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Speakers & Surround Sound A place to learn more about speakers, their functionality and how they can complement your entertainment experience. ![]() |
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#1 |
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Administrator
Join Date: Apr 2004
Location: Katy, Texas
Posts: 12,335
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Let’s Talk Surround
This is a page I added to the www.highdefinitionblog.com and thought it should be repeated here as well. A Bit of History With the movie industry continually trying to entice more people into the theaters, you would expect that surround sound would be another weapon in their arsenal and indeed it was. Surround sound in the movies started back in 1941 with the movie Fantasia put out by Walt Disney. Only two movie houses put in the equipment which cost in excess of $80,000, so it was some time before surround sound at the movies became mainstream. This early system required synchronizing two projectors; one for the film and the other for the sound. It was a four channel audio system. Later a magnetic media based surround system became popular for a while which could deliver up to 6 channels of audio. The problem with these early systems is they needed to be synchronized with the film projector and they were very troublesome to operate. They also applied magnetic strips to the film, but the cost of these films were about 10 times that of optical tracks. Additionally the optical tracks allowed for universality as the films could be played all over the world. The Big Breakthrough Then in 1966 Dolby Labs came out with a breakthrough in sound processing, the Dolby A-type noise reduction system. This would finally allow the optical audio on films to carry a stereo sound track. This was huge as it allowed movies to be shown on a single machine with a two channel (stereo) soundtrack. Soon thereafter the Dolby stereo system became a major breakthrough in movies with surround soundtracks. Using a process called Matrixing, Dolby encodes the stereo soundtracks with four channels of information. At first the Dolby Surround was three channels and did not have the center channel. Later the Dolby Pro-Logic include a fourth channel as shown in the following figure. ![]() As shown there are four discrete channels: 1. Left 2. Center 3. Right 4. Surround 5. Optional LFE channel ![]() One such problem that the four channel matrixed system had in addition to the positioning at the front of the movie was the fact that only a single surround channel could be encoded. Therefore it was best used for non-positional sounds like the noise of a crowd, thunder, ocean noise, etc. If, for example, the director wanted to have the sound of a train traverse from one side to the other at the rear of the theater, the Pro-Logic system could not accomplish that task. Another problem is that many home processors will pop and hiss due to a weird combination of frequencies that could confuse the decoder. This would result in a surround pop when an actor said a word that started with a hard P sound. The LFE channel was simply a crossover of the low frequencies that were in phase and sent to a separate subwoofer amplifier and speaker. The Digital Era Arrives. With the advancements made in the digital technologies, the first Dolby digital format (AC-1) arrived in 1984 followed by the AC-2 improvement. Dolby Digital (AC3) arrived in the cinema in 1992 which featured five channels plus a LFE channel: 1. Left 2. Center 3. Right 4. Left Surround 5. Right surround 6. LFE ![]() 6.1 and 7.1 Systems. The 6.1 system is a product of Digital Theater Systems, Inc. (DTS) who develops surround systems the same as Dolby. With a DTS 6.1 ES (Extended Surround) there is a center rear surround channel added. It can be matrixed, which is decoded from the left and right surround channels or a separate discrete channel which is encoded on the DVD. Even when there is a discrete rear surround channel the same information is matrixed in the left and right surround channels for compatibility with 5.1 systems. Equipment that have a 6.1 decoder will subtract the rear surround information from the left and right surround channels to restore them to discrete channels. The 6.1 systems you can currently buy will develop the center surround channel in much the same way as the Pro-Logic systems developed the front center channel when the discrete rear surround channel is not present. Since the source is digital, the decoder can be much more precise. Since there is naturally occurring matrixed information in Dolby 5.1 encoded DVDs, quite often the decoder will supply information to the rear surround channel, thus improving even 5.1 encoded discs. Currently there are not any sources for 7.1 systems, although it is expected to be the next generation of theater sound. The 7.1 systems will have left and right surround channels as well as left and right rear channels and the rear center channel. Again the systems available today will just develop these additional channels from the 5.1 channels of the source. Last edited by rbinck; 08-02-2005 at 03:32 PM. Reason: Clarified the 6.1 and 7.1 information |
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#2 | |
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Miss-Ti, World's BEST Cat
Join Date: Feb 2005
Location: Lancaster, PA
Posts: 1,817
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#3 |
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High Definition is the definition of life.
