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Discussion Starter · #1 ·
I'm interested in the NEC pgs, esp since they are smallish and my ceiling is 8', but need some info from someone who's been there.


1. I know they're not the quietest pjs, but have you had luck with fan mods? How many fans ,how big are they, how accesible are they, and what did you do to succesfully quiet them?


2. Can the PGs resolve 720p in a 16x9 arrangement? Is there any special trick to squeeze the pic or is it simple?


Enough questions?

Seriously, thanks for any details on these critters!


Vince
 

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Discussion Starter · #3 ·
It's not really a necessity, but for HDTV I would assume it's the preferred resolution; or course please enlighten my ignorance if this is a wrong assumption... what do people run on CRT for HD? 1080i? I don't have HD sources yet but more and more are adding 720p outputs it seems. Maybe it's my 1031 but my beam size seems pretty fat and I am thinking that an EM machine with higher resolution will have more crispness. Hey, I had decided to hold out for the digitals to catch up to the 10000:1 range but that could take years :)
 

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I'm not sure as I have not tried it myself, and I am quite please with the way my HD STB puts out 1080i. I would first investigae what refresh rates you might be limited to in order to make use with whatever bandwidth you are limited to, and laos do a substantial amount of reading on PG setup to attain the sharpest focus in order to avoid overlapping scanlines.


Have you seen a PG in action, and if so which one(s)?
 

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First off, You want to use the native resolution transmitted by the povider.

1080I is the most common HD resolution supplied. The PG does 1080I great. For some reason they seem to struggle with 720P. In my case, resolutions above and below 720P work just fine. Go figure.


Chip
 

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Discussion Starter · #7 ·
From a spec standpoint, it seems like all the PGs can go 720p easily.


according to projector specs all the PG6 can do 1280x1024, and the PG9 can do 1600x1200, all with video bandwidth of 70Mhz or greater. According to this

Quote:
1080i HDTV has 1080 scan lines containing picture information (and 45 scan lines for retrace and synchroniziing for a total of 1125 scan lines). Horizontally there are 1920 visible pixels occupying the first 87.3% of the scan line and we must pretend that there are 140 similarly sized sync. pulses with 140 gaps in between, filling the rest of the scan line. (The total pixel count is 2200 per scan line.)

The scan rate is 30 (29.97) full video frames per second.

Multiply 1125 x 2200 x 30 per second and we get about 74 million pixels per second. Since one cycle consists of one black and one white pixel, the bandwidth needed to display the smallest picture details is 37 MHz.

Coincidentally, 720p also requires 37 MHz.. 720p has has 1280 visible pixels and room for 1650 total pixels per scan line. It has 720 visible and 750 total scan lines repainted approx. 60 times a second. 750 x 1650 x 60 is about 74 million black/white pixel pairs or about 37 million cycles per second.
the requirement for 1080i and 720p is technically the same. I had assumed that the PG was totally capable of 720p from an electronic standpoint, I was mostly inquiring about the reality of getting 720p in a 16x9 format without major scanline overlapping, etc., i.e. would the PG series truly resolve 720p @ 16x9 format???


Just to mention, I'm happy with HTPC so given powerstrip and a nice Radeon video card I think any quirks can be overcome if the pj is up to it in the first place.
 

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You are talking addressable resolutions, not well-defined (sharply display) resolutions. The problem is that they can display 720 lines progressively, but you will probably run into a condition of overlapping scanlines.


Displaying 720 lines is one thing, displaying 720 lines so they don't overlap is quite a different thing.
 

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I have 720P without overlap on a 6PG+ and a 9PG (just)

Re the noise, after cleaning mine are very quiet with the standard fans, most of the noise was due to dirt. After cutting away a few of the parts that were restricting airflow, they are very quiet indeed - well below the rated DB according to my soundmeter, and on my (high) ceiling can only be heard in a silent room if you listen for it. With lower DB fans and some cleaning and cutting I am sure they would be quiet enough.


Dunno if I would classify it as small, they look as big as a house to me, but I guess its all relative.
 

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dokwork, what refresh rate are you running your 6PG+ at when you are running 720P? I've compared 720P to 1080i on my GE Imager 601s (6PG/+?) and the scanlines start to overlap in 720P (but sharp as a knife in 1080i).
 

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What do you mean by "sharp as a knife" at 1080i? Just wondering since the scan lines are of course overlapping more.


I have ran my 6PG from 480P to 1080i and notice scanline overlap starting just above 720P, enough so that by 768P it is not worth it unless I want to double DVD res to 960P (some DVDs look better at that resolution).


I typically run 1280X720 @ 72Hz, though it is happy up to 75Hz.


