CurtPalme.com Home Theater Forum

yonexsp · Joined: 25 Apr 2006 Posts: 311

As Per Marks suggestion on another thread, I am starting this thread to get someone to try a simple idea.

Put Black felt/velvet masking directly onto the Glass Face of a Tube , actually the glass in front of the face (NON-LC PJ) to make a 16x9 letterbox to help absorb light spill

Kinda like the masking they use on cameras. The idea being that the some light will be absorbed by the material so cutting down on spill. This would only work it seems to me (well anyway) on a NON-LC PJ, as they have Flat glass in the front.

Has anyone tried this yet? Or willing to give it a go?

**Curt Palme** · Posted: Thu May 18, 2006 12:47 am Post subject:

I actually got a set in on trade where the previous HT owner had done exactly that. I took the masking off and didn't try it with and without, sorry, but the tweak is easy to go and makes sense to me.

Heywood Jablome · Joined: 12 Mar 2006 Posts: 1548

Facemasking is a penalty in anybody's game.

Very Happy

yonexsp · Joined: 25 Apr 2006 Posts: 311

What did he use as masking material Curt do you remember? Was it just black tape or Felt?

Anyone think there could be temperature issues?

Any guesses as to the improvement on CR?

Ridebreck · Posted: Thu May 18, 2006 4:23 am Post subject:

A really cheap option would be to buy some large strips of adhesive-backed velcro. Cut the soft, fuzzy side to fit and stick it in place. Of course, who knows what the adhesive would do to the glass on the tube face? Proceed with caution....

jask · Joined: 17 Mar 2006 Posts: 10187 Location: kamloops BC

I know!
I use about 500Meters a year at work so my guess is that unless the adhesive is fresh (yes it gets stale) it will not stay bonded for longer than a couple months - with repeated warming cycles the adhesive "dries" out and after prolonged uv exposure it will actually turn into a powder you can scrape off with your fingernail. if it is not dried out the adhesive can be removed with a little laquer thinner on a cloth, or some nailpolish remover (acetone)

the other thing that may work is the peel and stick vinyl that sign shops use for outdoor signs- fully opaque,thin, and tough and if you have a sign shop nearby they probably have some scraps

Mark_A_W · Posted: Thu May 18, 2006 4:45 am Post subject:

Umm, I don't think the glass will disolve...

Heat could be a minor issue, but it wouldn't stop me doing it if my lenses were off (but it's LC time for me Smile

)

WanMan · Joined: 19 Mar 2006 Posts: 10270

What exactly are you guys trying to mask? On non-LC, the unmasked region will surely still scatter within the entire lens assy. Adding a mask to the glass tube face seems like a good way to thermally insulate, but isn't that a serious danger?

yonexsp · Joined: 25 Apr 2006 Posts: 311

Yes Wan you are right, but some of that light should be absorbed by the masking (hopefully). So hopefully the should be less scattered light with the masking than without. I have no idea if it would make that much differnce, but it could be worth a try.

Ridebreck · Posted: Thu May 18, 2006 1:33 pm Post subject:

emdawgz1 · Joined: 14 Mar 2006 Posts: 7949

OK, ill ask...

Why mask on the tubeface ? If your raster is set properly what is the avantage of masking???

**kal** · Posted: Thu May 18, 2006 2:08 pm Post subject:

It does help a bit, but you have to be careful not to scratch anything. I'd also leave a tiny sliver of tube face clear at the very edge between the tube edge and the phosphor edge just so that I could see if ever the image expanded too much and came too close (or over) the phosphor edge.

I think Guy Kuo was one of the first people to do this...

Kal

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

danOO00 · Joined: 22 May 2007 Posts: 70 Location: Putnam County, NY

I spent last evening applying a black felt mask to the tube faces of my 9PGX, and the result is not subtle at all. I didn't take contrast ratio readings with the spyder/HCFR before and after, but I definitely notice a substantial increase in contrast by eye. I was also able to reduce the master PJ brightness by around 5 clicks, and still have decent shadow detail and near perfect FTB. (Using RTC2200) I need to see an LC machine to compare first hand (the first and only CRT I have seen is this one purchased from Curt), but I am very happy with the outcome.

I did this by applying some self-adhesive black felt to all the tube glass without active image - right up to the edge of the image on the tube face, and the lens mount at the outside edge. It took me a couple hours to do precisely including lens removal, re-convergence, etc., but I am very happy with the final result. Contrast is increased, and haloing is significantly reduced as well (used to be very evident on mouse pointers and theatertek screen saver logo, now not nearly as much).

I bought the felt from McMaster Carr http://www.mcmaster.com/ part #88015K2 for $10 with shipping. One foot was enough for about 10 projectors I would guess.

Not a problem with seeing if the active image is going too close to the tube edge with the masking applied either. With the lenses installed you can see underneath the masking pretty easily -due to the thickness of the tube face glass you get a nice view underneath/beyond the masking.

This mod, and the addition of black felt panels on the ceiling above the screen, and dark carpet below makes me very happy with the final CR and overall image quality!

Thumbs Up

Do it!

Dan

Chuchuf · Joined: 11 Mar 2006 Posts: 548

NEC did something similar on their XG LC tubes where they had some black material on the top and bottom of the CElement.

Terry

larryk · Joined: 23 Aug 2007 Posts: 106 Location: Edmonton Alberta

I remember someone suggesting the there is not very much heat to worry about on the glass face. I can't remember which thread but he or someone else also commented that they had good and quite noticable results with covering the tube face. What about the space between the now covered tube face and the lens. I would think that reflected light could still bounce around and find itself outside the front of the lens as well. Would it make sense to use muliple layers of the felt material so as to gently compress against the lens glass? That would seal that area completely. Or a different peice of tape to cover the lens? I would expect the you would have to experimemt because the felt would have to be tapered back in an arc until it is not interfering with the image?