Accoustically Transparent Screens

Discussion in 'Projectors, Screens & Video Processors' started by meaux, Dec 17, 2002.

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  1. meaux

    meaux
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    Does anyone have any info on the effect accoustically transparent screens have on picture quality? It will be used with a Sony VPG-G90U projector. I have heard that brightness is affected. Can this be compensated for by increasing brightness from the CRT? Does increased brightness from the CRT decrease CRT life.

    In my room the bottom of the screen will only be approx 20"off the floor. If I don't use a transparent screen the center channel will be very low.(ie. under the screen) Will this position be detrimental to center channel info?
     
  2. Nick Beecham

    Nick Beecham
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    For me, the best compromise is to have 2 centre speakers, below and above the screen.
     
  3. Steve Bate

    Steve Bate
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    How about angling the centre speaker up towards the listening/watching position? I think B&W sell an angled stand for their HTM1/2 centres so it should be ok?

    To get the angle right you could always invest in a laser alignment tool to make sure it's firing at ear level!

    Steve
     
  4. Branxx

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    meaux,

    I have the same problem and I am looking for a microperforated screen. They are available but expensive.

    In a mean time I doubled my centre channel is behind the screen by stacking two speakers.
     
  5. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Steve: For Nicks's installation I did just that. Had a stand and brackets built specifically for his twin centre channels. Works much better than I was expecting....

    Gordon
     
  6. Alaric

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    Meaux,

    I have a worse problem, due to room limitations, my front speakers will also be behind the screen (as may the sub, but only 'cos its a handy place). I'm probably going to make the screen myself from fabric from Harkness Hall (one of the standard gain perfs). I'll have to make the suround from speaker cloth and i'll probably trim the frame (Aluminium box welded and braced, luckily i can get this made at work) in black velvet.

    Its gonna be quite costly (couple of hundered for the material alone) and complex, but I don't belive i have any other real choice - A 3m x 5m room, with the screen in the 3m. The speakers are also tall (1.5ish).

    I guess i'll need to EQ the front for the trebble loss, but i was looking at eq posibilities anyway once the room acoustics are finished.

    cya,
    Lee
     
  7. harry_thx

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    Hi,

    because we will move next year, I will get my home cinema cellar finally.
    Because I will do9 a complete new installation I would also try a transparent screen solution with on center speaker behind. Two problems. The one I have solved, it is the material. I have samples in hand of a really micro perforated screen material. Avaiable in 1.2G and 1.8g gain. the holes are so small and the distance so close, that they can´t be seen from 2m distance anymore. This screen material can be ordered in any size and costs about 65Euro for 1m². The small holes will keep the influences on the pisture quality in reasonable limits.

    But, and this is problem No.2 it is not easy to place a Speaker behind a screen ( no matter what hole size ever) without any loss in frequency. Unfortunately the high frequencies which are most important for pointing out the location ( sorry for my english, but I hope it will be understood), so associating the voices to the actors.
    This can be compensated by using a pre amp with possibility of frequency equilizing for single channels. Second solution is an external parametric equlizer. And the last chance, and this is what I will do, is adjusting the speakers yield ( is it the correct word?). Therefore you need something to measure out the frequencies of the complete installation and after that you have to recalculate the yield and adjust it by changing coils or else. Because I don´t have much experience with that, the speaker manufacturer will gett the frequency diagramm and will tell me what to do.

    But also some other ponits are important. You must have at least a distance between speaker front and Screen surface of about 30-50cm to avoide bad reflexions. Additional to that, you have to isolate the back wall accoustically to avoid reflections between Back wall and Screen.

    So, many thing to take care of, but I think it will be worth it.

    Best regards

    Harry
     
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