Proper Surround Loudspeaker Placement
Dear Gary:
This letter is a follow-up to one written several months ago regarding the proper placement of surround loudspeakers. Judging from several Blu-ray reviews written since then, it appears that your set-up is still not correct.
Despite your assertion that your set-up is recommended by both DTS® and Dolby®, I have been to numerous home theatre Web sites, including DTS and Dolby, as well as THX®, and all seem to agree on a set-up that differs from yours.
According to DTS, Dolby, THX, and numerous other home theatre sites, the surround loudspeakers in a standard 5.1 set-up are to be placed at the sides of the sweet spot listening position and aimed inward at an angle of 90 to 110 degrees??not at the back sides of the room. Ideally, they should also be placed at least two feet above the listening spot to maximize ambience. The additional back surround loudspeakers in a 7.1 set-up belong at the back of the listening position, aimed inward at an angle of 135 to 150 degrees??not at the sides.
Further exploration at the home site of Wendy Carlos (www.wendy
carlos.com)??whose research into the psychoacoustics of surround sound led to the placement of
surround loudspeakers at the sides??reveals the technical reasons as to why the surrounds belong at the sides. In your set-up, the side surrounds are aimed from the back toward the center. There is nothing that sounds like it is coming from the sides (i.e., no sidewall imaging), and any back surround imaging is narrow and weak.
For a better and more comprehensive explanation of this, visit http://wendycarlos.com/gosurround.html and skip to the section: ?The Main 5.2 Channels.? It describes proper loudspeaker placement of a standard 5.1 set-up, as well as examines classic blunders, and it explains the reasons behind everything based on Miss Carlos? extensive research on the subject.
Frank Freline
Editor-In-Chief & Publisher Gary Reber Comments:
I disagree. You apparently are not seeing the ?Standard? setup recommended by DTS and Dolby; see http://www.dts.com/Consumer_Electronics/Home_Theater/Speaker_Layout_and_Configurations.aspx and http://www.dolby.com/consumer/setup/speaker-setup-guide/index.html.
As a pioneering multichannel recording producer and engineer since the late 1970s, I have had a great deal of experience in using 4.0 to 7.1 audio setups. I have written extensively over the past 19 years about this subject in Widescreen Review. Both DTS and Dolby subscribe to the 7.1 setup we use (there are other setups identified on their respective Web sites, but they are not optimized for spatial coherency). THX advocates dipole surrounds mounted high up near the intersection of the ceiling and wall positioned 90 degrees relative to the ?sweet spot,? with the surround signal dispersed out-of-phase. I do not subscribe to this approach.
(Second e-mail)
I have seen those pages at Dolby and DTS. The placements are exactly as I described to you before. However, based on your most recent Blu-ray reviews, you seem to have your surround loudspeakers wired differently than the diagrams illustrate. Ultimately, it all comes down to taste and preference, but I very much prefer the set-up that mirrors those of conventional cinemas. That ensures that I am listening to the soundtrack as was originally mixed.
(EditorGary?s Comments)
The problem is that the studios are mixing either with the ?standard? side channels (preferred) layout for the added two channels (Bambi, How To Train Your Dragon, Monsters, Dances With Wolves, Fantasia & Fantasia 2000, the Shrek Series, The Sound Of Music: 45th Anniversary Edition, Beauty And The Beast, Toy Story 2 & 3, Ice Age: Dawn Of The Dinosaurs, Snow White And The Seven Dwarfs: Diamond Edition, Saw 3D, Punisher War Zone, Chris Botti In Boston, etc.).
Or the ?rear surround? layout for the added two channels (The Next Three Days, Highlander & Highlander 2, For Colored Girls, Buried, The Last Exorcism, The Expendables, The Rocky Horror Picture Show, Killers, Kick-Ass, From Paris With Love, Daybreakers, Saw V & VI, Gamer, Stargate, Crank 2: High Voltage, Star Trek Motion Picture Series, My Bloody Valentine 3D, Transporter 3, etc.).
There are many more examples of the two distinct approaches that can be found and identified by reading our Blu-ray sound reviews. We have reviewed over 90 Blu-ray titles with 7.1-channel soundtracks.
The problem is that the studios are not indicating what layout they are using on the Blu-ray packaging or in the audio setup menu on the discs. Therefore, if your system layout is not the one the content was mixed in, you will hear it wrong??the spatial relationships will be wrong. We can tell (not always correct) because we have sophisticated monitoring equipment that lets us know where the two added channels have been placed, and therefore, we can re-wire our reference system to shift the signals??re-wiring the surround channels normally positioned to the back sides to the 90-degree position and wiring the normally positioned surround channels as the added two back channels (?rear surround?), if that was the mix layout, or leaving the system untouched when the mix was done in the 7.1 ?standard? preferred layout with the added two channels positioned 90-degrees relative to the ?sweet spot? and the normally positioned surround channels left unaltered.
The ?standard? preferred layout organizes the seven full-range channels equidistant and in six 60-degree segments relative to the ?sweet spot? for optimized phantom imaging between each hard signal channel??thus the means to achieve a coherent, seamless holosonic® soundfield mix. Drawing an imaginary line connecting the loudspeaker positions forms a perfect 360-degree circle. The ?rear surround? layout loads up the rear hemisphere of the soundfield, thus degrading sidewall imaging, due to the large, non-equal distance gap between the rear surround loudspeaker position (left or right rear) and the respective front loudspeaker position (left or right front).
This is very confusing for the end user (and for us as well).
You can E-mail Widescreen Review @ editorgary@widescreenreview.com