New AT Screen build - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 08-10-2017, 08:41 AM - Thread Starter
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New AT Screen build

My current screen is just plain wooden frame with Carl's Place 1.0 gain blackout and 3" black velvet tape border. It is a 16:9 at 185" diagonal or thereabouts. It has served me well during the years and has dazzled myself and my friends many times. It has survived the house full of kids... I have zero problems with it.

However, I recently acquired a Panamorph UH480 A-lens and I am looking to build a 2.35:1 or 2.40:1 screen. This one is going to be AT screen and thus I will utilize the newly available extra space on the sides to make it a bit bigger - about 222" diagonal. As a random thought I would like my screen to be a bit taller so it will probably be 2.35:1 .. but this is still in the air.

I have determined through experimenting the amount of curvature to eliminate the pincushion of the A-lens and it is about 2.5-3" raise on each side. Many thanks to the folks that posted how to determine curvature by moving forward a small portable screen on each side until the distance from bottom of image to floor is identical on the sides and center of the screen.

I researched for a while the different frame buildouts and I have decided to keep it really simple (lets see how that is going to go lol..). The frame will be build from 80/20 30-3030 30mm square t-slot profile with inside/ hidden 90 degree angle brackets at all corners and for the center supports. I have decided on 2 inside support columns/ beams as I dont want any metal in front of my center speaker. The 30-3030 also comes in black color, but I could not source it, so once assembled I will probably spray paint it black so it doesnt reflect through the AT fabric. Speaking of the fabric I have decided on the Seymore XD screen material. I just received the roll from the vendor and the fabric looks amazing. It will be secured to the frame with suitable wooden dowels wedged in the t-slots (thanks to the guy on the forum that gave me that idea in his build out post).

I wasnt sure yet how I will be bending the t-slot profiles, but I acquired three 6 meter long beams and they are far more flexible than I thought they will be. Initially I was thinking about bending them with a section bending machine, but looking at them I will probably just prop the two ends on wooden blocks and push gently down in the middle until I achieve correct curvature. We shall see how that goes lol.

The frame will be suspended from the ceiling with picture wire to give it some ability to be swayed/ moved for access to speakers behind it.

Once I receive the angle brackets I will begin with the buildout some time next week. I will post pictures and comments and suggestions are welcome. This will be a screen that I will build with materials I have no experience with, so it should be educational and interesting- hence me starting this thread.

For now- here is my current setup as a baseline.
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Last edited by partcrash; 08-10-2017 at 10:20 AM.
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post #2 of 9 Old 08-13-2017, 07:41 AM
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Ambitious.....but promising because others have tackled Curved Screen builds and come way with some very noticeably excellent results.

The size your attempting, along with the use of a Panamorph Lens does (...or can...) require a curvature, IF the projector does not have an integrated Stretching Mode. If it does...the amount / degree of needed curve is drastically reduced...if indeed the curve actually becomes redundant...and even undesirable.

Can't weigh in with much more advice because you didn't list the PJ your mating up the UH480 with.

That said, if you don't own such a PJ, and you ever upgrade to a PJ with "Stretch Mode", the Screen design will become an issue. so keep that in mind. Your project will involve no small amount of effort....hopefully it won't be misdirected....or worse, become obsolete.

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post #3 of 9 Old 08-13-2017, 02:05 PM - Thread Starter
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Quote:
Originally Posted by MississippiMan View Post
Ambitious.....but promising because others have tackled Curved Screen builds and come way with some very noticeably excellent results.

The size your attempting, along with the use of a Panamorph Lens does (...or can...) require a curvature, IF the projector does not have an integrated Stretching Mode. If it does...the amount / degree of needed curve is drastically reduced...if indeed the curve actually becomes redundant...and even undesirable.

Can't weigh in with much more advice because you didn't list the PJ your mating up the UH480 with.

That said, if you don't own such a PJ, and you ever upgrade to a PJ with "Stretch Mode", the Screen design will become an issue. so keep that in mind. Your project will involve no small amount of effort....hopefully it won't be misdirected....or worse, become obsolete.
Good thoughts. My projector is a plebeian optoma hd28dse ... projection distance is 27 feet. it does have a "letterbox" format that does the vertical stretch. I put a scope movie, turned letterbox on and slid the Uh480 lens in place. I could instantly see a small pncussion that required about 3" raise at the left and right of the screen to disappear. I hope my experiment was spot on... I will advise if I get a pie in the face lol...
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post #4 of 9 Old 08-13-2017, 04:10 PM
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Yeah...I've used that Optoma when I needed a longer Throw Projector. Part of your problem is the older A-Lens's optics....the rest is owed to the PJ's LBX Mode's minimal ability to process the "amount of Stretch" needed. The HD28DSE's LBX mode was/is intended for use with Letterbox sources (non-16:9) to stretch to fill a 16:9 area at full resolution.* The Panamorph Lens is really intended to change a 16:9 source into a 2.35:1 format. *The HD28DSE also has a "Superwide" Mode to fill a 16:9 area, but that crops the ends of the 2.35:1 image....)

