway. Anything with a bass guitar is a complete pain, like "megabass" stuff on a cheap Walkman.
Is it the sub? No, it is the same sub. Same connection. Same settings.
Is it the receiver? Well, I can turn down the LFE channel 6 dB and Dolby Digital is still far too loud out of the sub. And the peaks still come as no surprise. For example there is a great thunderstorm in The Bourne Identity (good movie). It is startling in DTS, just more noise in Dolby Digital.
Is it the processor in the receiver? If I turn off the sub and direct the LFE channel to the main speakers the problem is not there, or not as much. Maybe the processor in the receiver has got it all wrong? But it is an OK make, and has the Dolby double-D badge.
Is it the source? All DVDs with DD and DTS give pretty much the same result, so this seems unlikely. And not all recording engineers are addicted to banging their heads against walls. If they were, why would they do it only in DD? Has Dolby advised recorders to put 10 dB extra sound pressure level in LFE for some reason? I have one 5.0 DVD-audio disk. DTS does what it says on the tin. DD gives a 0.1 output anyway. And it is far too loud. Does this mean the processor is at fault?
I have read up what Dolby and DTS each have to say about their two competing systems. I greatly prefer DTS sound. Dolby rubbishes DTS but to me Dolby's arguments are as bad as their sound. At least on my system....
This DTS link is interesting and makes a lot of sense:-
From Dolby about LFE and subs:-
One thing it says there is "The LFE channel carries additional bass information to supplement the bass information in the main channels. The signal in the LFE channel is calibrated during soundtrack production to be able to contribute 10 dB higher SPL than the same bass signal from any one of the screen (front) channels." Does anyone think this means that the same bass should should be increased 10 dB (more than eight times louder) through the LFE channel than any single channel? That is absurd and cannot be what they mean. But then "supplement" is the wrong word. And they don't mean "signal in the main channel" they mean "bandwidth" or "capacity". Maybe someone takes them at their word, and puts + 10 dB on the LFE signal just to blast the listener? Some of my DVDs sound just like this. By the way, "High Level Description" it is not. "Confused ramble" would be more like it.
Where I live we get mostly specific region 2 DVDs, and DTS is usually sacrificed for dubbed DD 5.1 channels. You have to look hard to find a DTS disk for rent or sale.
My main question. Which component is at fault? I only have one system with one of each component, so I can't experiment. I can't find anything about this anywhere, so maybe it's my system, not the recordings.
Does anyone else experience a massive difference in sub output between DTS and Dolby Digital?
John Allen This message is posted on both Home Audio, Speakers and Home Theater. |
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timn8ter |
| Posted on Sunday, July 06, 2003 - 02:08 pm: |
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I like DTS better also. The sound coming from each channel appears more discrete. The bass seems better also, not exaggerated as it is sometimes in DD. I haven't experienced the level of pointless bass you're describing. Have you ever run test tones through your system? The easiest and most inexpensive method is to pick up a SPL meter from Radio Shack. An analog meter will work fine. Personally I prefer the digital one, only because it's easier to read. Test tones can be had at no cost, downloaded from the Internet. Play the test tones and record the results, taking readings at all the various listening positions. All rooms will have null points and reflections. I enjoyed reading F.E. Toole's paper titled "Getting the Bass Right" which can be found on Harman's web site. Placement of the sub is a big factor but it's almost a neccessity to use a good parametric equalizer to get it right. If you'd like more info please let me know. |
Derek |
| Posted on Sunday, July 06, 2003 - 06:13 pm: |
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John, I have heard completely different bass levels between DD and DTS. I simply chalked it up to the mix, get on my knees and turned my sub down.
I keep hearing that DTS sounds better because they use less compression but I can't realy prove it because I have found that the mixes are different. Objective reviews in mags like Sound and Vision weren't definative either.