Join Date: Mar 2005
Location: vermont
Posts: 902
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man are you out of date, i have a 6.1 system,and there a lot of films in 6.1 and some films are listed as 5.1 but will decode as 6.1. in fact with hdvd and blu-ray coming soon those players will have dolby digital + up to 13.1!!! man get up to date!!
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#4 | |
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Miss-Ti, World's BEST Cat
Join Date: Feb 2005
Location: Lancaster, PA
Posts: 1,817
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Quote:
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"Miss-Ti, World's BEST Cat!"
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#5 |
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Administrator
Join Date: Apr 2004
Location: Katy, Texas
Posts: 12,335
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Don't just throw bombs! Tell us details and furnish links. Many decode to 6.1 because the receivers are doing the work as explained. I don't mean to call your baby ugly, but I don't know of any discrete 6.1 or 7.1 sourced DVDs. If you do give us a link and I will update. I know the standard exists for the extra track.
There are several DTS 6.1 ES which are matrixed. The Lord of the Rings being one I can think of off hand. Edit: Cat if you have an old Pro-Logic surround amp laying around, you can feed the left and right surround signals from your 5.1 system to let the Pro-Logic amp develop the center rear channel. It is not as good as the 6.1 systems because it is analog decoding vs digital, but it does sound pretty good. Last edited by rbinck; 07-30-2005 at 10:44 PM. |
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#6 |
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I Love old movies
Join Date: Jul 2005
Location: Florida
Posts: 11
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Thanks for the information, rbinck. I am in the process of setting up surround (or maybe non-surround in my case) for my Pan. 50LC14. I have an old Sony Pro Logic STR DE-405, and yep, the manual says the rear speakers are mono.
The room I'm putting it in has no way to connect the rear channel (cath. ceiling, fireplace on one side and open space on the other) unless I want to go wireless - hardly seems worthwhile for a mono rear. I might not even use a center channel as the receiver has a "phantom" center channel which seemed to sound pretty good when tested. I am using Bose 301 series II speakers and they didn't seem very compatible with a couple of center channel speakers I tried. I actually like the sound from the TV (don't laugh!), except for the lack of deep bass. I'm not sure whether it's worth it for the hassle of yet another component and remote. I also need to connect it so that It will default to tv sound. I am using a Pace dc550p HD box. Anyone have any comments or suggestions - other than buying a new 5.1 system? Cheers! |
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#7 |
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Administrator
Join Date: Apr 2004
Location: Katy, Texas
Posts: 12,335
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Surround, it should be noted is an effects channel. It should not be confused with a four channel system intended to place sounds anywhere in the room. The standard placement of surround speakers is on the side walls at your seating position, not behind you. That is why they are called surround as opposed to the rear. There can be a center channel placed in the rear center and left and right rear speakers placed behind you as well in the 7.1 systems. These channels will most likely be matrixed as opposed to discrete. After all the movie producers want your attention primarily ccentered on the screen not what is sneaking up behind you.
Now it does seem that there are some DVDs that are encoded with a discrete center rear channel. I found a list at http://www.dvdtherapy.com/dts_list.php, so it seems as though tvine2000 had a point in post #2. I'm not sure it was a life and death thing or anything like that, like the tone of that post seemed to be, but maybe tvine has spent too much time on other forums where the standard practice seems to be playing gotcha. Last edited by rbinck; 07-31-2005 at 02:58 PM. |
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#8 |
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OTIS,,me hero
Join Date: Jun 2004
Location: Someville TN
Posts: 4,554
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Thanks for the insight Rbinck, as usual, you intimidate me with your knowledge. I did a little tinkering with my 2 sound systems. My computer has an older Hercules 7.1 (which I love) sound card in it. I also have a cheap set of Creative 6.1 speakers. I played the movie "21 Grams" and did notice a "little" enhancement to the sound quality of the movie due to the rear center. I then played it in my home system (Aiwa receiver 5.1 + dts - jensen center, sub & rears with jbl pro-monitors up front). I then asked the wife and son to watch the movie on both systems (without telling them what I was doing) but asked them to pay particular attention to the sound. They both concurred that they could not tell a difference (other than the obvious jbl pro-monitors). I then told them what I was doing and they listened again - with conflicting opinion. My son thought the 6.1 was an added bonus when my wife vehemently said that the rear center was a distraction. In conclusion - I started a fight at Oblioman central.
