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NEC 6pg & HCPC settings

Discussion in 'Projectors, Screens & Video Processors' started by henry1234, Feb 15, 2003.

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  1. henry1234

    henry1234
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    I've been away busy building a P.C and now it's ready and finished I can hook it up to the pj.

    Over on the AVS forum there is some information on Powerstrip settings but I think these are optimised for NTSC dvds.

    To be honest I watch about 2 or 3 rental PAL DVD's a week and would like to optimize my set up for those.

    So I am assuming I want 50hz instead of 48hz or 72hz for ntsc.

    Can anybody provide their Powerstrip timing settings they have optimised for PAL inc porch, sync width etc)

    I assume I want 1024x576p 50hz for PAL
    or 720x576.

    I posted this on crt rather than hcpc forum becuase I need an answer closely related to an NEC 6 or 9pg or CRT projector rather than LCD or Plasma.
     
  2. Gordon @ Convergent AV

    Gordon @ Convergent AV
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  3. henry1234

    henry1234
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    Hello Gordon,

    Thanks for replying. I have a 4:3 screen but blank it top and bottom so I use 16:9 area.
     
  4. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    OK, more needed.

    Do you want the desktop to be 4:3 or are you using a crushed vertical height memory bank and always a 16:9 strip within your 4:3 screen.

    I ask for this reason.

    The projector works by drawing a dot across the face of the tubes. The size and shape of this dot is set by the EMF focus and astigmatism of the projector. With a 4:3 shaped screen you have a bigger area to draw your dot across.

    You want a resolution where each line drawn abuts the next with no overlapping or gap. This gives max resolution and light output. You can see with a 4:3 screen you can draw more lines than you can with a 16:9 screen.

    I'd guess around 600P-720P would be right with a NEC6/9 and a 16:9 screen. 720-960 with a 4:3 screen. I'd use 720 horizontal res....ie 720x600, 720x720 all at 50Hz. Hope this is some use.

    Gordon
     
  5. henry1234

    henry1234
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    I am free to choose at the moment I want to use whichever gives the best results.

    From what I can work out from your info are your saying it shouldn't matter becuase at the end of the day the scan lines will be in the same place after set up? a non squeezed 4:3 image at 960p or a vertically squeezed 16:9 image at 720p?

    Will there be a bandwidth issue using a 4:3 960p image?

    Can you explain to me why I would think I need to use a 16:9 multiple of the vertical resolution to calculate the horizontal resolution?

    Have I got the wrong end of the stick about hor resolution?

    Sorry for all the questions, this is one topic I'm finding difficult.
     
  6. MarkL

    MarkL
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    ditto Henry! - I'm setting up my 9PG and am struggling with this resolution thing.

    What is wrong with setting the HTPC to match the PJ factory spec of 1280 x 1024 ?(for a 4 x 3 image) The PJ alters the aspect (correctly)on it's own depending on the film I'm watching( I have no idea how it does this!).

    I run it at 75Hz on the basis that there maybe less flicker at this frequency. Is this true?

    Also have a problem with the image being too small on the phosphur even with the amplitude at 100%(still about 1/2" from the edges of the tube on both sides)

    Any advice would be much appreciated

    many thanks

    Mark
     
  7. henry1234

    henry1234
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    MarkL,

    I think the PG9 will scan at 1280X1024 @ 75hz but its at the upper limit of the horizontal scan rate and way way above the bandwidth of the projector.

    When you run at this resolution from your HTPC it will be the software DVD player that is setting the correct aspect ratio for the film and simply displaying the film material within the 1280x1024 display. See if you can turn the aspect ration control off, then notice if the display is tall and elongated. If your running a 4:3 desktop then you will want to put the aspect ration back on.

    There will technically be less flicker at 75HZ than 50HZ. But, on film based material (DVD's) you may not notice any difference depending on your set up (wall colour, material, screen size, individual tolerance to 50HZ). I think most people would notice the difference in flicker when viewing PC material.

    The higher resolutions and scan rates you run the smaller the image within the rastor. (I don't know why).For example, if you feed 800X600 @ 60HZ you will easily fill the rastor.

    I had always intended to use as high a resolution as I could get away with, but this may not be the best way to view DVD's. The only way is to actually try all the different resolutions and refresh rates and see which you like best.

    At the moment I use:

    720X480@72hz ntsc
    720x576@50hz pal
    1024X768@60hz for pc mode

    I turn off the aspect ratio control, then squash the vertical amp a little and increase the horizontal amp using the PJ. I set the amp back to 0% for PC mode. I use a 4:3 electric screen and blank top and bottom.

    Close to the screen you can see all the pixels from the DVD, but I sit at a distance of 1.75 X the width of the image. At this distance the image looks sharp.

    I may increase the rez as the PJ gets more dialed in. I have yet to do the Holy Focus thing, properly set up my P.C, get a decent cable and colour balance and many other things.

    To be honest I find it hard to believe that 720X576 can look so good. I could not understand why on earth people used these resolutions when the specs say the PJ is capable of so much more, but if you get your seating distance from the screen right this resolution can look great.

    I've yet to try Gordon's recommendation of 720X600 and 720X720, but these are on the cards. I think once I get optical and electric focus fully dialed in I may want to go up a bit to 600 or 720 as I guess otherwise the scan lines might get a little more noticeable.

    My next test is 720X720 for NTSC.

    Forgot to add;

    You must use Powerstrip advanced timming to increase the image size within the rastor, remember to lock scan frequency.

    And I assume you know not to get the active image too close to the phosphor edge about 5-6mm may be a guide to the closet. Too close and you mess up edge focus, convergence and risk overheating the tubes.

    You may want to look into colour balance, at default (50%) for RGB white and black my PG6 is way off.
     
  8. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Henry123 has got is sussed. You don't want or need to use such high resolutions.

    The reason less raster is used at higher resolutions is because the thing is because of the limited capabilities of the projector to draw the lines full width and height. Remember it has to draw dots and lines much faster to do more lines in same area at higher refresh. To all ow it to achieve showing such an inmput sihnal it just makes the area it has to draw on smaller....... It will result in faster wear and less stable convergence.

    I'd stick with 50Hz refresh for PAL and 60 or 72 for NTSC.

    I think 720lines on a vertical crushed anamorphic image is going to be close to ideal with one of these.

    Gordon
     
  9. MarkL

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    Many thanks guys - excellent answer! At last some things are starting to make sense. Much appreciated.

    Can you just clarify the following for me please:

    How do I turn off the aspect control ratio?

    What adjustments do I make to the advanced timing in powerstrip?( for viewing PAL DVD's @ 50 Hz) Does this only apply if the image isn't big enough in the rastor?

    Does 720 x720 produce a square image which you then squash with the vertical amplitude? Or does it simply show the limit of my knowledge???(I suspect the latter!)

    Mark
     
  10. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    I do not know how your dvd player software works so can't answer 1

    I'd ask the powerstrip questions in the HTPC forum where someone is bound ot give you detailed instructions. I can;t remember off top of my head right now.

    3: You use the geometric controls on the projector to create a geometrically correct image on the screen. This has to be done regardless of the pixel count resolution the PC is set to output. You need, ideally, a geometric test pattern disc to do this. Your PJ will load different memory banks dependant on resoutions and scan rates.

    My advice would be that once you have a resolution you are happy with you go in and delete all other blocks.

    Gordon
     
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