Timn8ter, what tones are you refering to? Anything John plays will only be good for that source unless he can encode a DTS steam. I think John need a DTS test disk. I have AVIA and it does not have it. Video Essentials doesn't have DTS either. I haven't tried these but they say they do.
http://avconvert.com/quad/test.html
http://www.jvc-victor.co.jp/english/media/testm/dvd-pro.html
http://www.burosch.de/deutsch/Professional-DVD-English.php3
http://www.michaeldvd.com.au/Reviews/Reviews.asp?ReviewID=1124
P.S. If you buy an SPL meter, use laptop and this (http://audio.rightmark.org/) software to test your system.
Hope this helps. |
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| Posted on Monday, July 07, 2003 - 06:16 pm: |
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Tim and Derek,
Many thanks. I live thousands of miles from a Radio Shack but I will investigate local SPL meters. All my subjective tests confirm the tiring bass on DD compared with DTS. I do like low bass, just not all the time.
Yes, I would like to get hold of a DVD test disk. The JVC link looks like the spec of a good one. I have a Denon stereo test disk and I think it is only a matter of time before a home theater test disk is available retail.
I have just burned an ordinary CD with various 5.1 mutichannel audio tracks from a Swedish radio web site. Some have the same content in DTS and in DD so you can compare and there is no contest. Quite a lot of the demos are in English. They claim to broadcast in mutichannel, too. How do they do that? Here is the link. The car chase and Banff demo are good. The Firebird in DTS and DD is cool a perfect example of DD's over-the-top LFE channel.
http://www.sr.se/multikanal/english/e_index.stm |
timn8ter |
| Posted on Monday, July 07, 2003 - 07:05 pm: |
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Whoa, what happened to my post. I was attempting to answer Derek's question. Based on the lack of evidence for a huge sound difference between DD and DTS it seems logical to investigate the subwoofer itself. Not that there's anything wrong with the sub but low frequencies are impacted in a huge way by the room. Even if this isn't the problem it's still good practice to take the measurements and work with placement, gain and EQ of subs. |
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| Posted on Tuesday, July 08, 2003 - 07:37 am: |
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I have had posts go wrong too.
My Denon stereo test CD has frequency sweeps and test tones with equal SPL at different frequencies. If I had something like that for DTS vs DVD it would help. The Swedish Radio files are good, this is the link again: Multichannel SR 5.1. The multichannel check (bottom of the web page) gives you clear speech with "My voice is heard coming from the __ channel" (but in Swedish, a lot of the rest is in English). Speech is always a good test of sound reproduction because our brains are tuned into it. But voice never needs an LFE channel. Even the deepest male voice has no part going below about 65 Hz, and bookshelf speakers will do that.
What I find after more listening is that the exaggerated bass in DD is there with the receiver set to give all 5 channels full-range and with the sub on. The voice in the channel identification and level test sounds like an monster from a sci-fi movie. The bass in those voice recordings is still a bit exaggerated in DTS.
With speakers set to small on the receiver and sub on, DD and DTS are both a bit boomy but about the same extent (the DTS is much clearer higher up though).
Sub off and low frequencies sent to the L and R main channels is by far the best choice for voice. And then you hear the extra DTS clarity, no question.
So it would look like my sub level is set too high. But on music and special effects the DTS with speakers set large is excellent, the DD ridiculous and so bass heavy. I now watch DD movies with a 6dB cut on DD compared to DTS.
If the exaggerated bass is a result of bad sub placement, Tim, shouldn't be the same with DD and DTS?
As regards Derek's comment "I keep hearing that DTS sounds better because they use less compression but I can't realy prove it". Well I can hear it. Consistently. On everything. It is striking improvement in clarity on every channel. From spoken voice to big orchestra or rock. Compare Swedish Radio's DTS and DD Stravinsky Firebird 1 clips - the first few seconds are enough to prove the point. For example also a nice little tambourine comes in at about 3 minutes on DTS. If you listen very hard on DD it sounds like someone's rustling aluminium foil somewhere. Quietly. You could write tons of examples on just those two clips.
As to why, well there is the superior sampling frequency and the method of coding, see Brief History and Technical Overview. Then again it is clear if you download the Swedish Radio files that the DTS .wav files are twice the size of the DD files.
