pyroponic Posted July 17, 2005 Share Posted July 17, 2005 Current system: TV: Panasonic 50" LCD HDTV DVD player: Denon DVD-2900 Amplifier: Rotel RMB-1095 (200x5) Preamp/processor: Rotel RSP-1068 Fronts: Klipsch RF-7 Surrounds: Klipsch RB-75 Center: Klipsch RC-7 Subwoofer: Klipsch RSW-15 Thinking about adding on a Rotel RB-1080 (200x2) and putting two more Klipsch RB-75's in the rear (bookshelves), is it worth it? Thanks Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted July 17, 2005 Share Posted July 17, 2005 personally, I think it depends somewhat on the size of the room. Would there be sufficient space for true side surrounds that are physcially distant enough from rear surrounds that your ear could tell the difference? Michael Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 17, 2005 Share Posted July 17, 2005 It's very room dependant. In fact, 6.1 will probably sound better than 7.1 if you have a rather small space. Quote Link to comment Share on other sites More sharing options...
sfogg Posted July 17, 2005 Share Posted July 17, 2005 "In fact, 6.1 will probably sound better than 7.1 if you have a rather small space." 6.1 is psychoacoustically a bad idea. A person can mishear a sound coming from directly behind them as coming from in front. The rear to front inversion is totally the opposite of what is intended by having a rear speaker. Two wider spaces rears (7 speakers) help to avoid that, even more so if they aren't duplicating mono rear material. Shawn Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 19, 2005 Share Posted July 19, 2005 ---------------- On 7/17/2005 3:40:33 PM sfogg wrote: 6.1 is psychoacoustically a bad idea. A person can mishear a sound coming from directly behind them as coming from in front. ---------------- Wouldn't you also have the same problem with front center? (implying that I don't think it's an issue) At least I haven't noticed any problems with the location of sounds coming from rear center. I don't like the idea of 7.1 because both channels share a lot of the same info which means comb-filtering issues when sitting off-axis. Though I can see it being a worthy compromise when the extra coverage is needed in a wider room or when the listening position is near the back wall. Quote Link to comment Share on other sites More sharing options...
Zen Traveler Posted July 19, 2005 Share Posted July 19, 2005 ---------------- On 7/19/2005 3:11:16 PM DrWho wrote: ---------------- On 7/17/2005 3:40:33 PM sfogg wrote: 6.1 is psychoacoustically a bad idea. A person can mishear a sound coming from directly behind them as coming from in front. ---------------- Wouldn't you also have the same problem with front center? (implying that I don't think it's an issue) At least I haven't noticed any problems with the location of sounds coming from rear center. I don't like the idea of 7.1 because both channels share a lot of the same info which means comb-filtering issues when sitting off-axis. Though I can see it being a worthy compromise when the extra coverage is needed in a wider room or when the listening position is near the back wall. ---------------- I read the same article that I believe sfogg got his information from in Sound & Vision magazine. I thumbed trough the last several issues but couldn't find it. If I remember correctly the situation he is talking about happens behind us because of the shape of the head. It doesn't happen in front of us because of the shape and position of our ears facing forward. I have a 7 channel set up. I never tried the 6 channel route so I can't speak from experience. I like the way my set up sounds, but going from 5.1 to 7.1 wasn't as dramatic as I would have hoped except for some passages on certain 6.1 movies. For high quality DVD Concerts and music videos (Peter Gabriel comes to mind) it also adds to the entertainment value. Just wanted to add another opinion insofar as the upgrade was concerned. Does it make a difference? Yes. Does it make a drastic difference on most material? IMHO, No. Quote Link to comment Share on other sites More sharing options...
Zen Traveler Posted July 19, 2005 Share Posted July 19, 2005 ---------------- On 7/19/2005 3:11:16 PM DrWho wrote: ...Though I can see it being a worthy compromise when the extra coverage is needed in a wider room or when the listening position is near the back wall. ---------------- BTW-I also remember reading somewhere that in a 7.1 set up it's better to have the rears 3 to 4 feet apart, instead of wider--I think that was in my Denon manual. Quote Link to comment Share on other sites More sharing options...
