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Center speaker and screen with DLP

Discussion in 'Projectors, Screens & Video Processors' started by HouseofMu, Jan 23, 2002.

  1. HouseofMu

    HouseofMu
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    I've just read the latest HCC mag, an its article about their new HomeCinema installation.

    My question is about the decisions behind the choice of screen that is suitable for certain types of projectors.

    They state that the correct center speaker position is behind the screen, which I'm not doubting (even though I've seen many of the featured Home Installations done by professional companies even in this mag below the screen), which means an Acoustically Transparent Micro Perf screen should be used, but this rules out DLP as the perfs would cause a moiré effect.

    Does this problem apply to the newer TI HD-1 projectors, with their higher resolution? If this is the case does it mean a correctly positioned Center speaker can only be used with a CRT projector?

    When I (eventually) plumb for a projector, this creates two problems for me as I'll be integrating it into my living room:

    1) The missus will only allow a nice and small DLP box to be hung from the ceiling, to be fair a CRT would be impractical.

    2) My screen will be dropping down slightly infront of current tv, that has a decent sized B&W LCR6 center ontop of it, this means its positioning can only be behind the screen.

    Can anyone who has experience of this sort of arrangement give any extra info on what was said in the HCC mag?

    I was anticipating a 7ft screen from about 12f away, using a DLP pj (may be HD-1 or even HD-2).

    Thanks.

    n.
     
  2. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    This is one of those things where it's going to depend on the screen type and the projector. Don't know anyone who has tested an HD1 chipped DLP on acoustic material.

    The HT200 was launched at a cinema. There was no moire there. Of course, those were pretty BIG holes in that acoustic screen.

    I'd suggest asking the screen manufacturers. I've found Stewart to be most helpful and truthful in this regard. My other acoustic screen supplier was not quite as forthcoming.....

    Gordon
     
  3. Jeff

    Jeff
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    Without going as far as saying that HCC are talking out of their rear opening, I would suggest that positioning the centre speaker below the screen is perfectly acceptable. I would never use a perf screen.

    Jeff
     
  4. NickBull

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    To echo what Jeff has said, I use my centre speaker just below the screen, sit 12 feet from a 92inch diag. screen and the dialogue is locked perfectly to the screen.

    I'd say it's more important to have all your front tweeters at the same height to get a better surround effect.
     
  5. HouseofMu

    HouseofMu
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    Firstly, thanks for the quick responses.

    I'd like to keep the tv in the same position for everyday use (and consoles) so it to could also be used with the surround setup.

    Unfortunately, as the tv is 32" and the B&W center is of the large variety, you can imagine its quite a height. I was assuming I'd need a perf screen as I thought the drop from the ceiling would cover it. Can anyone tell me what the approx drop from the ceiling for a typical 7ft screen would be, that way I can re-measure to see if I could get it to stop just above the center speaker, which would of course get around needing a perf screen (and saving money no doubt)?

    I've checked out some installation photos on the Stewart site, they seem to have quite a large additional drop area above the screen, if this could be reduced to a minimum I might be able to achieve it. Although I'd imagine that the viewing angle would then be slightly upward, instead of straight on, does anybody else have that viewing angle?

    I had thought about moving all the kit out from under the tv into their own rack, then putting the center under the tv. This would allow me to drop the screen much lower (right infront of the tv with the mains would be far enough apart to be either side of the screen), but had dismissed this setup as I thought the center sound would then be firing at knee height. The additional 'correct position' comments in the HCC also gave me doubts, but do most of you have it 'below' too?

    Sorry to drag about this, but I now find myself constantly envisaging screen/speaker arrangements whenever I sit down to watch tv! Its taking over, but its something I'd like to get right when the time comes and I hoped you pj owners with may have had similar design headaches.

    Any more suggestions/experiences would be helpful.

    n.
     
  6. Roland @ B4

    Roland @ B4
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    First the obvious stuff
    A typical 7ft wide screen has 2inches if black boarders to take off each side. making the actual display 80" wide

    For a 16x9 screen the picture hight will be (80/16) x 9 = 45 inches
    and a 4x3 screen (80/4) x 3 = 60 inches

    then add your 4 inches of black.(2" top and bottom)

    Most 16x9 screens have a black top section which is variable in its drop. Typically this about 12" but can be made to order.

    Possitioning of the screen is down to personal choice and often will depand on the height of the room.

    I genrally recon that sitting on a sofa my eye is 3ft from the floor and that my eye should be 1/3rd of the way up the screen

    So if my maths is correct that puts the bottom of your screen 21" from the floor.

    1/3rd screen = 15"
    viewing possition = 36"
    36-15=21

    Be carefull ablout a perforated screen with any thing shiney (TV) behind it you may be able to see a reflection. My experience is that DLP projectors casue less morie than LCD but the effect is still there.
     
  7. Grubert

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    Stewart Screens tested the Sharp XVZ9000 with their microperf screen and concluded you get moiré if your screen width is LESS than 88 inches.
     
  8. HouseofMu

    HouseofMu
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    This additional information is beginning to make me re-think about the type of projector to get.

    If I was to go for a CRT, could anyone tell me a typical total ceilng drop , including its mouting bracket?

    I was aiming to save £9k for a new generation DLP unit, would that be enough for a CRT instead ?

    n.
     
