Don is trying to design a next gen cinemascope torus for the home, normally he built an outboard vaccum unit. The problem is Stewart at this point is manufacturing 17,000 screens a year and he is a bit pressed for time.

In order to make the unit less complex I told him to do what you guys did, to build the fans right into the plenum box.

For that the fan must be ultraquiet and he added that it must be BRUSHLESS;

Do any of you have a part number for such a fan?

Hopefully someone will jump in and offer the answer. Im excited to see this project progress.
Thanks to Peter!

He probably wants a 120 VAC one too, otherwise you would need a power supply.

Deron.

This is fascinating, I didn't know that people were making torus screens using live vacuam. I would assume that the material is something like mylar? How would you achieve even stretch/curvature, as I would imagine that near the edges and even more, the corners will have more tension and would cause the center of the torus to bowl, or colapse at a greater rate. I thought about building a reflecting mirror for a diferant application at one time that could be focused by a variable vacuam but I dropped the idea for this reason. For the fan, I would assume that you would want a speed control on it? Assuming the you are intending to install the fan directly into the screen, you could manufacture a noise dampening system that would remove any noise that may be left after selecting the quietest unit.

No help, but I'm very interested in the product!

Id most likely have to get a second mortgage on my house to afford a Stewart torus screen. :(

Actually I run a 120mm, 12V fan in mine with a wall bug that is set to 6VDC. It just doesn't take much to pull the material on. I purchased mine at RS year ago and because it runs so slow, it doesn't make much noise.
My suggestion would be to look at some fan's (like SilenX or other silent brands) that are 80mm or 120mm and can run at 6V.

Terry

I'm scratching my head as to why in the world Stewart would be doing this rather than a hard shell torus, and had no idea they ever did this before.

What material they are planning to use? I guess it won't be an Ultra High Gain, so still no competition for Mocom which I believe is the only hard shell true high gain torus manufacturer left.

Why no a hard shell true ultra high gain screen? Using a fan/suction and lower gain material in a torus is a diy compromise type solution, not a professional solution for a company that doesn't even sell lower end priced items to begin with. It makes no sense to me, am I missing something?

But... If they have an ultra high gain material up their sleeve and plans to offer an affordable torus where do I sign up? I'll be a beta tester. :) However I would still prefer a hard shell over a material unless there is absolutely no way to offer an affordable hard shell.

Is it a sin or something to use the name Stewart and affordable in the same sentence? I'm really confused. Is this really Stewart Filmscreens we are talking about?

Troy

A cross-flow blower may, I say MAY, slip with less turbulence noise than a fan. This will be important in a vacuum set-up...

Longer and possibly higher speed like this:
http://www.mpja.com/productview.asp?product=16783+FN
may offer different sound quality than larger diameter, shorter length units like this one:
http://www.mpja.com/productview.asp?product=15991+FN

:shock: 85 CFM! That second one will suck start a leaf blower. Probably too much by a lot, but you get my point...

I'm scratching my head as to why in the world Stewart would be doing this rather than a hard shell torus, and had no idea they ever did this before.

Agreed. If you have manufacturing capability, why would you build a screen like this?

Don is trying to design a next gen cinemascope torus for the home, normally he built an outboard vaccum unit. The problem is Stewart at this point is manufacturing 17,000 screens a year and he is a bit pressed for time.

In order to make the unit less complex I told him to do what you guys did, to build the fans right into the plenum box.

For that the fan must be ultraquiet and he added that it must be BRUSHLESS;

Do any of you have a part number for such a fan?

Hi,

does that mean the Ultramatte 300 will come back for torus applications ?

Oliver

Agreed. If you have manufacturing capability, why would you build a screen like this?


Because every TORUS screen they build is tailored to the room in which it's going in with 3 distinct signature curves the sides and different top and bottoms. It is a physical impossibility to mold a different one every time.

Hi,

does that mean the Ultramatte 300 will come back for torus applications ?

Oliver

I bet thats the white screen with gain of 2.8 2.8, in that case most definetely yes.

[QUOTE=jtnfoley]http://www.mpja.com/productview.asp?product=16783+FN
http://www.mpja.com/productview.asp?product=15991+FN
QUOTE]

Thanks Link sent to Don. Any more suggestions? The crossflow blowers can they be brushless too?

Actually I run a 120mm, 12V fan in mine with a wall bug that is set to 6VDC. It just doesn't take much to pull the material on. I purchased mine at RS year ago and because it runs so slow, it doesn't make much noise.
My suggestion would be to look at some fan's (like SilenX or other silent brands) that are 80mm or 120mm and can run at 6V.

Terry

Thanks Terry!!

Because every TORUS screen they build is tailored to the room in which it's going in with 3 distinct signature curves the sides and different top and bottoms. It is a physical impossibility to mold a different one every time.

And then add crating and shipping costs.
Potential customers would have to figure out if installation was feasible considering hallways and stairs leading to the HT.

I'm using a projector simply because it's the smallest device with the biggest image.

My understanding is that you can get the monocoque version or one that is assembleable and shipable.

Sorry for the dumb question but what is the fan for?

To suck the screen into it's proper shape that is ideal for the isco 3:

http://cineramax.com/images/Prometheus-elevation-cross-.jpg


http://cineramax.com/images/Prometheus-fp.jpg

So the screen is not attached to a mold for shape it uses fans and a frame for shape?

