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Questions about Speaker placement behind screen....

Discussion in 'Home Theater Projects' started by Hosmackin, Aug 28, 2010.

  1. Hosmackin

    Hosmackin Auditioning

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    Tom
    Hello all,

    I'm new to the forum as of 5min ago and haven't searched around much for the info I'm looking for, but thought it might be easier and quicker to get help to ask y'all directly:


    I have a Draper Framed projection screen up on the wall in my HT room, which I put up temporarily over a 500gallon aquarium since I don't use the aquarium anymore. Behind that wall is a small 6'x15 aquarium room. I am planning on removing the aquarium this week which will leave a large hole behind the screen.

    My question are:

    I would like to move all my speakers into the aquarium room out of sight behind the wall. Is it feasible and/or common for speakers to be mounted behind screens and what effect will this have on sound quality?

    Any factors or obstacles I need to consider attempting this project?

    What would be the best way to mount the speakers, should I build an enclosed box for them or just a base for them to rest on?

    Will there be any advantages or disadvantages to framing the wall back up behind the screen or should I just leave it open since the hole is already there?

    I also plan to move the stereo equipment into the aquarium room and cut out the wall next to the screen, and build some sort of box with a glass front. Any suggestions for that?

    The speakers I have are the Infinity Beta 50's, a Beta250 center, and an infinity sub.

    Any input is appreciated!

    Thanks
     
  2. Adam Gregorich

    Owner

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    Welcome to Home Theater Forum Tom! Sounds like that was some aquarium.

     



    This is exactly how they do it in the theaters. Its not as common in home theaters, but its the best thing to do if you can, and is how I did it in my theater room. Its rare because it eats a few feet of space, there usually are some audio and video trade-offs and it requires a perforated screen which can be expensive.

     

    Trade-offs:

    Perforated screens are expensive, and there are two basic types: perforated vinyl (Stewart and others) and woven material (Screen Research, SMX and others). The vinyl is more reflective as the holes are smaller, but it causes problems with the sound and requires an EQ. The woven material has very little (sometimes no) impact on sound, but since there are more and bigger holes, more light passes through sometimes requiring a brighter projector or more light control in the room.

     

     

    I would build an enclosed room/frame the back and side walls for them and put sound dampening material on the walls and ceiling.

     

     

    I personally wouldn't. You don't want a reflective surface right next to the screen. It could also cause some issues with audio as well. Even it you ditch the glass, I think you will find the equipment lights distracting. You could always cover them with a fabric covered door that allows IR commands through, but cuts down on the light from the display.
     
  3. Adam Gregorich

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    Here are some pics from mine. You can see more if you go to the link in my sig.



     



     



     



     



     



     

     

     

     

     

     
     
  4. Leo Kerr

    Leo Kerr Screenwriter

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    I've had a couple woven AT screens, and the size of the hole is not important to the viewer at a reasonable distance.
     

    Or even an unreasonable distance. I sit closer than I should to mine, and the only time I notice the "screen" is in bright flat areas (overexposed cloudy sky, concrete wall, etc,) in boring scenes.

     

    The important thing that Adam didn't mention about AT screens (in case you haven't caught the jargon, that's acoustically transparent,) is that light does pass through them. And behaves according to the laws of physics. Which means it can also go through the screen the other direction, too.

     

    The construction photos of Adam's shows an important feature: everything behind the screen is flat black. Except for the speaker-cones themselves. Does he see them? Care to comment, Adam?

     

    Light trapping is hard to be 100% successful with. I don't have the luxury of nothing behind the screen except speakers, because I'm in a multi-use zone, with all sorts of junk behind the roll-down screen. I've got a second roll-down screen behind mine with a synthetic black felt that helps cut down reflections.

     

    Good luck; speakers behind the screen is a bit tricky, but it works the best.

     

    Leo
     
  5. Adam Gregorich

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    I occasionally saw some reflections off of the front of the sides of the speakers (they are gloss black) so I got a large section of speaker grill cloth from Parts Express and attached it to the back of the screen frame. Since adding that I have seen no reflections. If you know where to look you will see the power light from one of my subs in a very dark scene. A piece of electrical tape over the LED will fix it, I just haven't done it yet. Because of the size of my screen I had to get a brighter projector and find that I end up replacing the bulb approx every 700 hours. I could also use the full bright setting on my PJ but that makes the fan audible. I also have to really control ambient light. My screen is an SMX which I would highly recommend if you were looking for an AT screen.
     
  6. Eric_L

    Eric_L Screenwriter

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    My two cents worth - after hurricane Charley put me out of my home for 14 months I was desperate to watch a movie. I was able to recover and move my projector into our temporary rental home, but I had no screen and not even a blank wall I could throw a picture onto. I was desperate. That was when my wife had the idea of using a king sized white sheet draped over the floor to ceiling entertainment center. Damn if it didn't work. It worked quite well in fact. Best of all - the speakers we had in the entertainment center played through the sheet beautifully. The sound actually came FROM the picture!
     

    If I were to use a fixed screen I would certainly consider trying a white sheet, or maybe gray. I would build a decent wood frame then stretch the sheet taunt and mount it tight. I would get a sheet with a decent thread count. I would starch the shit out of the sheet. Do that and I expect it would work quite well as your screen, especially in a room with controlled lighting. A sheet is quite sound transparent. Plus - if you try it are are not happy with the results - you are only out about $50. I'm sure you can find more expensive and 'expert approved' options, but I bet if you tried this and did a good job of mounting it - a very small number of people in this world would ever be able to notice a difference, and even fewer could tell you why.
     

    Simple. Cheap. Effective. Leave it to my wife to figure that one out!
     

    ps - only use NEW sheets... please.
     
  7. Leo Kerr

    Leo Kerr Screenwriter

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    sheets work quite well. My first DIY screen was.. not quite a sheet. Go to a fabric store, and look for the widest bolts of cotton fabric (preferred,) or some other light-weight, moderately tight weave, and no or low-sheen (avoid hot-spots.) I didn't starch it, I just stretched it on a light pipe frame (1/2" iron top and bottom, wrapped around 1/2" PVC vertical side pipes. As it relaxed, I could continue to re-stretch the screen by twisting a side-pipe. Worked surprisingly well!) I went to a motorized screen for convenience and size.. (I couldn't leave it out.)

     

    Leo
     

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