Yesfan70 Posted July 19, 2005 Share Posted July 19, 2005 If I had the funds and the room for them, that's probably what I would do. Just buy another pair of the RB-75s and go 7.1. I agree with the others though, that it is not as dramatic as going from stereo to 5.1, but it is still noticable none the less. Quote Link to comment Share on other sites More sharing options...
sfogg Posted July 19, 2005 Share Posted July 19, 2005 "Wouldn't you also have the same problem with front center? " No... if you mishear a thing from the center line of a listener as being in front a front and center speaker will be heard as coming from in front. "(implying that I don't think it's an issue) " There is a lot of research on the subject.... Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted July 19, 2005 Share Posted July 19, 2005 "I read the same article that I believe sfogg got his information from in Sound & Vision magazine. I thumbed trough the last several issues but couldn't find it." I haven't seen that article. If you find it let me know as I'd like to read it. Lexicon has been pushing for two rear speakers (with stereo information) for nearly 10 years because of this reason. Shawn Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 19, 2005 Share Posted July 19, 2005 in middle school we did an experiment during an open house where you stood inbetween two speakers, one directly in front and one directly behind and we were testing how well people could tell which one the sound was coming from. Basically the data showed that people were unable to accurately decipher which speaker was playing. So I'm curious as to what other research is out there that contradicts the simple childhood experiment. I know it was just a silly experiment, but all my readings have always indicated the same things so I would very much enjoy reading these articles if you have them available. Quote Link to comment Share on other sites More sharing options...
sfogg Posted July 20, 2005 Share Posted July 20, 2005 "one directly in front and one directly behind and we were testing how well people could tell which one the sound was coming from. Basically the data showed that people were unable to accurately decipher which speaker was playing. " And where you also playing video which corresponded to what was playing? When the center channel is playing you typically have a visual which matches up up in front and even if it doesn't it still biases the perception to the front. "So I'm curious as to what other research is out there that contradicts the simple childhood experiment. " See down a ways in this post... http://www.avsforum.com/avs-vb/showthread.php?p=4130623&post4130623 There is more then this, I'll see if I can find the references to it. Some of it was done by the military as I recall having to do with battlefield confusion. Shawn Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 20, 2005 Share Posted July 20, 2005 I think this guy made a really good argument so I decided to copy it over. At least it totally changed my opinion (and now I'm going to be looking for rear channel info sounding like it's coming from the front). I haven't noticed it yet, but who knows... _________________________________________________________ ------------ Originally posted by misterHT In a small ( < 12 x 15 ) room, 7.1 is completely unnecessary. Cramming in those extra speakers just for the sake of getting a MATRIXED 7.1 mix, serves to do nothing more than contaminate the soundstage. PERIOD! ------------ This is flat out wrong, and all the uppercase characters and other chest-thumping punctuation won't make it right. In the first place, whether matrixed or discrete, rear content benefits from speakers in the rear. Room size has nothing to do with it. A properly set-up 7.1 system will improve on a properly set-up 5.1 system every time. This is why Meridian and Lexicon and Fosgate have designed their cutting-edge pre-pros around 7.1 speaker setups (not 6.1) for over a decade, and, more importantly, why Dolby, THX, and DTS have all followed their lead with respect to playback of encoded rear content, even when that content is mono. Nor will you find any published research to support your claim, although there is extensive research supporting the improvements of a second set of surround speakers. This sour grapes argument that 7 speakers are unnecessary has been perpetuated in one form or another since the roll out of Surround EX as a home theater standard. The fact remains that the reason for using two pairs of rear surrounds is grounded in a solid body of psychoacoustical research that clearly establishes why a 5.1 speaker configuration is inadequate when attempting to create a seamlessly immersive soundfield. This has