Axiom Home Page Forums General Discussion Home Theater rear QS8 in 7.1 placement? How far apart?

Hey guys, I am finishing up wiring my dedicated home theater. The dimensions are 16'6"x22"6'. I already own the M60s and will be buying the VP150 and 4 QS8s for surrounds in a 7.1 set up. I am planing on setting up the side QS8s to the left and right of the main seat at at about 6' off the ground.

The back of the theater will have an additional row of 4 seats on a 12" riser. I will probably mount the 2 rear QS8s 5' from the top of the riser to equal the side QS8s.

How far apart from each other is optimal for two QS8s in a 7.1 setup?

Thanks!

If there's room they should be as far apart as the distance to the rear of the listening area. If that distance is too extreme, either far or near, then they should be placed at about the edges of the listening area. For instance, I have my rears a few inches wider than the arms of the couch (which is also the distance to the back of the couch, I'm just lucky with my room dimensions).

Ok, so this is going in a dedicated theater. I can place them anywhere as I have yet to drywall. The theater will have 2 rows.

The THX website has them almost beside each other. Dolby website has them about 1/3 of the room apart?

Hi sotwell,

I'd go with the Dolby recommendation, or perhaps use a bit more separation. But understand that because of the QS8's multi-directional dispersion, it's not all that critical. They're generally very forgiving in terms of placement. Just keep them out of the corners.

You could experiment, using a couple of stepladders to temporarily postion them and see if there's any significant difference in soundfield envelopment with different placement. In my experiments using two side QS8s in a 5.1 setup in my room, I found it very difficult to discern any difference when I moved the QS8s forward or more to the rear. Differences in height of the two surrounds made very little difference, if any. Of course, every room is different but I think you'll find placement very flexible.

Regards,

Also, THX allows for greater distances. In my THX setup menu, I have mine set to 1-4 ft. The other options are <1ft or >4ft. So even if you decide to use a THX listening mode, the distance won't matter.

Sot, as Chris indicated, the general idea should be to use the same separation rule as is applied to the mains: the separation should be about as much as the distance that they're behind the listening position. At a minimum(unless special THX processing is in effect)the back surrounds should be outside the listening area both to the left and right, so that both a back left and back right effect can be heard by all listeners when the material contains those effects.

okay, so under that scenerio, my rear row of theater seating (riser dedicated theater)will measures 145". So should my rear QS8s measure 145" apart? The rear wall measures 195" so I should mound the QS8s 25" from each wall?

My screen will be 130" (132" diagonal) wide so my front M60s will be spaced 130" apart.

Yes, so that even someone sitting in the farthest seat to the left will have a back speaker to his left and similarly for someone in the seat farthest to the right.

Great, thanks for the help.

One more question. The room is 16'5" wide. My screen will be 132" wide. Is 135" or so to far apart to seperate M60"s? Prime seating will be about 15' back.

As was indicated in my first reply, a good general rule is that the main speakers should be separated about as much as the distance from them to the listening position. So, even a bit more than 135" could be justified.