Looking for help on speaker placement

[MattCXII]

I am going to be tackling this problem very soon. I just bought a house with a move-in date of Dec. 17th. The basement is unfinished and I can't wait to get making it into a dedicated home theater room. I don't have the demensions yet but Andrew, what are the recomended demensions for your rears when setting up either a 6 or a 7.1 system? I didn't know distance played that much of an impact. Please let me know as this will be one of many questions I will have about my theater as it developes.

Thanks,

Matt

[Andrew Pratt]

Matt Dolby has this image on their website that should help get you started. If you do a 6.1 system just mount the 6th channel directly behind your sweet spot.

[Burke Strickland]

If you have a choice between 6.1 and 7.1, (e.g., you can afford the extra speaker, your electronics support it and you have the space in your listening room) go with 7.1.

There is a nasty psycho-acoustical effect noted by some folks who have listened to 6.1 systems whereby the sounds coming from a single rear speaker appear to be coming from the front, which pretty well destroys the immersive, seamless surround effect. Having two speakers at the rear, even if only slightly separated, overcomes this phenomenon, and the sound is perceived as coming from the rear even if the two speakers are playing the exact same signal.

Many systems vary the signal to two rear speakers slightly to help eliminate the possibility of "combing", or cancelling out of some frequencies that sometimes is noticable when more than one speaker is playing the same signal -- an effect that would be much more apparent if two speakers were used in the front channel where most of the dialog and a lot of other prominent aspects of the presentation are concentrated, as opposed to the ambient sound and special effects that typically come from the rear.

So there is little risk and much to gain by going with 7.1.

Enjoy -

Burke

[BlazeMaster]

I noticed in the diagram above on Dolby's Digital EX....does the same go for PLIIx also? The sub was shown in the picture between the left and center speaker, this the first time I noticed anything about the sub. Why did they recommend to put the sub there? Is it because it's less localizable over there? Can I also place it between the right and center speaker as well?

The picture also only showed the angles that they should be placed at...what about distance between the speaker and the listener to achieve those angles? I've heard from other members that the surrounds should be about 2-3 feet behind or away from the listener. Can someone verify this for me?

[junior77blue]

I really don't think distance is that critical...since

1) time alignment through distance is done with most (all) processors
2) you then dial in each speaker to the proper level as well

granted you shouldn't have the speaker immediately NEXT to you...but