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stacking 2 projectors

Discussion in 'Projectors, Screens & Video Processors' started by Cam, Jun 1, 2002.

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  1. Cam

    Cam
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    What screen size could be used by stacking by 2 Barco 1209's together? Presently I am using a 96" wide DaLite CinemaVision but have the chance of a 146" wide 1.85/1 Fixed Stewart Studiotek. I read on the AVS forum that the maximum screen for a 9inch CRT is 110" diag for best results. What other equipment would be required (apart from a second 1209) to stack them and would it make for problems that one projector has 620hrs from new and the other (not yet purchased) has just over 2000hrs?
    Info on best best configurations also wanted..eg, side by side,one on top of the other etc...

    Any advice gratefully accepted!

    Cam
     
  2. Roland @ B4

    Roland @ B4
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    I've done it a few times and the results are stunning.

    One or preferabley both projectors must have convergence on green. All tubes have to be the same age and same type you can't just buy another projector and hope to get the right sort of colour balance. but appart from that its pretty simple to do.;)

    One of the green's is used as the reference then converge the red and blue as normal. you then allign the green of the second machine to the red of the first. then the dilema starts which do you allign the 2nd red and blue to first projector or the second. (my feeling is that everything should be alligned to just one projector). (expect it to stay fully in convergence only after they have been on for about an hour.)

    Position of the projector depends on your room the best is to vertically stack them but not all installtions allow this. so side by side is the most common. (You can't do one on the floor one on the ceiling it won't stay converged)
    Sometimes it is worth changing the position of the Red and the blue CRT's on one of the projectors. That way you don't end up with so much colour shift.

    Your 146" screen should be possible and maintain acceptable light output. but bigger doesn't always meen better.

    You'll need a pretty good distribution amplifier to split the signal.

    Expect the resoloution to drop one notch as you'll be looking at 6 images instaed of 3.

    Richard Ansell from Snell and Willcox and I first met doing a double stack 1209 only to be told after we had set it up that we only had half an hour before we would have to de rig whilst a screening when on. That would give us about and hour afterwards to put it all back and get it perfect. (Which we did, just). I'm sure one of the Magzines did an article on it.

    Are you seriously considering this?
     
  3. Cam

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    I thought I had read somewhere that the projectors had to have the same hours on the tubes. The 1209 I have been offered has
    2074 hrs on the clock (on original tubes) and the one I already have has 620 (original tubes again) so they wouldn't be suitable for stacking. Thats a shame!
    The reason I had thought of going the 2 projector route was threefold - 1, the machine is at a great price, 2, I want the biggest picture I can get and 3, I saw a twin stack set up in the US (pair of BR12's I think it was) and the PQ was the best I have ever seen!
    I am buying the second 1209 anyway as its at a price to good to miss...but not low enough to warrant a proposal...hehe

    Thanks for all the info Roland
    Cam
     
  4. uncle eric

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    Cam,
    All things being equal, (and they never are in the CRT world) same hours and same age is more or less on the right track.

    I think what Roland is getting at is that the phosphor wear difference must be similar. If the tubes on projector A are considerably more worn than projector B, the beam spot sizes will be dissimilar thus making perfect alignment difficult and slightly inaccurate.

    If you want to go for this, I would suggest that a good starting point is to have new tubes all round in both projectors. This would give you a good starting block and providing the brightness and contrast on both projectors are kept to similar levels, wear will also be similar, therefore alignment will be pretty good throughout the systems operating life.

    Roland has the highest level of Barco expertise, so if anyone can, Rolond can.

    Eric
     
  5. Roland @ B4

    Roland @ B4
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    Run time on CRT projectors is almost irelevant it gives no indication of the wear.
     
  6. Chip

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    Unless its tube run times of course.
    I saw a stacked set up once and have some comments. Most well set up CRT's have an acceptable image until fully warmed up after which they reach optimum. When a well set up STACKED PAIR warms up it looks great. What I witnessed was that until then, things looked a little strange.
    All warm ups are not equal and due to the differences with these warm ups the image was awfull for around 20 minutes or so.
    I'm no expert but just my opinion,

    Chip
     
  7. Roland @ B4

    Roland @ B4
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    No. The run time either on the tubes projector or anywhere else you want to count it, is not an indication of the life left or used on a CRT. The phosphor on a CRT projector can be ruined in less than day. I've seen it done too many times.
     
  8. Chip

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    Really:eek:

    Chip
     
  9. Cam

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    The tubes on my 1209 are absolutely pristine with under 350 hrs run (250 ish were in standby) and the second 1209 I have been offered is supposed to have done less then 1000 hrs run time.
    The same guy I bought my existing 1209 is selling the second one and when I spoke to him this afternoon he informed me that he also has an excellent 812 that has 9000 hrs on the chassis and was retubed less than 1000 hrs ago. Would I be better going for the 12" model than stacking 2 1209's? The 812 has HD 219 lenses and looking at the Barco lens program I think these would be suitable for my purpose. The 812 is a fair bit more money than the second 1209 but if I sold on my existing machine that would cover it and the new screen. I have to make my mind up by tomorrow evening as I am off to Sweden Wednesday night to see the guy, the machines are from the headquarters of a car manufacturer and I don't want to miss out.
    Decisions, Decisions!
    Cam
     
  10. Gordon @ Convergent AV

    Gordon @ Convergent AV
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