been well-known in audio engineering since the definitive work by Theile and Plenge, as reported in their paper Lateralization of Phantom Sound Sources, published in the Journal of the Audio Engineering Society, April 1977. Their tests into side panning and phantom imaging effects showed quite conclusively that due to differences in the way we hear sounds originating from the side vs. the front, if we attempt to create phantom images at the sides using only front and rear speakers, the images are highly unstable. Their conclusion is that: in the search for a loudspeaker arrangement that allows for all round effect, the directions right and left on the lateral (90 degrees) must be represented through real sources. In other words, stable side imaging *requires* a *real* pair of speakers placed directly to each side of the listener. It is easy enough to demonstrate this fact for yourself in any system or room. Sit or stand in the sweet spot, and play a mono source through your two front L&R speakers--youll hear a typical stable phantom center image. Now turn 90 degrees, so that one ear is pointed towards that phantom center--rather than remaining locked to a fixed location, the image will break apart. Hence the reason why a pair of physical speaker is needed directly to the sides of the listening position. Of course, placing the side speakers at 90 degrees inevitably leaves a huge gap in the rear soundfield. That is why many 5.1 speaker setups have the surrounds positioned farther behind the listening position. The popular speaker placement at 110-degrees is a compromise that narrows (but does NOT eliminate) the rear hole, but this partial improvement comes at the expense of seriously weakened side imaging, because of the problem described above. Thus, there is no way to achieve a seamless soundfield using only one set of surrounds. Dr. Robert E. Greene wrote a very cogent article explaining the inherent limitations in attempting to create surround with only 5 speakers in The Perfect Vision, Issue 30. May/June 2000. Adding a second pair of surrounds for a 7-speaker setup solves this problem handily. The sides can be placed at 90 degrees for stable side imaging, the rears can be placed at 150 degrees to close the rear gap, and voila!--seamless, smooth envelopment. This is why home surround processors from manufacturers with expertise in psychoacoustics (Lexicon, Meridian, and PL II developer Jim Fosgate) have been building their technologies around 7-speaker configurations for many years. This is also why in developing the Surround EX format, THX and its Pro-Logic II partner Dolby Labs adopted a 7-speaker configuration for an immersive soundfield. There may be some rare atypical rooms unable to benefit from an extra set of surrounds (I havent heard any, but Im willing to concede the remote theoretical possibility), but that is no logical justification for a blanket assertion that a 5.1 system is preferable in small rooms. Once you know what to listen for, the ambient envelopment which makes up 99% of a film soundtrack (rain, wind, traffic, crowd noises, etc.) will never sound realistic because of the soundfield gaps that cannot be solved with only 5 speakers. And of course you use the intended directionality of EX and ES rear channel effects that are specifically encoded to be extracted and reproduced from the rears. That isnt opinion, it is simply long-established scientific fact. Turning now to the issue of 6.1, or use of a single rear center speaker, even DTS advocates using two rear speakers for its ES 6.1 DISCRETE format. The reason is grounded in a substantial body of psychoacoustic research dating back to the 1970s showing that 6.1 configuration is inherently flawed. In the first place, our hearing behind us does not mirror the acuity of our hearing in front. Quite the contrary--sounds that originate along the median (center axis) plane between our ears, whether from above or directly behind are extremely difficult to place accurately, and not just because of those fleshy appendages called ears that sit between us and the sound source.. In large part, this reduced localization ability is due to the lack of certain fundamental localization cues, such as slight timing offset in the arrival at each ear, that are present when sounds originate from one side or the other. The result is the localization problem known as "back-to-front reversal," in which we actually hear sounds from directly behind as coming from in front of us. In an ambiguous situation, we "hear" the sound from the front center because that's where the focus of our visual field is, and basic survival instinct has taught us to give it more of our attention. There are certain sounds, such as voices, that