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Discussion Starter #1
hey guys. From posts and reviews found on here, I decided to make my own AT screen using spandex. Being in Canada, it's a little tough to find the tried and true materials(milliskin) but I decided to go for it anyway. I hand picked some spandex, a grey and white material. The grey was a little 'coarse' but it was on clearance, so I figured I'd give it a try. I paid more for the white, making sure that it was a very fine weave.


anyway, I was really happy with the results. acoustically it's imperceptible to me, and it's plenty bright with no hint or moire. BUT... it's not very sharp. at first I thought I was just bumping into the limitations of 1080p, I went from a 120" screen to a 130+, but after a little testing, I realized it was the screen reducing the sharpness.


my question is, for those who have used spandex, did you notice this? I'm wondering if it's worth my time to re-wrap with a different material, or if this is just sort of to be expected.


I don't find it bothersome, or even noticeable really when watching movies, but it's almost like my vision is going(out of focus) when viewing text(htpc).


thanks
 

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DIY Granddad (w/help)
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There are different "smoothness" of weaves of course, with the "Milliskin" variety being the generally accepted standard.

But a singularly defining factor has been the use of a "Black" Spandex as the rear layer, as this not only improved Contrast as the eye / Brain perceives such, but also helped to create a somewhat sharper image because of the better Black / White variances.

If you want the best of all and stay BIG, go with a Black under-layment (directly against the Top), and spend for a Darbee Darblet. Myself, using a Panny 8000 w/Smooth Screen tech on Spandex, found the Darby worked incredible improvements without introducing jaggies or other sharpness-related artifacts.
 

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Discussion Starter #3 (Edited)
i should be clear, i have zero complaints about the sharpness or quality of the projected image from the projector. a darblet would not be the answer for this. it's only when it's reflected off the screen that it becomes an issue

comparing the image on spandex vs the image on plain white paper, the spandex always appears slightly out of focus. at first i was concerned that it was light spilling through the first layer, and then reflecting off the second, but that didn't appear to be the case once i looked closer. i don't believe the weave is the issue, either. it's actually got less texture than any of the previous screens i've used(all matte commercial screens). but maybe it's too thin? of the fabric diffuses the light too much? which is why I came here. It seems like this might be an issue inherent with 'transparent' materials.

i know that milliskin is the standard(i would still do white over grey over black, personally), but it's not available locally, and the shipping/currency exchange prices it kinda stupid. so i guess my question is if the milliskin has any impact on the sharpness compared to a normal matte screen? if yes, then there's probably not much point in me rewrapping it. but if it's near 'perfect' then there's definitely some room for improvement, and i'll investigate better sources, or comparable fabrics. as i said before, it looks totally fine with movies. it's just with text that i really notice it.
 

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DIY Granddad (w/help)
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I realize it is a "Screen Related" issue, but I stand on my recommendations of both a Black (er) backing and sharpness enhancement.

It's not saying the PJ itself needs assistance, but it is after all the device that delivers a given image to the screen, so whatever adjustments made at the PJ are "reflected" on the screen's surface. In this case, in addition the Darbee's known ability to enhance contrast and edge sharpness helps mitigate the loss of gain reflected sharpness due to Spandex's surface absorption.

And yes...Milliskin does have an impact compared to the use of "Moleskin", a commonly used weave that is slightly thicker and coarser.

Can't do much about Canadian Import VAT though, except try to help out whenever feasible.
 

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The sharpness issue you see with milliskin spandex (when properly backed with a black backing to eliminate back-scatter) has to do with cross-pixel light contamination due to "thread glow" where some of the light of a given pixel scatters along the plane of fabric due to the relative transparency of the threads/fabric and then is emitted from the surrounding pixel locations. A heavier fabric will show less of this issue but of course have a coarser thread pattern. Coated threads like in Seymour XD also mitigate this issue but again induce a coarse thread pattern.
 

