Spall's Home Theater - Basement Build - Page 2

Here's how you can fully understand my position ... It is your room, it is not my room. My job is to tell you the pros and cons of doing (whatever it is) vs some other way, so you can make an informed choice in such matters. It is very easy to pull an "oh oops" and many of those oh oops will be expensive to fix (usually more than my fee) or provide a lifetime a negative karma in your room. And, yes. above the screen but aimed down toward the seating positions.

Now...there is another advantage to that. The difference in distance between the ears in the first row to the speaker and the ears in the second row to the speaker is reduced. Because that difference is less, the difference in SPL between row one and row two is also reduced ... that is a good thing.

Can this be corrected by adjusting the channel-specific level balance in one's AVR? Most go up to +/-15 dB or so, don't they?

Also, if the center channel is "closer" to the audience, wouldn't it also be closer than the front L/R speakers, so they would have to be adjusted also?

No, that would adjust the volume at the speaker. What you want to do is minimize the the difference in SPL between each row of seats. To do that, you need to reduce the difference in distance between the speaker and each row, and/or, move the speakers further away from the seating area (approx 6dB decrease with each doubling of distance). For example, the difference in direct sound between rows at 5' and 10' would be 6dB, between 10' and 15' would be ~4dB but between 15' and 20' would be 2dB. (Direct sound intensity decreases inversely with the square of the distance, or I = 1/d**2 )

Thus minimizing the difference in distance from the speakers and/or increasing the distance from the speakers will minimize row to row variances in SPL. This comes significantly into play where the back row of seats is very close to the back wall (rear surround speakers) or you place seats too close to side walls (side surrounds). You now have the effects field completely overwhelming the L/C/R at the expense of intelligibility, clarity, focus, and sound stage width/depth.

That depends on a long list of factors. When all weighted together, behind generally wins with above coming in second.

The biggest reality of going to an AT screen is the reality that someone, somewhere, at some point is going to try and scare you into not doing it. There's your reality.

Here are some other realities:
1. Loss of light reflected back into the seats from the screen. True fact. You can measure the difference between 22 ft lamberts but you cannot tell the difference between 22ft Lamberts and 20 ft lamberts.

2. Loss of image quality. Nuts. If you are outside the range where visual acuity doesn't allow you to resolve the holes in the screen, you are also outside the range of human visual acuity actually seeing any loss of picture quality (I suppose if someone can hear the difference between bzillion dollar speaker wire and lamp cord, I suppose they could also see a pion with their naked eye.)

3. Moire. Yup. Was a problem once. Not a problem any more.

Let's see now. If human visual acuity isn't going to let you see the difference between an AT and non-AT screen, but your hearing will hear all the problems with a non-AT screen, do you really have a choice?

Do it! (keeping with the tradition of heartily endorsing anything I'm doing)

One thing to consider is whether you'll be implementing CIH using the "poor man's" approach (zoom), or a lens. My choice is using zoom (PT-AX4000). Then there's masking - personally, I'm not going to worry about masking until after I have everything else working properly. You'll also want to research projector mounting distance and height carefully, since there are additional variables being introduced into the equation (a lens if you go that route, or finding a mouting distance and vertical offset that works for both 16:9 and 2.35:1 zooms).

I wouldn't worry too much about the space above and below. I've seen screens right up against the ceiling (like mine!) and many have them much closer than 36" from the floor, with 26" or so being the lowest I've seen (mine is 27").

If you're able to apply some sort of anti-reflection treatment to your ceiling (triple black velvet or telescope flocking, or can paint it flat black, then you'll be in good shape.

But I agree that 99" width seems too narrow for a good screen.

Spall, when I first started out with my build it was my intention to do the speakers on the sides and center (bottom) flanked around a fixed screen. I was convinced this was the best way to go for not only audio optimization but also for video. Indeed, a local shop I was getting an estimate from refused to even do AT screen installs. In the end, after much research and endless hours on this forum, I decided to go AT as well as CIH. I have zero and I mean zero regrets going this route. Not only did I get a bigger screen (with the speakers behind) but having the sound come from the screen is much more important to me than I realized. I don't feel like I've compromised on the audio or the video at all. In fact, I'm blown away by the whole set-up.

One thing, however, that I did not know with CIH is that a lot of movies are not 2.35 so often you get the white space on the left and right sides. And a few will result in minimal bleed onto the frame.

As far as having the speakers so close up against the back row, I've got a similar set-up as well due to room limitations. Suggest going with dipoles instead of direct firing since the row is so close to the speakers.

Good luck!

Well, do I give you the answer or let you worry about the additional expense and loss of sound isolation? Hum .....

Look at the manufacturer's frame, mounting, and fabric installation process. If you ponder it long enough, you'll find it will be very easy to remove either screen or the fabric to gain access to behind the screen wall ... both those times in 5 years that you'll really need to.

It's just a whole bunch easier to remove the screen than to build a doorway.