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overly technical DLP thread

608 Views 11 Replies 8 Participants Last post by  doug_k
Still obsessing over the lack of brightness of the HLN507, I have these questions/ideas:

- When using a color wheel, the entire DLP shuts it's mirrors "off" while the edge "spoke" between colors sweeps across the light path. This is as much as 10% of the time. You'd think that it could keep those mirrors on for the pixels that are displaying very bright whites. Or do they already do this?

- What happens to the light that's reflected by micromirrors in the "off" state? Why isn't this light recaptured and fed back into the light path before the color wheel or prism? The light efficiency of a DLP rptv is around 10%, it just seems strange they're pursuing SCR when there's this more obvious cause of inefficiency.

Feel free to comment. I'd love to have some insider TI/Samsung/etc information about what they've tried, what they're tinkering with, what might make it to future products.
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lack of brightness of the HLN507
Seriously? I took delivery of my HLN507W yesterday. I'm amazed at how bright it is. FAR brighter than my 32" Panasonic CRT was. Perfectly viewable in a room with a LARGE picture window on a sunny day.

Feel free to comment. I'd love to have some insider TI/Samsung/etc information about what they've tried, what they're tinkering with, what might make it to future products.
Slim, meet nil. Nil, meet slim. Nice to meet you both.

I'm sure the easiest way to get more brightness, if they thought it necessary, would be with a brigher bulb.

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That's what lots of people say, but the peak whites/colors look muted to me (as opposed to 437 and 617).

Indeed- they ought to offer a brighter bulb for it...
Doug, check out the >$5000 RPTV forum. There is a lot there on DLP technology and such.

You might try some searching, but also asking your Qs there as I'll think it'll stimulate people to reproduce earlier comments.

The single-chip DLP is, indeed, light inefficient. But many people are pleased with the amount of light they do get. The Philips method of the rotating prism does seem quite a bit more light efficient as it doesn't waste much (if any).

But the need to reflect light away with the DMD yields wasting of light as well as no obvious practical way to leave the color wheel behind.
Rogo-- thanks, the discussions really are more detailed and technical over there. (you mean the >$5k front-projector forum, right?)
I am not surprised that you do not find DLP bright ehough, although most do. I did have some doubts myself and tried a "cheat" but for the most part I abandoned the project as it did not produce reference quality picture.

If you have a HTPC you could try to crank up contrast controls on your HTPC with offseting brightness adjustment (use something like AVIA or Digital Video Essentials for fine tuning). This will give you perceived increase in dynamics of the video signal and greater difference between blacks and peak whites, making the whites look "brighter". This happens at the expense of detail at the peak white range and bottom black range. While not anoying at the black level, this cheat is sometimes anoying at peak white. This cheat will not work with some material like Chicago that already has great dynamics and this "cheat" would render the movie practically unwatchable. A friend of mine (plasma guy) liked LOTR TT on my DLP with contrast up 20 points via HTPC.
Doug- I am having a hard time trying to figure out why you are unsatisfied with the light output. What was your previous TV that offered a higher output?

I spec these sets when having to compete with high ambient light levels. I suppose a plasma would seem brighter, but there is a big cost differential.
The brightness of whites can be cranked in the service menu with parameter Sub_Ct(DDP).
Doug, right the >$5K Front Projector, [sheepish :)].

I find the light output more wanting on the 50" than the 43" and more wanting still on the 61", despite the larger lamp wattage.

But, for me, at least part of that is in-store comparison. I think in my home, I could be satisfied with any of them.

Generally speaking, light output is not so much "cheatable". As correctly noted above, once you muck with settings you will crush highlight detail or lose shadow detail.

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I'm baffled as to how the 507 whites could be considered anything but very bright if the contrast is adjusted correctly. I think my 507 could be adjusted so bright that if someone walked between me and the TV, I could see their skeleton. :D

If the issue can not be solved in the user menu, then maybe it could be addressed in the service munu like Tom suggested.

Could be a problem with the set too.
"The mind of a child is....

Have you thought that maybe your bulb is bad or the set has something else wrong with it?

Go find and identical set somewhere and see if it's any brighter.

I don't own a DLP, actually-- I was so ready to buy one the day PC Richards got it in, but it looked like crap with LOTR and starship troopers (my 2 demo dvds). I'm still using a rotary dial color TV, and refuse to pay $3-5k for a TV and have to sacrifice any aspect of quality; the TV I paid $25 dollars for in college is brighter, is higher contrast and has better colors than I've ever seen on a DLP.

I haven't had any wayto tweak the "gamma curve" on the DLP like you guys are suggesting, although I've done it with Powerstrip and my own monitors and it does indeed crush the whites/blacks.

Every 507 i've ever seen in a store has had the contrast at 100%. There's a store around here that has two 50" models; I went into the SM and set one's lamp on the 120W mode, that was very nice, but over the last few months its brightness has gradually drooped to equal the non-tweaked one.
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