we expect to hear coming from in front of us, so we do. And when we're watching a film with an EX soundtrack, our attention is firmly fixed ahead, hence we're even more susceptible to the auditory confusion. The research documenting this phenomenon is abundant, but you don't have to take my word for it; here are some references to get you started: Butler, R.A. and K. Belendiuk, "Spectral Cues Utilized in the Localization of Sound in the Median Sagittal Plane," Journal of the Acoustical Society of America, 61 (1977); Morimoto, M. and H. Aokata, "Localization Cues of Sound Sources in the Upper Hemisphere," Journal of the Acoustical Society of Japan, 5 (1984); Musicant, A.D. and R.A. Butler, "The Influence of Pinnae-Based Spectral Cues on Sound Localization," Journal of the Acoustical Society of America, 75, (1984); Kuhn, G.F. "Physical Acoustics and Measurements Pertaining to Directional Hearing," in Directional Hearing, edited by W.A. Yost and G. Gourevitch, 3-25. New York: Springer-Verlag, 1987; and Wightman, F.L. and D.J. Kistler, "The Dominant Role of Low-Frequency Interaural Time Differences in Sound Localization," Journal of the Acoustical Society of America, 91 (1992). The reversal problem tends to be contextual--what we expect to hear has a lot to do with where we place sounds. Not all sounds will get incorrectly localized, but some will, and that is even more problematic because only hearing some of what are meant to hear from behind lulls us into thinking we are hearing the soundtrack correctly, wheresas we can never be sure whether we are or not. So, in light of this problem, we can now see that far from being MORE accurate, even with discrete rear channel content, the use of a center rear speaker in a 6.1 speaker configuration is actually FAR LESS accurate --unless your definition of accuracy is hearing a sound coming from the opposite side of the room from where it's meant to be heard. The back-front reversal problem disappears, however, when using two rear speakers placed off the center axis. This is precisely the reason why both THX Surround EX and DTS ES mandate the use of TWO rear speakers, even when they're only reproducing the same mono rear content. Which brings us to: ------------- Cramming in those extra speakers just for the sake of getting a MATRIXED 7.1 mix, serves to do nothing more than contaminate the soundstage. ------------- Wrong again. Lexicon's Logic 7, Dolby PL IIx, and Meridian's Trifield do not "synthesize" their additional channels, they extract them from the contents of other channels using cues that are part of the recording itself. Nor do they use simple Dolby Pro-Logic phase decoding algorithms to determine the content of these additional channels; rather, they apply quite sophisticated correlation processing using the contents of all other channels in order to determine very natural and convincing steering. There is nothing "contaminated" about the soundfield created by Logic 7, PL IIx or Trifield; on the contrary, as I explained above, a 7.1 speaker set up is the only way to plug soundfield gaps for convincing surround, and the addition of stereo rears puts these processes ahead of the mono rears produced by EX and ES. If I'm listening to a car pan across the front right to left and continue into the side left, which would be the more natural way to continue steering it: into the left rear or have it suddenly jump into both rears? Cheers, Philip Brandes ________________________________________________ http://www.avsforum.com/avs-vb/showthread.php?p=4130623&post4130623]http://www.avsforum.com/avs-vb/showthread.php?p=4130623&post4130623'> Quote Link to comment Share on other sites More sharing options...
boomer9911 Posted July 23, 2005 Share Posted July 23, 2005 Is there a format released in ACTUAL 7.1 on DVD...thanks. what flicks are available?!.... PS. I hope your a speed typer DRW....OUCH.... Quote Link to comment Share on other sites More sharing options...
Zen Traveler Posted July 23, 2005 Share Posted July 23, 2005 ---------------- On 7/23/2005 1:53:51 AM boomer9911 wrote: Is there a format released in ACTUAL 7.1 on DVD...thanks. what flicks are available?!.... PS. I hope your a speed typer DRW....OUCH.... ---------------- No. Right now there is either, DTS-ES which does have a discrete (actual) rear channel (6.1) and Dolby Digital-EX which matrix's (uses material from the surround Left & Right) to make a rear channel. The last part of this thread has to do with which is better for recreating those formats, one or two rear speakers. Some receivers also allow 5.1 material to be "matrixed" into a 6.1 format. Quote Link to comment Share on other sites More sharing options...
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