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Discussion Starter #7

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The sharpness issue you see with milliskin spandex (when properly backed with a black backing to eliminate back-scatter) has to do with cross-pixel light contamination due to "thread glow" where some of the light of a given pixel scatters along the plane of fabric due to the relative transparency of the threads/fabric and then is emitted from the surrounding pixel locations. A heavier fabric will show less of this issue but of course have a coarser thread pattern. Coated threads like in Seymour XD also mitigate this issue but again induce a coarse thread pattern.
that is what I was worried about, but couldn't come up with a coherent way of explaining it. no matter how 'precise' the light hitting the screen is, it still ends up getting diffused out. this is why a darbee would not help at all really.


it's not the end of the world, I just wanted to know if this was the compromise for having an AT screen with no texture for under 100bux, or if there was actually a better way.


I think I'd still prefer this lack of sharpness to visible texture. and I know I prefer AT.


thanks for the replies guys, probably saved me from wasting time and money testing other fabrics
 

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that is what I'm using now for the white. the grey is a similar material with a coarser weave cause it was 3bux a yard, haha.
What material did you use for the grey?
I wonder if that coarser weave behind is compounding the "diffusing"
I have some white activewear but have not purchased the black that I plan to use as back layer.
 

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DIY Granddad (w/help)
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I said the Darbee DOES help...I know...I've used it in this exact same application.

As to if you want to accept that, or go on doubting, that is in your hands.

You said it all with your statement above.

The tradeoff in sharpness is far less consequential than the Caveats other choices offer. Besides that, you haven't seen the difference using Black as a Backer yet.
 

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Would spraying the surface of the spandex (just the top layer) with bright flat/matte white paint mess up the sound transparency too much? The opaque white paint would help a lot against the light transmission while using flat/matte would minimize the chance of moire problems or texture visibility.

Could carefully painted spandex sound good?
 

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Discussion Starter #12
I said the Darbee DOES help...I know...I've used it in this exact same application.

As to if you want to accept that, or go on doubting, that is in your hands.

You said it all with your statement above.

The tradeoff in sharpness is far less consequential than the Caveats other choices offer. Besides that, you haven't seen the difference using Black as a Backer yet.
it might hide the issue, but it's not a fix. like applying a lot of EQ instead of replacing poor speakers. i always want to try to find the fix before applying the bandaid. not to mention the darbee is the most expensive option we've talked about yet, haha.

it's interesting that you suggest a black backer, i suppose things are constantly changing, but all recommendations were to avoid black unless you needed the boost in black performance when i did my initial research. i was trying to avoid losing brightness, as i have pretty good contrast/blacks with the jvc already. i was using a 1.0 gain white and 0.8 gain grey screen previously, and with the jvc the white screen performed more to my liking. so that's what i opted for the grey backing.

anyway, when i first noticed this, i figured it was the light bleeding through, reflecting off the back, and then showing through the white again. thought maybe i pulled the white spandex too tight. so i played around with the material trying to reduce the 'gap' between layers(which as it turned out was basically nothing). I tried stretching it tighter, hanging another layer unstretched, putting it in front of the wall(painted black), etc and none of it made a significant difference in sharpness.

this is all good info for the future. i'm sure this won't be my last DIY screen, so even though I doubt i'll do anything with this one, i appreciate the help for the next one.
 

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Discussion Starter #13
What material did you use for the grey?
I wonder if that coarser weave behind is compounding the "diffusing"
I have some white activewear but have not purchased the black that I plan to use as back layer.
i honestly don't know, it was in the clearance section and not labelled very well. i know it's not the same as the activewear, having both a coarser weave and a less uniform coloring

I've attached a couple pics, the first with only the grey spandex, and the second with the white over grey. the grey alone is actually watchable, but the flash obviously exaggerates the transparency. The frame was also not painted yet at that point. In the second pic, the frame is actually slightly visible for the opposite reason, the white wall behind the screen in that pic makes the black frame stand out.
 

