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Screen gain for JVC D-ILA projector
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wanderer



Joined: 11 Jan 2015
Posts: 43



PostLink    Posted: Sun Feb 24, 2019 2:50 am    Post subject: Reply with quote


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Your XG135 on that 92" screen was probably putting out 10ftl or so. Maybe more, maybe less. At about 10ftl your eyes were probably w-i-d-e open watching that XG image and just taking it all in easily; it wasn't super bright even when a largely white image, and sinking down to blacks was just effortless. And your eyes just soaked it all up nicely.

Throw a modern JVC on that 92" screen and holy crap. It's probably in the 40ftl range, or more, and it's also total light overload for your eyes which is heavily fatiguing. Reducing the light output of the projector using the internal controls and manual iris still wouldn't get it down to where you'd need it to be. The XD will help and cut the light in half, and that might get you back into a more comfortable viewing level for your eyes.

I've been down this road as at one point I had a Runco LED DLP test projecting onto a 100" 2.0 gain screen. Brightness was crazy and migraine inducing, so an XD filter went on and that got it back into the mid ~18ftl levels from memory. Dropping brightness further using the projector controls helped drop the light levels, but this does nothing for picture quality as these projectors weren't really designed to have the white level set at 50%. You can start to run into weird color issues as the internal CMS might not have been really calibrated for operating like that, nor does a digital behave like a CRT in respect to nicely linear behaving black>white output.

I'd view with the XD filter at a brightness level you like and see if you like the motion and image blur, color, 24P rendering, etc, etc, on the JVC. If you can live with that, then getting a bigger screen at lower gain would make sense.
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garyfritz



Joined: 08 Apr 2006
Posts: 10615
Location: Fort Collins, CO


PostLink    Posted: Sun Feb 24, 2019 4:50 pm    Post subject: Reply with quote

wanderer wrote:
Your XG135 on that 92" screen was probably putting out 10ftl or so. Maybe more, maybe less. At about 10ftl your eyes were probably w-i-d-e open watching that XG image and just taking it all in easily; it wasn't super bright even when a largely white image,

Especially since CRTs are current-limited, meaning they can only pump so much current through the tubes. Which means that if you try to display an all-white screen, it dims the max light level considerably. A small area of white with a black background will be MUCH brighter than the same small area on an all-white screen. Whereas the JVC is perfectly linear, regardless of how much of the screen is lit up. So watching something like Ice Age (lots of white on the screen) will be a LOT brighter with the JVC than with "equivalent" settings on the CRT.

cynix wrote:
so need to make some kind of cabinet to take the centre speaker with a shorter height flatscreen TV, a 32" or maybe a 40" with very small bezel might work and allow the centre speaker to sit about 6" lower.

I'm not trying to squeeze a flatscreen under there, but I have a very fancy stand for my center speaker: two stacked cinderblocks wrapped in black grille cloth. Very Happy Looks great and works a treat.
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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Sun Mar 10, 2019 11:48 am    Post subject: Reply with quote

Thanks again everyone for your comments.

I settled on a Tokina ND2 (0.3) filter, details on their site here:

http://www.tokinacinema.com/filters/pro_irnd_filters.html

Looks very factory fit :



the filter is the 105mm type (# PNDR-03105) and with a 103x3.5mm black o-ring around it it pushes into the ring at the front of the projector perfectly so no danger of it dropping out.

The image is now perfect, feels like watching film and not a big TV, just like my XG.

If anyone needs parts from an XG please let me know, probably the Moome HDMI card is the only part with any value now but thought I'd mention in case anyone needs something before it gets scrapped.
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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Mon Jul 08, 2019 9:34 am    Post subject: Reply with quote

I should update this with the latest development, someone may find it useful...

I was noticing an occasional, slight flicker on bright whites with the lamp iris down at the minimum setting (-14 or -15). With the iris set to -13 there was no flicker at all, it was only visible at iris -14 or -15.

There's a much bigger downwards jump in the brightness on that last click of the lamp iris (going from -13 to -14) than on any previous click, so I suspect they are actually reducing lamp voltage to an "even lower" lamp mode at that point, which would make the arc between the electrodes of the lamp more likely to jump randomly and induce flicker.

I'd read that some people were getting this flicker effect just in low lamp mode and the solution was to run high lamp mode for 10 hours or so, to "burn in" the lamp and help create consistency on where the arc was jumping between the electrodes in the lamp. I tried that but it didn't help, was still occasionally seeing flicker on bright whites at iris -14 or -15, but not at -13.

I found the image was too bright at iris -13 even with my ND2 filter so the solution was to replace the filter with the next one down, going to an ND4 filter (0.6, 2 stop), the Tokina PNDR-06105 and set the iris to -13. That removed the occasional flicker effect while still having the image as "dim" as I like. Smile

This is also useful for increasing brightness slightly in the future as the lamp dims, as the brightness jump of each click from -13 back to 0 is much more gradual than that big jump going from -14 to -13.

So if you feel your JVC DILA PJ is too bright and you want that cinema like CRT look, I'd recommend the Tokina PNDR-06105 and (manual) iris setting of no lower than -13.
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kal
Forum Administrator


Joined: 06 Mar 2006
Posts: 15794
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Mon Jul 08, 2019 1:06 pm    Post subject: Reply with quote

cynix wrote:
I'd read that some people were getting this flicker effect just in low lamp mode and the solution was to run high lamp mode for 10 hours or so, to "burn in" the lamp and help create consistency on where the arc was jumping between the electrodes in the lamp.

I'm on my third bulb now with my RS-56 and on my first bulb about half way through its life I started to get some occasional flicker when in low lamp mode so I shifted to high and left it there (it was time to do that anyway to maintain a ~14 ftL light output). So far my other 2 bulbs haven't done that so maybe it's something they fixed?

Kal

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