Projectors that have more intensive Stretch Modes to stretch 16:9 Content do so to counter the effects of A-lenses.

But there are physical / optical limitations inherent in certain "older" A-Lens, and those limitations are tied in with Throw Distances and Image sizes.

Under "normal" circumstances, (ie: smaller screen width) you would not see enough pin-cushion overspill to matter...and really, it's more a case where one doesn't produce noticeable image distortion at the edges. Again...at a smaller size, nothing to worry about.

The newest Generation of A-Lens optics have virtually nada pin cushion issues. But they also come in at Used Car cost. And try to buy one with a Motorized Sled?

Anyway...your going with a epic sized screen, so you solutions must also be geared toward compensation, not necessarily optimization. To do what you need to do, ya gotta warp the Screen's shape....quite a bit. And it seems you have a good plan, so get'ter dun!

.......and save the Eggs for breakfast.

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post #5 of 9 Old 08-15-2017, 02:58 PM - Thread Starter
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So today I pulled out my trusty Hitachi 15" chop saw and cut the T-slot profiles to desired length. 2 x 200" for the long beams and 4 x 91.5" for the vertical beams- two for the frame sides and two for support in the center.

As mentioned the profile is somewhat flexible, so I put the long sides on two garbage containers and marked each 1/3 of the length as well as the center. Then simply proceeded to lean in sequence on the center, left 1/3 marking and right 1/3 marking until I achieved some curvature. It was way simpler and effortless than I imagined it...

Now I am waiting for my 8020 slide in hook ears (x3) which will be used to suspend the screen from the ceiling: https://8020.net/12016.html. Once they are here I will proceed with the final assembly.

Pictures of my trusty Hitachi miter saw and my bending rig lol...
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Last edited by partcrash; 08-22-2017 at 08:58 AM.
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post #6 of 9 Old 08-21-2017, 12:57 PM - Thread Starter
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The weekend was eventful. I sprayed the t-slot pieces flat black and built the frame. Took all 30 minutes. Then I unrolled the screen material and started stretching it.

On screen size, I decided to build it as big and as tall as possible and then mask according to the projected format. So the frame was 204" wide and 94" tall as the Centerstage XD was 98" tall and I needed 2" on each side for fastening.

Speaking of fastening - a word on the dowels- the 1/4 dowels I wanted to use to affix the screen material were too narrow and fell through the 3030 t-slot... and the 3/8 (0.375) were too big and didn't wedge properly. So 0.3125 dowels would have been perfect, but I could not find them at my local store... So I bought a few 4 feet long sticks of poplar wood with 0.3125 diameter and chopped them to 3" or so long dowels.

Stretching proved difficult for such a large screen. It took a lot of effort and repositioning to get the desired effect. It took solid 6 hours on my fours ... and it is still work in progress... the material is very sturdy and does not stretch. So any mistakes you make only amplify as you proceed and you have to roll back/ undo quite a lot to make sure things look nice. Two people would be easier, but I got no help (actually I got help from the wife- she said- go ahead- build that monster. Fair enough). I used a small rubber mallet to wedge the dowels completely/ flush into the t-slots. I ordered some 4" border tape so hopefully it will cover some of my less successful handy work on the edges as well as the extra material sticking out on the sides.

On mounting the screen- I purchased 3 wall/ ceiling pulleys (2" from Lowe's) and attached them to the ceiling. Then ran long pieces of picture wire (the thicker twisted kind) through them. On one side I attached them to hooks on the back wall and on the screen side I attached them to some hooks I bought from (you guessed it) Lowe's. The hooks have a machine thread end and a nut. The nut fits perfectly into the t- slot profile and you can screw the hook in making a solid connection. The idea is that once I built the screen flat on the floor two people can pull the other end of the picture wires and hoist/ lift the screen via the pulleys. It worked like a charm.

Now my body is sore and I am waiting on the velvet tape to show up.

The screen is fairly transparent and you can see anything that is not black behind it. I thought I can get by using a few acoustic tiles where it mattered, but I have now ordered another 200 tiles to cover the whole wall behind the screen- including the two windows. Yes, having two windows behind the screen is not helping lol... I probably will use some of the blackout material from the old screen, spray it black and make blackout shades to fully block the windows. I might do it with acoustic tiles too. We shall see.