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#9 | |
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Miss-Ti, World's BEST Cat
Join Date: Feb 2005
Location: Lancaster, PA
Posts: 1,817
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Quote:
__________________
"Miss-Ti, World's BEST Cat!"
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#10 |
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Administrator
Join Date: Apr 2004
Location: Katy, Texas
Posts: 12,335
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By setting the rear center surround channel to off, the information for that channel will be equal in both the left and the right surround channels. This will have the effect of "centering" that information between the left and right surround channels. Since the information is surround effects as opposed to the voices as it would be in the front, the necessity of having the physical speaker there is not as much as it is for the front center channel.
I'd guess you may only notice a small amount of difference, if any, by adding the 6th. speaker, so I guess I agree with you. To me the only channel I wish they had they don't is a tactle LFE channel for the tactle transducers, like the Buttkickers. For me and my wife it is annoying to get the tactile vibrations with music and I think if it only came in with explosions and other things that would vibrate you it would be better. Not much of a chance that will happen though as they don't put tactile transducers in theaters much and that is the driving force for all of the surround technologies. Last edited by rbinck; 07-31-2005 at 09:04 PM. |
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#11 |
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My plasma is High Def.
Join Date: Jun 2005
Location: San Diego
Posts: 5
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My wife bought me a HK 5.1 receiver for Christmas. I don't think she knew what she was gettting me into. She just wanted to replace the old receiver from 1960. Now I've got the 5.1 setup and when its off and we just have the TV speakers on she thinks the TV alone sounds like crap. For those of you who have not tried 5.1 its awesome. I was watching Jurassic park last night and in one of the jungle scenes if I closed my eyes if sounded like I was in the middle of a rain storm. Now if I can just swing the $$ to get a 42 inch HD monitor to go with my sound system....
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#12 | |
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Miss-Ti, World's BEST Cat
Join Date: Feb 2005
Location: Lancaster, PA
Posts: 1,817
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Quote:
But seriously, have you ever seen "Hulk" since you got the5.1 setup? It starts out slow, but about an hour into it there are some awesome sound effects. Can anyone recommend other "can't miss" movies with great audio to match the video?p.s. If you're hoping for a plasma, ask Mrs. Clause for a 50" to get the true 720p HD effect without scaling the 1280 down to 1024. Plus it's a lot more square inches of "awsomeness" (almost 42% more) Width Height Width Sq Height Sq Sum Sq Root (Diagonal) Area (WxH) 43.579 24.513 1899.129241 600.887169 2500.01641 50.0001641 1068 36.607 20.591 1340.072449 423.989281 1764.06173 42.00073487 754 Difference 314 Percent More 41.6446%
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"Miss-Ti, World's BEST Cat!"
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#13 |
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Who needs reality?
Join Date: May 2005
Location: Kentucky
Posts: 436
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Gotta love Pearl Harbor DTS for the initial fly-by scenes of the Jap Zeroes. Later there are the .50cal guns behind you and to the sides while torpedoes are zinging from left to right and bullet ricochets all over the place. Will definately have you looking over your shoulder.
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Blue_Tech ![]() Sony KV32XBR400 Sony DVD Dream 5.1 system Sony PS2 DishNet 522 Dual Tuner DVR |
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#14 | |
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Miss-Ti, World's BEST Cat
Join Date: Feb 2005
Location: Lancaster, PA
Posts: 1,817
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Quote:
__________________
"Miss-Ti, World's BEST Cat!"
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#15 | |
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Who needs reality?
Join Date: May 2005
Location: Kentucky
Posts: 436
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Quote:
__________________
Blue_Tech ![]() Sony KV32XBR400 Sony DVD Dream 5.1 system Sony PS2 DishNet 522 Dual Tuner DVR |
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