  9. uncle eric

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    When using screen sizes of more than 100 inches wide, Cedia, amonst others, stipulate the use of perf screens. In fact, if identical towers are used, theres not much else that can be done.
    This they say, ties in the sound well in relation to the screen. True enough.
    The other point being that there is not really much room left below the screen with normal ceiling heights.
    On a nine foot screen for example, the screen hight would be 72".
    Once a few inches for drop and black border is added this can end up at nearly 7ft.
    Most ceiling heights these days are around 8ft. Unless you are a Pixie, your centre speaker will not end up at ear level.

    All this can be avoided of course by using slightly smaller screens (I use 87"x49") together with smaller speakers. I dont use towers.

    Apart from problems that perf screens have with single lense devices, there are other considerations.
    Loss of light for example is one. A conservative estimate for Micro perf light loss is around 10%.

    My main bug bear however is the phrase, "Acoustically transparent".
    This is impossible! The phrase implies that sound waves go right through, uneffected by whatever is in front of the sound source. Any obstacle no matter how thin or perforated has solid substance to it. This will in varying degrees effect and degrade the sound.
    Even speaker cloth does not fall into this 'transparent' catagory.
    For instance, Ken Kreisal of M&K recommends that speaker covers should be removed during serious listening.

    Perforations, or 'holes' in non marketing talk takes up X amount of space on a given screen area. The rest is taken up by the screen material itself. This is a fairly consistant obstacle. Ok, not a dense obstacle but something that I for one can do without.

    Anything placed in front of a sound transmission is an obstacle or barrier. Call it what you will, this or any other consistent material changes or distorts whatever is trying to fire through it.
    Equalization is the main weapon for problems arising from the above, but again, we are adding more artificiallity to the whole chain. Any 'fix' leads to more compromises and is ultimately not optimum for overall sound quality.

    Lastly, unless the wall behind the perf screen is matt black, varying degrees of light bounce back will occur.

    Eric
     
  10. HouseofMu

    HouseofMu
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    Roland @ B4,

    thanks for the sums, I'll be doing some measuring tonight.

    To everyone,
    I see s/h BarcoGraphics 808s are about £5900, what would be their direct competitors that I should be checking out, also how much would the extra kit such as Line Doubler/Quad processors push the price up?

    I original planned to spent 9k on a DLP, but was just wondering what that would get me in CRT kit?
    I realise I would have to set some of that aside for installation, if anyone has had this done for them, would you mind giving me a rough £ estimate (so I can re-budget)?

    Does a HTPC replace all these extra signal processors or work in conjunction with them?

    thanks.

    n.
     
  11. Roland @ B4

    Roland @ B4
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    The BG808s has three main Competitors

    Sony G70
    Electohome Marquee 8100
    NEC 9PG

    Barco still make the 808s (for simulation use)
    the others stopped making CRT's between 2-4 years ago.

    The Sony makes a racket I lost could of how many fans it has.
    The E'home has small foot print but is very tall.
    The NEC is a nice projector but a bit rare.

    By the sound of it you have not seen a Good CRT working. I would send Fulabeer a PM he's not too far away from you and his room is something else.

    Projectors can be had for cheaper but know what you are buying.
     
  12. NickBull

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    If you have room go for CRT. I have a Barco Graphics 808 run from a pc and it is stunning. I still think I have some improvement once I change the DVD software.

    Gordon is a good person to talk to about scalers I believe if the PC route isn't what you want, it is a bit of a faff!

    There's a few people who have recently got 808's on here. They'd all be happy to help.

    Nick
     
  13. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Can I just add that the NEC6/9's were replaced for the final 3-4 years of manufacture by the NEX XG series. These are probably more representative of the 808 series.

    XG's are even more rare in this country.

    Gordon
     
  14. HouseofMu

    HouseofMu
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    Thanks for the suggestions.

    I am moving house soon and if there's enough room to accommodate a CRT I'll definitely go-see some demos. I work in computing, so am not afraid to go for a HTPC set-up if this gives the best results. I take it there are preferred DVD drives, gfx cards and s/w that you use ?

    I re-measured my current lounge, and with the help of some better (lower/wider) under-tv cabinets (I followed an ad link to ARCA), I think I could get my AV equipment/consoles and center speaker in , which would eliminate the need for a perf screen.
    With the screen problem no-longer an issue my options are again open for pj choice, DLP with its compact ease of use/set-up or CRT (better performance/value) space permitting of course.

    Just a couple of last questions:

    Am I right in thinking Barco's Cine range are the replacments for the 700/800 CRT's?

    What ever happened to that 'all-in-one' wonder processing box somebody on the forum was making?

    Thank-you all for your input. By the time I'm ready to buy there might be another 'Event' I could attend to help decide? (especially if it were to have some HD1/2 DLP's to compare against too).

    cheers.

    n.
     
  15. rigman

    rigman
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    I have just bought a refurbished Barcographics 808s with brand new tubes and a Rock plus and including installation ceiling brackets and cables. The total price was less than your stated budget of 9k. It is running at 960p and looks stunning.

    You are correct in saying the cine series are the replacements for the 708/808.

    I think it was Jenz that was developing the all in one box and I have not heardany word on it for a while.

    In answer to your earlier question regarding HTPC, yes a PC can be used instead of a video processor but they are not that user friendly. I decided to just buy a Rock so my wife can use the cinema system when I am away as more or less all you have to do is switch it on. There is lots of info on HTPC on this and the avsforum if you wanted to check specs, software, tweaks etc

    I have a set of M&K S-150 speakers for the fronts and the top of my centre speaker sits within the bottom black border of my screen. It is about one foot below ear level. The speaker stands for these are adjustable and I have it firing upwards slightly. Could you put the LCR6 below your tv and use cones to tilt it upwards so it fires direct to your ear level?
     

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