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Author Topic: DTS - SRD Levels and quality considerations Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 05-04-2005 09:18 AM                        Hi everyone It is an old question that I've read thousands of time here and in other places: Is DTS better than SRD? I'm not here to open another thread on this, of course. Today I spent a morning making some interesting tests on my biggest screen, equipped with CP650, DCM monitor, DCA amps, Martin Audio 6B screen speakers, 6 Martin audio Subs and 16 Martin Audio horned surrounds. Plus a DTS6D of course. I took a "Broadway 2000" THX trailer, I made a loop and, with the help of some spare rollers, I made this loop running continuously on the projector. Then I made these tests, read up to the end, there are something that I didn't expect. The DTS processor is set up at 300mV RMS all channels. I usually go to the auditorium and have the THX trailer run several time in SRD and then in DTS so that I can compare the sound quality and the overall levels. Please note that I made these tests one channel a time: Surround, THEN stage, and THEN Subwoofers. Not all toghether. In general the more quality of the sound of DTS was always present, I noted VERY VERY well in surrounds, where SRD compression was very high and the differences in quality VERY HIGH. I could say if was SRD or DTS in any moment, the DTS' high frequency quality was light years far from SRD ones. Surround level was the same between the formats. On stage channels the differences are less noticeable, perhaps because Martins are very good speakers but they're not as well as JBL or EV on High Frequencies over 8000Hz or because the front sound of the Broadway 2000 is not so complex. However, there are sounds you can ear in DTS that cannot be heard in SRD! With Subwoofers, I expected some differences since the way that SRD and DTS handle the signal is very different (DTS filters out Subwoofer channel from surrounds). Do you know "Broadway 2000"? The Sub track starts with "high" frequencies (for a sub!) like 100/150Hz that blow your head and then run lower and lower until the seat start shaking! Well, of course the first part of the track is not present on DTS because the sub is cut off at 80Hz. Seems that SRD SW track is there only when designed while DTS adds some "garbage" coming from Surrounds, but nothing important. The overall level and depth seems the same between the two tracks but, again, what you hear was not the same. Then, I take my notebook, equipped with a very flat M-Audio soundcard. I connected the soundcard's inputs on Dolby's Test point and I recorded the SW outputs of SRD and then DTS formats. See the graph, made at 1/6 octave and with "Peak Hold" enable. This is the Center Channel, SRD first and then DTS This is the Subwoofer channel, SRD first and then DTS Subwoofer channels made me thinking... In SRD from 80Hz up to 150Hz there are the "head shake" that is missing in DTS but I don't think that it is an issue... Look carefully at the very low end. Under 35Hz or so, DTS track is not at the same level of the SRD one! Ok, not many sound systems are capable of frequencies under 25/30Hz but... I made the same test bypassing the cables on the rack, connecting the probes under the first "sound" cable connected at the DTS (next time I'll connect the probes directly after the plug behind the unit!) and the result was the same. Should I think that DTS subwoofer soundtrack is not as deep as SRD? Ok, it depends of the recording... What do you think about that? I'll wait for your opinions! Bye Antonio  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 05-04-2005 10:00 AM                    It amazes my how technical some people need to get. Will the numbers determine what sound format you enjoy a movie in? Will people look at the numbers and say "well, the numbers say this sounds better, so I better enjoy it"? This is not a flame of any sort, but I just dont understand why things have to be over analyzed so much. If its a passion to check the numbers, fine, but for me, I just walking and listen to the movie. Based on my years of movie watching, I personally have determined that DTS has better sound...to me. I dont need scopes, computers and analyzed numbers to tell me that.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 05-04-2005 10:15 AM                     Antonio, my recommendation to you is to stop concerning yourself so much over it. Plus, use an actual reel from a movie, not a sound demo. It is not uncommon for different versions of a sound demo logo trailer to have noticeably different mixes. The biggest offender of this to date is the THX Broadway as you compare it to the 3 different digital formats. I do personally find that SRD packs more of a punch than DTS and I prefer the full range in the surrounds that DTS does not provide. I also find DTS can sound a tad harsh with some speakers (EV is a good example). However these are minor points that would in no way stop me from running or enjoying a movie in DTS if the auditorium was so equipped. Bottom line: get over it.  