I conclude that if you like good sound reproduction you will choose DTS every time. Dolby's business is compression, always has been since tape cassettes. I suppose it is a marketing decision. Leave off one DTS track and you can get the whole movie in two more languages in DD, or with a whole load of add-ons.
Tim, I will try to get an SPL meter, check it out, and report back. The sub is near a corner (about 9" clearance both walls) at the moment and I will move it round a bit but there are family and space considerations in which I am sure I am not alone.
But original question remains. Does anyone else hear, or measure, this huge difference in bass between the DTS and DD?
Thanks for your comments, guys, I really appreciate that. No-one has yet responded to my same post under Home Theater. I guess this is an audio issue. But it's funny how much good sound makes or breaks the movie, even if you're not into technicalities. Someone should tell 'em!
All the best. |
timn8ter |
| Posted on Tuesday, July 08, 2003 - 09:17 am: |
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If you like you could read these threads. http://www.hometheaterforum.com/htforum/showthread.php?s=&threadid=147072&highlight=dts
http://www.hometheaterforum.com/htforum/showthread.php?s=&threadid=147355&highlight=dts
http://www.hometheaterforum.com/htforum/showthread.php?s=&threadid=148017&highlight=dts |
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| Posted on Tuesday, July 08, 2003 - 11:11 am: |
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Thanks. I am new to all this and see from those links it is a big issue. Nothing there about bass or LFE differences, though, my original question. I could easily tell DD 5.1 from DTS on any of the disks I have, in a blind test, and with the sub switched off. My player and receiver have 96 kHz/24 bit DACs, and this is given next to DTS on some DVD-audio disks and on the Swedish Radio files. What is meant on that forum by "full bitrate DTS"?
I remember the 44 kHz sampling frequency limit of CDs being an issue with the analogue people (I am still one at heart). But I have eventually come round to thinking there isn't much missing from good CDs. So I decided against getting a SACD player. DVD-audio in DTS is so good it makes me wonder if this was right. I do think Sony and Philips must take us all for fools in pushing SACD; they agreed in 1983 that CDs gave "perfect sound that lasts forever" and are now flogging SACDs made from 1960s analogue master tapes. In the end, sound is analogue, and even the consumer electronics giants must know that. Speakers are certainly analogue devices.
Must curb tendency to rant.
Thanks again. |
Derek |
| Posted on Tuesday, July 08, 2003 - 12:25 pm: |
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John, I created the CD and ran some tests. In the end I found that the subwoofer-out of my receiver is 4db lower on the DTS track compared to the DD track. I had to normalize the measuremnts the results because the DTS track was 2 db quieter (a 6db total differnce for the sub).
The spectrum analysis of the tracks are the same. I looked at the left front and the center channels. With the sub disconnected (not turned off by the receiver) and correcting for level, they look and sound the same. I conclude from these measurments that the difference aside from absolute level is the difference in sub level. It's probably a difference in the spec for DTS and DD. You would think that the mixing engineers would compensate for this but it appears they leave the DD at full output to make the tracks sound more thrilling... Maybe this doesn't work for music.
I used and old Philips 5 MHz oscilloscope, SpectralRTA sofware on an IBM T20 Laptop, An Asus A7N8X motherboard (that encodes DD in real-time), a Samsung 52,24,52,16 CD-R DVD Combo drive, the Denon 1801 receiver, a Philips 724S DVD player and a 15 year old Maganvox 460 CD player with digital out. The Denon did all of the decoding. The computer and the Magnavox produced garbage out of thier analog AND digital outputs.
Hope this helps. |
timn8ter |
| Posted on Tuesday, July 08, 2003 - 12:39 pm: |
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Bit rate refers to the data transfer rate and is usually measured in kilobits (Kb). Full bit rate is the highest data transfer rate that can be handled by whatever technology you're running on which can also translate into the least amount of compression that can be used. In case you haven't had enough to read here's another link.
http://www.dvdangle.com/articles/dvd_101/102501.html
DD uses a higher compression rate than DTS which is generally accepted as being the reason for the better sound quality. As you've been discovering it's a little more involved than that. |
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| Posted on Tuesday, July 08, 2003 - 01:36 pm: |
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Derek,
Well thank you for that. I would guess that the 6 total dB difference for the sub is about what I hear, too, on my system. But it is not just those Swedish Radio clips, it is everything. Maybe I haven't made enough DD/DTS comparisons yet, but I do not yet know of an exception to this thumping bass on DD when the controls are just right for DTS. That sounds like fun set of measurements. The DTS web site flags the Swedish Radio clips, so I guess there aren't so many around.
