CurtPalme.com Home Theater Forum

patd · Joined: 17 Jul 2018 Posts: 3 Location: Sydney Australia

Hi all,

I've read through the tips and guides for NEC XG projectors and saw that it was recommended that they be placed about 7% closer than what the manual states.

Is this still recommended, and would the other measurements then have to be altered as well to reflect the given formula in the manual?

The screen is 155 inch 16:9
Ceiling mounted CRT

Also the calc. in the manual for distance E (distance between ceiling mounting surface and the projector feet for screens 150 inches or larger in diagonal) is a little confusing as I'm getting a negative result.

Is this distance critical?

If I ignore the E measurement and mount it hard up against the ceiling, the calculated distance between the projector feet and top of my screen will be 394mm.

wanderer · Joined: 11 Jan 2015 Posts: 63

155inch screen..... holy crap! I can't get over that size and I know it probably says that's OK in the manual, but that's going to be a pretty dim picture. But you might have a really high gain screen, so everything is OK again.

An XG expert will be by shortly enough I'm sure to comment on the mounting layout and distances for 16:9 . I just wanted to comment on the screen size!

patd · Joined: 17 Jul 2018 Posts: 3 Location: Sydney Australia

I was thinking the same thing with the screen size after ordering online. It hasn't been delivered yet, but had second thoughts about it last night. The room is quite large being 6x6 metres.

**kal** · Posted: Wed Jul 18, 2018 1:49 pm Post subject:

While following the manual for throw distance is always a good bet (and recommended for new users), to maximize tube life even further do the following steps:

1. Put the projector on the cart or simply leave it on the floor so that you can move it.
2. Display something that fills the screen entirely (like a grid test pattern).
3. Using only the green (middle) tube, look into the tube and increase the image width on the tube face until it is around 1/8" to 1/4" from the edge of the white phosphor. Under no circumstances should you allow the image to go off of the white phosphor surface!
4. Move the projector back and forth until the image fits your screen.

THAT is the correct throw distance for optimal phosphor usage, for any CRT projector.

It'll usually be 5-8% closer than what the manual tell you because the manual throw instructions are conservative since they make you install blindly without even looking in the tubes at all.

More: http://www.curtpalme.com/TubeCondition_PoorInstall.shtm

Is 155 inches (12.9 feet) diagonal of width? Either way it's too big. The picture will be dim. I'd recommend 8 feet wide max, maybe 9 feet wide if you want to push it. The bigger you go the less light output you get per square inch on the screen so the dimmer the image is. You can technically go with any size you want but if you want the image to have the right 'pop' you want to go smaller. Recommended light output by SMPTE standards is 14 ftL. You'll never get anywhere near that with a 155" screen.

Good luck!

Kal

HaydnG90 · Joined: 22 May 2006 Posts: 1335

Make sure you turn down the brightness/contrast before peering into the tubes.
As others have indicated at 155" you will not be happy with the image even in a completely light controlled room. You'll have to boost the output which will wear the tubes prematurely. I have a 100" diag Studiotek 130 screen and a calibrated Sony G90 in a light controlled dedicated HT and I sometimes want a brighter image.
To go that big you'll need to stack or go (cough) digital IMO

**Curt Palme** · Posted: Wed Jul 18, 2018 4:03 pm Post subject:

I have a 120" wide screen, only really do-able with stacking two 9" projector. Looks amazing, and in the 4 years I've had it, there's been no tube wear. With one projector though, I would have replaced the tubes by now. Doing it with an 8" set.. bad idea all around.

**kal** · Posted: Wed Jul 18, 2018 4:07 pm Post subject:

HaydnG90 brings up a good point: For CRT you want a screen gain of around 1.3 for best results, no hotspotting, no colourshifting. You can go higher for a brighter picture but you'll start to get issues.

Kal

HaydnG90 · Joined: 22 May 2006 Posts: 1335

The Dalite High Power, high gain screen was great except for the fact that the pj needs to be floor mounted. Very little hotspotting but with the benefits of 2.8 gain, decent colorimetry and no sparklies. I kept my old HP screen it was that good (don't think Dalite make this anymore).

patd · Joined: 17 Jul 2018 Posts: 3 Location: Sydney Australia

Thanks for the responses.

The big screen will be returned.

I have two XG110 projectors. One fully working with about 3500hrs, and the other with less hours has an issue with a card that makes the red tube look fuzzy or out of focus (I think) after an hour or so of use, is what I was told when I bought them about 3 yrs ago. I suppose I should have one complete CRT available for a little while with the spares on hand.

With previous comments about screen size, there is a used good quality screen available near me which is 8ft wide horizontally, 110inch diagonal 16:9.

Should I go smaller still?

wanderer · Joined: 11 Jan 2015 Posts: 63

I would be putting a coffee table or something similar in that room, putting the XG on top of that and projecting an image on the wall. I'd watch something for a while and take in the image, the size and brightness available at that size. Then move the table around to make it bigger, then smaller. View this from whatever seating distance you think you'll be using and it's going to give you a lot of good information about what works and what doesn't for you in that room.

For an XG and wanting to run the projector at moderate brightness and keep the tubes going for a long time you'd probably comfortably be in the 75-90" diagonal screen size range.

**kal** · Posted: Thu Jul 19, 2018 1:41 pm Post subject:

HaydnG90 · Joined: 22 May 2006 Posts: 1335

Typically it depends on your seating distance. Rough rule of thumb. Optimal seating distance 1.5x diagonal screen distance.