It is currently setup for the following resolutions/refresh rates in both 4:3 and 16:9 aspect ratios:


480P @ 60, 72, 90, 120Hz

540P @ 60, 72Hz

600P @ 60, 72Hz

666P @ 60, 72Hz

720P @ 60, 72, 75Hz

768P @ 60, 72, 75Hz

960P @ 60Hz

1080i HDTV
 

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You see scanlines much easier at 1080i because the PJ just writes 540 lines at once. If you move vertically with your eyes with the right speed, the lines of the two offset half-pictures overlap and you see the dark lines between.

Try to see scanlines when a still picture is displayed and you try to look at one detail in the pic avoiding any eye movement.

Then watch a movie and look at the actors hands. The hands move vertically very often with the right speed to see the interlaced sharpness effect.

BTW:

If you wanna go for a PG, go for a PG+ because it has a sharper picture.

Roland
 

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There's a couple of very recent threads on 720p and Pg's - try the search function.


My 6pg xtra romps in 1280x720p at 75hz - although the bandwidth required is over spec - it is still sharp.
 

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The problem with PG's and 720P is not it's ability to resolve it. It has to do with internal test paterns/external signal matching. I can get a very sharp picture but, the geometry of the image is not even close to the internal test patterns. Do the search as recomended. Doug Baisey just discussed this.


Chip
 

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Quote:
Originally posted by Teran
What do you mean by "sharp as a knife" at 1080i? Just wondering since the scan lines are of course overlapping more.
Why on earth would I have a condition in which overlapping scanlines are more prominent with 1080i than with 720P. Using 1080i I am only projecting 540-lines at any given time and as such none of those 540 lines are overlapping.
Quote:
I have ran my 6PG from 480P to 1080i and notice scanline overlap starting just above 720P, enough so that by 768P it is not worth it unless I want to double DVD res to 960P (some DVDs look better at that resolution).


I typically run 1280X720 @ 72Hz, though it is happy up to 75Hz.


It is currently setup for the following resolutions/refresh rates in both 4:3 and 16:9 aspect ratios:


480P @ 60, 72, 90, 120Hz

540P @ 60, 72Hz

600P @ 60, 72Hz

666P @ 60, 72Hz

720P @ 60, 72, 75Hz

768P @ 60, 72, 75Hz

960P @ 60Hz

1080i HDTV
I am assuming one realizes that 1080i is syncing at the same rate as 540P, which is much lower than 720P and well within the bandwidth limitations of these units.
 

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Discussion Starter · #16 ·
Quote:
the geometry of the image is not even close to the internal test patterns
I always calibrate using the nokia test from the htpc. I am used to issues since my 1031 won't (for whatever reason) bring up the calibration screen. No big deal.


I did search but found alot of conflicting info, esp in the thread you mention. I wanted to hear from others who have it working.


Thanks for all the responses, and the pg+ advice. Much appreciated!


Vince
 

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Quote:
Originally posted by WanMan

Why on earth would I have a condition in which overlapping scanlines are more prominent with 1080i than with 720P. Using 1080i I am only projecting 540-lines at any given time and as such none of those 540 lines are overlapping.


I am assuming one realizes that 1080i is syncing at the same rate as 540P, which is much lower than 720P and well within the bandwidth limitations of these units.

They are the same as far as bandwidth and how many lines are drawn each scan, but aren't their output quite different, especially in the ability of the projector to resolve that resolution? 540P is drawing 540 lines where each line is 1/540th of the image height while 1080i is drawing what should be 540 lines where each is 1/1080th of the height. Right?
 

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dokworm,


What did you cut away on your pj to clear the fans ? My 6PGextra does make a LOT of noice, 70dBA according to specs !! I have no sound meter to check this, but the dB figure is probaly true. I wanted to take away the grills of the two bottom fans, but they can not be dismantled without removing tubes. Removing the tubes is something I will not even TRY. _Cutting_ away the grills should be possible, but maybe look a little akward. It would be good if the fans could be silenced by just clearing dirt and cutting away airflow restricting objects, maybe this would make a hushbox unnecessary.


Thanks, Thomas
 

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Azzad quietened his down - PM him for details, or perhaps he will pipe up.


I don't think removing the grills did anything.
 

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Todd, I'm having a little problem with "540P is drawing 540 lines where each line is 1/540th of the image height while 1080i is drawing what should be 540 lines where each is 1/1080th of the height."


While I get the analogy, there is a distinct difference between the total number of different lines that will be drawn, period. 540P will draw 540 lines total to produce a given picture, but 1080i will use 1080 lines to draw that picture.


This may be semantics, here, but this is how its interpreted to me. I'd much rather see a 1080-line image than a 540-line drawing. And while one is constrained within the limit of the number of lines totally drawn in 1/30 second results in 540P vs. 1080i, I would need to discern more quickly than every 30-milliseconds.
 
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