Tim,
Thank you, too. I see now. It is kb per second, kbps. Full rate DD is 448 kbps. Half rate DTS is 754 kbps. I do not know which I have been listening to.
I am learning some things here. |
Derek |
| Posted on Tuesday, July 08, 2003 - 01:50 pm: |
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Yeah, I would imagine DTS would sound better. They seem to be a little more concerned with audio quality and they do use a higher bit rate. This high rate and additional licence fee explains why DVD producers aren't using it as much. It's all about sales. I will have to get my hands on DTS test DVD with calibrated levels and do some tests though.
Now I have a new project. Thanks |
matt McCann |
| Posted on Sunday, August 03, 2003 - 12:22 am: |
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I have heard a similar bass difference on both mine and my friends systems. Try Gladiator which has both DD and DTS. The DTS has much less bass coming from the sub and much clearer audio overall.. Also try Terminator 2 which also features both audio options. DTS, in my opinion, based soley off what i can hear sounds better every time over Dolby Digital. |
Ryan Johnston |
| Posted on Tuesday, August 05, 2003 - 11:47 pm: |
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I have tested both sounds (DTS and DD) and i find that DTS blows DD out of the water. The sound is just way more involved in the movies i watch! I can make out nosies i have never heard before with DTS, then that i would with Dolby |
John Allen |
| Posted on Wednesday, August 06, 2003 - 02:27 am: |
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Now I find the bass-heavy DD effect goes away when the sub is connected to the speaker output. But DTS still scores higher for sound quality in every way. I wonder if DD is doubling the bass to the dedicated ".1" LFE channel by giving it the low frequencies from the main channels, too, in order to try to compensate for small main speakers? Or just to blow the socks off customers in brief showroom demos?
Back to using the "Sub out" line output, I get the impression DTS mixing assumes a decent audio system; with DD the effect is like "mega-bass" on a Walkman. Argh. Mega-bass effects confuse bass volume with bass extension. Is this DD's problem? If you have a sub at all, you don't need to color the sound like that. The effect is not in-yer-face, its banging-yer-head. Against a hard wall.
Thanks, Matt and Ryan. I agree Gladiator and Terminator 2 demonstrate the superiority of DTS. We recently got The Fellowship of the Ring extended version. The DTS sound is miles better than the DD on the same DVD, or on the standard "theatrical" release (DD only, here). Apart from the DTS, the extended version also retains lots of great scenes (informed family members say the extended T2 retains scenes that made great cuts...). Will wait for the extended Two Towers. I have not heard a single example of a movie or DVD-audio where DD comes even close to DTS for making you feel you are there, in the middle of it all. |
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| Posted on Thursday, August 21, 2003 - 03:23 am: |
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Guys, i just want to thank you for the information you have collected here. It was very usefull and entertaining. Things like this make the net valuable cuz you can check out anybodys experience and learn from it. I would like to make a contribution to this discussion but i did not know a thing about this until i checked out this page, all this due to the doubt i got from reading my dvd specs and starting to ask myself wich could be the difference between dts and dolby.Thanks from Argentina.(excuse my crapy english) |
John Allen |
| Posted on Thursday, August 21, 2003 - 11:53 am: |
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Juan,
Thanks!
If anyone likes their small number of "classical music" releases, there are some great DVD-audios on the budget label Naxos. They have Dolby Digital and DTS, and you can switch while paying. Just listen. There is no contest. |
John Allen |
| Posted on Thursday, August 21, 2003 - 03:14 pm: |
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Sorry, "while playing". |
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