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DIY Granddad (w/help)
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The Black acts like a attenuating factor, potentially reducing the deleterious effects as described by jjcook....although I think the effect is being overstated if indeed not presented incorrectly via assumption. I have seen no mention of this prior nor an specific examples shown, so at this point it can only be considered a "opinion".

Black serves to absorb the excess light passing through the weave, and up to this point the generally accepted viewpoint was that the lighter backings are the cause of the reduction of surface. sharpness.

As for the Darbee, it is not so much a fix as a enhancement, and even then it's not suggested as a replacement for a Black backer.

And for certain, trying the Black first does not constitute being an excessive expense.

I have recently used the White / Black combo with a JVC x750, viewing both 1080p and E-shift'ed 4K content, and by my poor reckoning things looked splendidly sharp. Myself, I hesitated getting behind the use of Black as a backing for the same reasons fierce_gt is concerned about, but experience has shown that as long as adequate lumen output is available, and supplied via a respectable throw distance, the gain loss between using a Black Backing vs a Silver/Grey Backing is negligible. The White Milliskin easily reflects enough to carry the "torch".

Ftoast,

Applying enough paint to sufficiently reduce Light transmission would in turn reduce acoustic transparancy and therein render the use of Spandex moot.

However spraying onto spandex has been done when AT properties were not at issue,
 

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Discussion Starter #15
The Black acts like a attenuating factor, potentially reducing the deleterious effects as described by jjcook....although I think the effect is being overstated if indeed not presented incorrectly via assumption. I have seen no mention of this prior nor an specific examples shown, so at this point it can only be considered a "opinion".

Black serves to absorb the excess light passing through the weave, and up to this point the generally accepted viewpoint was that the lighter backings are the cause of the reduction of surface. sharpness.

As for the Darbee, it is not so much a fix as a enhancement, and even then it's not suggested as a replacement for a Black backer.

And for certain, trying the Black first does not constitute being an excessive expense.

I have recently used the White / Black combo with a JVC x750, viewing both 1080p and E-shift'ed 4K content, and by my poor reckoning things looked splendidly sharp. Myself, I hesitated getting behind the use of Black as a backing for the same reasons fierce_gt is concerned about, but experience has shown that as long as adequate lumen output is available, and supplied via a respectable throw distance, the gain loss between using a Black Backing vs a Silver/Grey Backing is negligible. The White Milliskin easily reflects enough to carry the "torch".

Ftoast,

Applying enough paint to sufficiently reduce Light transmission would in turn reduce acoustic transparancy and therein render the use of Spandex moot.

However spraying onto spandex has been done when AT properties were not at issue,

I will have to explore the black with some testing I think, at least for my own education. I do have some black spandex material that should at least give me the idea. I just find it amazing how quickly knowledge can change on here. I swear(maybe I was just listening to different people?) that black was considered a risky venture, and only recommended if you needed the boost in black performance because of how low the gain is on a spandex screen. I was actually under the impression I was 'not following recommendations' by using a grey backer instead of white, haha. though there certainly were a large number of people who were happy with the result of white over grey, which is what ultimately led to my choice.


I'm also curious to see how paint the screen wall black will affect this. I've been through a few designs already during the build, and I'm currently totally unpainted. I question how much light is actually going through BOTH layers, reflecting off the wall, and coming back. I know the perceived contrast went from spectacular to 'data projector' when I lost all my light control and dark surfaces. I'm excited to get back into the build and make it functional again.
 

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I too noticed a bit of a resolution reduction when I began using my DIY spandex screen. Is it enough to go back to a painted screen? No. I like the speakers behind the screen so well that I just don't really care about the slight resolution reduction.

At first I used black behind white. For the fabrics I was using I rebuilt the screen and put silver behind white. I cannot recall what if anything changed about the resolution. The fabrics I used were from JoAnne Fabrics. Both layers were made from material for swim wear according to the label. I have NO idea what improvement I might get from using milliskin on a new screen. Doubt I will ever know because I have no plans now to build another screen. My projects are more to installing new speakers and processors for Atmos and DTSX.
 
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