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 05-04-2005 10:28 AM                        Brad I accept your raccomandations, it's just curiosity, don't worry that when I go watching a movie I just see and listen, and I do not think at other. But, I'll never stop thinkering around equipment, curiosity is an human feature!! Bye A  |  IP: Logged Steve Scott Phenomenal Film Handler Posts: 1300 From: Minneapolis, MN Registered: Sep 2000 posted 05-04-2005 10:54 AM                     Antonio, bravo for bringing it up with such technical specifics! Though the arguement will undoubtedly live on, its good to see someone go to such lengths to try and answer/pose the question  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 05-04-2005 11:56 AM                     Is DTS Better? YES Why? Because the Timecode keeps reading all the time unlike SRD which gives a fault error of 99!!! after several years of film playback And the question still leaves on D  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 05-04-2005 02:49 PM                     Uness you have the very best of B chain equipment anbd a very good NC level and decay time in the room its hard to tell the difference. DTS does use very little data compression as compared to SRD and that can be an advantage. I also prefer DYTS surround arrangment in where the vlf comes fomr the xubwoofer and not the surrounds. Distortion levels in the LF realm and kept alot lower that way. DTS also has lossless(compression free)systems available based on the XD-10 and its doubtful that Dolby could ever pull that off as there isn't enough storage room for all the dats on the film, although it could be stored on a HD. I like both systems and the reliability of each seems to depend more on where you are and what grade prints you are sent. I can live with either one but since I much prefer the Panastereo CSP-1200SRD processor over anythng else available I have been installing more XD-10's lately with them. OUt of the box the XD-10 is capable of 8 channels and can run 24 bit 96khz digital... another tow important advantages that can be utilized some time in the near future. Mark  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 05-04-2005 03:38 PM                        Mark I'm a great fan of DTS, my analisys was not to declare a winner in the eternal battle between SRD and DTS... Mine are just facts: is as Brad says and it is just a flaw in the final encoding or, really, DTS subwoofer track isn't able to go down up to 20Hz? It's just curiosity, of course, but I like to have the best from my sound systems and I'd like to know the "secrets" of both systems. No particular motivation, just curiosity. I do it for fun and personal satisfaction. About personal taste and feelings, I was surprised by the surrounds tests: I could say in a moment if the format used was SRD or DTS... No doubt. And it was not a level issue (where one format has higher levels and sounds "better"...) Bye A  |  IP: Logged Bruce Hansen Jedi Master Film Handler Posts: 847 From: Stone Mountain, GA, USA Registered: Dec 1999 posted 05-04-2005 04:39 PM                     Interesting tests, Antonio. Don't let the "I don't ask questions, because I may not like the answer" people get you down. The way to find answers is to ask questions. If you like tinkering, as I do, than tinker. The way to find the truth, is to search for it, and not to just blindly believe everything your told.  |  IP: Logged Lyle Romer Phenomenal Film Handler Posts: 1400 From: Davie, FL, USA Registered: May 2002 posted 05-04-2005 04:53 PM                     I see one fatal flaw in this test method. Since the AC-3 CODEC utilizes psychoacoustic masking as part of the compression, you cannot do a channel by channel comparison. The Dolby Digital track will not contain all of the information by design. The whole theory behind the CODEC is that certain information can be left out (or not coded as detailed) in one channel because it is masked by another sound from another channel (it's not as simple as that and yes, I've actually read the technical paper on AC-3). The only way to evaluate the two systems is an A/B listening test with material recorded off the same master. You'd also need different types of material because one system may sound better with one type of material where the other may sound better with another.  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 05-04-2005 05:20 PM                    I dont think its a matter of "I don't ask questions, because I may not like the answer", its simply that most people can go into an auditorium and know what sound they feel is best without test equiptment. I let my ear be the judge and not test results.  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 05-04-2005 06:30 PM                     I did a seminar a few years ago with 200 projectionists and techs outside of the USA where one of my guest teaching techs was pushing test equipment for basic evaluation. The proposed hardware was equal to a month or more of their salaries My turn I pointed out they have some very good test instruments....their ears and eyes. Systematic checkout ( blown drivers, rattling surrounds, general channel balance, light illumination on screen, etc ) using their "attached" instruments has greatly improved the theatre circuit and their field techs are doing more useful work.  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 05-04-2005 06:54 PM                    I agree with that. All the test equiptment in the world can say something sounds GREAT, but if the customers ears dont like it, then no charts or graphs in the world will convince them.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 05-04-2005 11:23 PM                     quote: Demetris Thoupis Because the Timecode keeps reading all the time unlike SRD which gives a fault error of 99!!! after several years of film playback I don't know what's going on in your booth, but I ship all of my prints out at the end of the run tracking typically between 0-2 at the highest...essentially about 1 point lower than whey they arrived brand new.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 05-04-2005 11:28 PM                     I question getting a second run print with a lower score less than a new print as for comparisons the clossest match on playback to the mag or D1 master is DTS in blind tests  |  IP: Logged

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