Projectors

Discussion in 'Archived Threads 2001-2004' started by Nathan Friedman, Jul 8, 2002.

  1. Nathan Friedman

    Nathan Friedman Auditioning

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    Hey guys my dad wants to build a hometheater system when we get the basement finished. He was wondering if you could place a center speaker behind a projector screen.(Acoustically Transparent) Would it effect the sound in anyway? Or is it better to put it on top of the screen?

    Room Size 40' x 12' x 8'

    Would you guys recommend any certain projectors and screens?
     
  2. Neil Joseph

    Neil Joseph Lead Actor

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    Neil Joseph
    What is your father's budget? That more than anything will determine the kind of projector and screen he should look at.

    Perforated screens are available but I understand that they cost more (not sure how much) and that sound quality is somewhat different as compared to a regular screen. Someone else can chime in here with specifics about these perf screens.
     
  3. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    Unfortunately, there really is no standard with manufacturers, so it's hard to make a blanket statement about how micro perforations will affect your sound. To answer in a very basic way, yes, all screens, no matter how perforated, will affect the sound.
    Stewart gives you the frequency response graph of how their THX certified microperforated screens perform:
    [​IMG]
    MicroPerf Information from Stewart Film Screens
    They are reputed to be one of the best.
     
  4. Greg Risley

    Greg Risley Second Unit

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    I have also read that if you use a a fixed pixel projector (dlp,lcd) with a microperf screen that it can hurt the picture quality by over stating the pixel structure. Giving a a large screen door effect that is not uniform so it stands out even more. I have never seen this but it is out there as a possiblity. You might want to check over at the AVSforum.com
    Greg
     
  5. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    Actually, with something like the Stewart, you get 30k holes per square foot of material, with each hole covering only .02 of an inch. The only effect visually is a slightly lower gain.
    Now if you try to use something like the screens found in your local movie theater, with enormous holes, we're talking a whole different problem... [​IMG]
     
  6. Dean McManis

    Dean McManis Agent

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    I have had two preforated screens DaLite audiovision, and my current perforated Stewart Grayhawk screen, both were the same 16:9 180" diag size.

    The Dalite was very inexpensive, and I found that the sound attentuation was minimal. The perforations were visible within 10 feet on a white lit screen.

    But I did notice an audio improvement with the Stewart Microperf screen. It has smaller perforations, and many more of them per inch, offset like breathing holes in a BandAid. The perforations are visible only on bright/white scenes when viewed from less than 8 feet away (which is pretty close).

    Stewart has an inline THX module to compensate for the upper frequency sound attenuation, but my ribbon speakers are fairly bright anyway, so I didn't use mine and it sounds great.

    The downsides are a 5%-10% brightness loss due to the holes, some high-end sound attenuation (as mentioned), the cost (several hundred $ more), and with some digital projectors and certain screen sizes, you can see a moire between the pixel gap and the perforations.

    You would want to try out your particular projector with the perforated screen that you like, at the screen size that you will be using before you buy it.
    Alternatively, you can defocus the lens slightly, or get a Cygnus Imaging IMX-VT Image Processor (lens) to minimize the moire effect.

    I don't have that moire problem, but I have a larger screen, and screen sizes that are larger or smaller than a specific range don't have this issue, and of course CRT FPTVs don't either.

    The plus side is that the sound comes from the screen, just like in a real theater. I have all three of my front speakers behind my screen, and it really makes an immersive difference having the sound and image line up so well on the screen.

    -Dean.
     

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