Question 155" screen and centre speaker location

Discussion in 'Home Cinema Buying & Building' started by tiff_lee, Jul 15, 2015.

  1. tiff_lee

    tiff_lee
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    Hi all,

    i'm just sizing up the custom size projector screen in my front room and was just wondering is my centre speaker being sat underneath such a large screen (155") going to cause any distractions? by that I mean the direction of the audio if you get me, or would such an issue be mitigated against by using a quality speaker (I currently have a Mission 75c which will need to be replaced....).
     
  2. KelvinS1965

    KelvinS1965
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    It'll probably end up too close the floor and won't sound great there, even if you 'aim' it towards your ears it is likely to sound boomy due to the proximity to the floor. To give you a bit of background: I used to have my PMC TB2+ centre about 9" up from the floor on a wall mount and it never sounded great and room eq didn't help either. I tried it raised up on a temporary stand and it sounded so much better I realised what I was missing. However this put it in the way of my TV (though below my projector screen). The solution was to replace my LCR speakers with on wall MK Sound MP150 speakers (they are quite thin, but very good quality) and put them all in line about 18" above the floor (my TV is on a lift so that it covers the centre when not in use). Even there I think there is room for improvement, so I'm planning on an Acoustically transparent screen early next year so I can move the LCR higher up so that they are in line with my ears.

    What projector are you planning for such a big screen as you'll need a lot of lumens to properly light that size up (ignore the manufacturer's claims wrt lumens too, you need to ask on the appropriate owners forum what the real world lumens output is).
     
  3. tiff_lee

    tiff_lee
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    Fair one I never really though about the lumens when seeing how big a screen I could fit! The projector is a JVC HD 750.

    As it stands my centre would be 9" off the floor as well, hhmm I do prefer the idea of the speaker being higher up in the centre. I just priced up new screen material and there is quite a premium attached to the "acoustically transparent" material.
     
  4. KelvinS1965

    KelvinS1965
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    Not wanting to wet your bonfire, but a HD750 won't light up a 150" screen very well I'm afraid. I used to own a HD350 which is similar in terms of light output and mine struggled to light up 128" with 1.5 gain. A bigger screen with less gain (even more so if AT) is going to look very dull.

    TBH unless you're going to sit a very long way back, you might be better off looking at a more realistic size like 106" diagonal. You won't need so much zoom in the projector (so the image will tend to look sharper), it will be much brighter (and you can then tone it down a bit with the HD750 aperture control) and you would be able to raise the centre speaker higher off the floor too as the screen won't be so tall. Another added benefit is that the side walls will be further away from the screen so you will get less washout of the image (less critical if you plan on covering the side walls with black material/paint, but not many do).
     
  5. Joe Fernand

    Joe Fernand
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    Room - dedicated Theatre or multi-purpose?

    Screen - ideally you would go with a fixed screen and use an AT surface, there are low cost DIY options.

    Lumens - does sound a bit big for the JVC, what does your seating layout look like?

    Format - are you going 16:9 or 2.35:1.

    Joe
     
  6. tiff_lee

    tiff_lee
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    Ah bugger, to be honest i'd rather just go and buy a new projector then reduce the screen size that much as it would just defeat the purpose of the room.

    I was going to make a fixed screen using material from carl's place (was looking at flexiwhite), format would be 16:9. Seating layout I hadn't considered too much apart from a seat plonked in the centre towards the rear.

    The room is dedicated for theatre use, walls will be black and no ambient light during playback.
     
    Last edited: Jul 16, 2015
  7. tiff_lee

    tiff_lee
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    Ok so just rigged up the oppo and projector on the floor and projected onto the wall (cladding painted white) so not the best surface.

    These are static photos but they look fine to me, perhaps i'm doing the wrong kind of test?

    Brightness at 0 and lens aperture to -8

    [​IMG]
    [​IMG]

    Aperture 0 and brightness at 50 (max)

    [​IMG]
    [​IMG]
     
  8. Joe Fernand

    Joe Fernand
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    Projector - ideally you'd hook up a video source, run a basic calibration and then watch a few movie scenes (a mix of dark and light scenes) - that will let you know if the projector is going to work for you on the screen.

    DIY AT will keep the budget under control and allow you to position the speakers in the ideal positions.

    Joe
     
  9. tiff_lee

    tiff_lee
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    Thanks Joe I think ill put a post in the projector section as it would be more appropriate seeing that my query seems to have moved on from what it started as.

    Could you just clarify what "AT" means when referring to a DIY screen please.
     
  10. Joe Fernand

    Joe Fernand
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    AT - Acoustically Transparent.

    Projector - reset it to factory defaults, stick it in 'Movie' mode and view a mix of scenes, how does the image look when viewing dark sciences?

    Joe
     
  11. KelvinS1965

    KelvinS1965
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    Just come back to this thread and wanted to make an observation: You don't turn up the 'brightness' control to increase the picture brightness. I know it seems an odd thing to say, but the 'brightness' really just sets the black level, so you adjust it so that you can see video level 17, but 16 and below appear as black...then leave it alone. Raising it up as you did in one of your pictures just turns black to grey and raises black level, making the image look washed out as you lowest picture demonstrates.

    With the JVC once you've set the brightness control (most likely '0' will be correct unless something in your video chain is messing with the levels) and also contrast (similar control but it sets the white clipping level), then you just use the aperture to adjust the 'brightness' (reflectance) of the image to suit the screen size and your taste.

    Not sure if you made a new thread in the projectors section now though...
     
  12. tiff_lee

    tiff_lee
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    Sorry guys been real busy and haven't moved on much with this.

    Joe, I put Aliens on which as i'm sure you know is quite a dark movie and it looked great to me.

    Hi Kelvin i'm glad you made that comment about the brightness, the image with it turned all the way up was me trying to get my head around what you meant when you was saying about the light output from the projector but i'm glad you clarified that for me thanks.

    Anyways as I said above I watched Aliens and a few other movies scenes and it all looked pretty good just going onto my wall although I do now have a complex about the speaker being too low, i'm not sure if it is really a problem for me or i'm concentrating on it after talking about it on here!

    So while i'm happy with the screen size i'm going to look a little more into speaker setups behind screens, give me an idea of what i'm letting my wallet in for etc
     
    Last edited: Jul 25, 2015
  13. tiff_lee

    tiff_lee
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    Ok i'm interested......

    bit browsing online for some speakers over here in Aus and those M&K 150 (inwall version) come in at about £750 at the current exchange rate

    MK 2 x 5 1/4 inch In-Wall Flushmount Speaker (IW-150) - Aussie Hi Fi

    So i'm thinking build a stud wall deep enough to mount the speakers then mount a AT screen onto the stud wall.
     
  14. Joe Fernand

    Joe Fernand
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  15. tiff_lee

    tiff_lee
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    Cheers Joe I had never heard of them but see they are based here in Oz. There is a platinum demo setup at a Hifi retailer about 30 mins from me so will be dropping by there and check their gear out.

    Thanks for the heads up.
     
  16. KelvinS1965

    KelvinS1965
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    Sounds like a great plan. That's a good price too as they work out around £1,000 over here. Supposed to be very similar to my on wall models (mine have a newer tweeter, but otherwise the same), you will need a decent sub(s) to back them up of course, but I'd assume you know that already.
     
  17. tiff_lee

    tiff_lee
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    I have 2 x PB12-Plus/2, I most definitely have that covered!
     
  18. KelvinS1965

    KelvinS1965
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    They'll do...


    ...for now. :devil:

    (I've 2 x 15" sealed subs at the moment, adding another 2 next year).
     

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