See pictures for my work in progress. Overall it went somewhat enjoyable and I didn't hit any snags.

Total rough price for the screen was 3 x $85 for the 6 meter 3030 t-slot beams, $30 for corner brackets, $450 for the Centerstage XD material, $11 for 2 cans of spray paint, $15 for three hooks, $15 for three 2" pulleys, $10 for 100 feet of picture wire, $30 for 60 feet of the border tape ... for a rough total of $815...

Finally I popped "Fury", turned on letterbox format on the projector and slid the anamorphic lens in.... and I absolutely, unquestionably got blown away. What an eye candy. All my body aches were well worth it... my front row sits 19 feet away and the distance was perfect to make you feel part of the movie, THX guidelines be damned...

Stay tuned for pictures of the finishing touches progress and hopefully the final result
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Last edited by partcrash; 08-21-2017 at 04:46 PM.
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post #7 of 9 Old 08-22-2017, 12:52 AM
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Quote:
Originally Posted by partcrash View Post
On screen size, I decided to build it as big and as tall as possible and then mask according to the projected format. So the frame was 204" wide and 94" tall as the Centerstage XD was 98" tall and I needed 2" on each side for fastening.
.. my front row sits 19 feet away and the distance was perfect to make you feel part of the movie, THX guidelines be damned...

Stay tuned for pictures of the finishing touches progress and hopefully the final result
I think you're right in line with THX guidelines...seating-distance about 2.5X screen-height.
Your indoor screen is larger than many outdoor screens on AVS.
That's crazy, but awesome.

How are you liking the image brightness on the XD material so far? Is the projector handling it pretty well despite the huge size?

Easy $25 DIY black (or any color) ALR paint +$40-$50sprayer screen mix smooth/clean and very easy to learn spraying with little/no mess.
Simple $25-40 DIY black/dark-grey ambient-light rejecting screen, grab two things from a local store..mix..roll..done.
Quick <$250 dedicated black-fabric theater room "A store that sells blinds can help your picture more than a store that sells projectors many times." -bud16415
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post #8 of 9 Old 08-22-2017, 08:53 AM - Thread Starter
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Originally Posted by Ftoast View Post
I think you're right in line with THX guidelines...seating-distance about 2.5X screen-height.
Your indoor screen is larger than many outdoor screens on AVS.
That's crazy, but awesome.

How are you liking the image brightness on the XD material so far? Is the projector handling it pretty well despite the huge size?
I believe that the XD might have been measured to be actually a 0.9 gain (vs the advertised 1.2), but in my setup it appears brighter and with more visual pop than the Carl's blackout with 1.0 gain. So either the XD is more than 0.9 or the blackout is less than 1.0. One area where the XD wins hands down is detail- I find it presents a much more detailed picture - to the point where you can actually see the limitations of the 1080p. The projector as mentioned is Optoma HD28DSE - it is a low end projector, but throws 3000 lumens (probably 2500 when calibrated) and in my light controlled room it works well even for 3D movies (which I love btw).

On a unrelated thought- I didnt mention it before, but I have decided to add variable curve feature - thus futureproofing the screen to an extent. I built the screen intentionally with 0.5-1" curvature - less than I needed (I needed 2.5- 3" raise to eliminate pincushion in my setup) with the intent to be able to provide more curvature if needed by tensioning/ bringing closer the left and right side of the screen. This should be fairly easy as I can run thin picture wire (painted black) along the velvet borders connecting the top corners and another wire connecting the bottom corners. The wire will not be visible by the audience in my light controlled room as it will not be in the path of the projector light. By tensioning the top and bottom wires I can curve the screen more or less depending on what I need. The frame is very flexible and springy, so it should have no problems with some tension...

Btw, I spent a few more hours tensioning the XD material and I finally like the outcome- The screen is nice and smooth everywhere and is ready for the border tape.

Stay tuned

Last edited by partcrash; 08-22-2017 at 07:11 PM.
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post #9 of 9 Old 08-24-2017, 09:52 AM - Thread Starter
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Yesterday applied the 4" felt border. I actually put only 2" on the front of the screen and the rest I used to wrap the fabric attachments on the side of the frame. The outcome was better than I expected and very pleasing to the eye.

Now all that is left is to tension the screen to add some more curve , or maybe leave it as is as the pincushion is about an inch and on such a large screen it doesn't bother me.

Also included a picture of the pulley "system" for raising and lowering the screen.

Overall I am very happy.

Now on to sticking the 300 new acoustic tiles to the front wall. This will wait a bit however. I will update the thread when ready to do it.
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Last edited by partcrash; 08-24-2017 at 10:37 AM.
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