Correct, this shell is ray traced to the room pj and audience.

Don Stewart actually figured a way to mask these, but am afraid to ask the price.

Gotcha

I assume Cinecurve by Stewart is very different from Torus.

Another reason I mentioned the 120 VAC version of these pancake fans is the 120 VAC fans that I have had are built like a million times better then the 12 VDC ones we use in our computers. Sense it's AC there are no brushes. Probably costs way more, but if you are buying a Stewart, you expect the best.

Deron.

I assume Cinecurve by Stewart is very different from Torus.

This is a slide I put together for a local presentation. It sounds a bit as an infomercial and I am goingt to tone it down a bit however the facts remain 100% accurate.

Cinecurve is a stop gap measure in anamorphic projection. It can only be 59% efficient and runs a hot bnd in the middle . The cinecurve does have a belly, the screen sticks out in the middle where nothing can hold it in.
http://cineramax.com/images/Torus-Cinemascope-Metrics.jpg

[QUOTE=jtnfoley]http://www.mpja.com/productview.asp?product=16783+FN
http://www.mpja.com/productview.asp?product=15991+FN
QUOTE]

Thanks Link sent to Don. Any more suggestions? The crossflow blowers can they be brushless too?


Look closely... they are brush-less ;)
Those are "shaded pole" motors, which is an inexpensive form of AC motor... the same kind of motor as residential kitchen exhaust hoods and bathroom fans.

DC motors typically require brushes because they must be commutated, and brushes are the cheapest way to do so.

I bet thats the white screen with gain of 2.8 2.8, in that case most definetely yes.

Hi,

wow, that's the exact fabric I want since you first called it Xenon white here on AVS !

I want some for my curved screen but Stewart had discontinued it some time ago.
Now I have a curved screen in place and it already looks terrific, but the Vutec fabric I have is not as good as I'd like.

So can we again order the Ultramatte 300 ?

Oliver (VERY excited)

Yeah when they do my runs. I'll PM you.

http://www.silentpcreview.com/article695-page1.html

lot of info on fans they just did a review of 120mm. They think the NOCTUA NF-S12 SERIES is the best.

Thanks!!!!

http://www.thermaltakeusa.com/2005/dcfans/smartfan/a202829.htm
I just bought a couple of Thermaltake pc fans at fry's electronics for 2 torus screens I'm going to build. They are 120mm 12v brushless with a variable speed controller. they flow35-95 cfm depending on where you set the control and between 25 and 45dba. Part #a2029. Do you think these would be suitable? This will be my fist attemp at a torus screen. Is there a formula everyone use to decide on a screen curve? I've searched everywhere and can't find anything.

Terry builds them for is cleints and has a pretty set depth he uses. This was discussed a year or so ago - not sure which thread. Semi-something had a nice build thread too. Eric has been talking about building one for three years, I think.

What projector will you be using?

Scroll to the end of THIS (http://www.avsforum.com/avs-vb/showthread.php?t=739901) thread for pjackso's calculator

Thanks for the reply. I'll be using either a marquee 8000 or an nec xg75

What would some of the advatages be for someone currently running a G90 with a Stewart 1.3 screen @ 54x96?

What would some of the advatages be for someone currently running a G90 with a Stewart 1.3 screen @ 54x96?

Very bright image with no hotspotting or color shift.

My image is bright enough on my 54x96 screen, I guess the advantage would to go larger, how large could one go?

Come on, there is no color shift or hotspotting on a 1.3 gain screen.

Deron.

Come on, there is no color shift or hotspotting on a 1.3 gain screen.

Deron.

True that but that is the very limit, with torus you can go a very bright 2.8 gain of white.

True that but that is the very limit, with torus you can go a very bright 2.8 gain of white.
That's what I was getting at, higher gain screen and larger image or same size and longer tube life via lower contrast setting.

So if I may ask how wide can one go with a G90?

So if I may ask how wide can one go with a G90?

On mine I run a G90 at 106 X 60" wide Torus screen. You can probibly go wider, but as Marshal stated, I always build mine the same......because it works.
The biggest advantage is how bright the image is.
I keep getting the urge to do a stack blended, but I think that would be for a 2.35 screen that would be VERY large.....say 14-16' wide. But then I just go look at my Torus and realize I don't have a room large enough to build a stack that wide. 106" x 60" is pretty big!

So unless you want to go much larger LJG, I wouldn't change your screen.....especialy in your theater.

But before you conside building one, I would strongly suggest that you view one and make sure that it is what you want. My experience is that folks either love them or hate them. Because of the viewing angle to the top and bottom of the screen, there is a pin cushion effect. It took me about a week to get used to mine. That was three years ago and I still like mine as much as I did then.

I would love to try the Stewart 2.8 gain material. It was available when I built my first one but since it was an experiment, I didn't want to spen the extra requires to get Stewart material. Cinermax, if this becomes available, I would like to know.

Terry

That's what I was getting at, higher gain screen and larger image or same size and longer tube life via lower contrast setting.

Not on mine.....but then I like a VERY bright picture. Actually I adjust the gain and bias with the Brightness and Contrast at their defaults or 50 and 80, so I am compensating there.

Terry

http://www.thermaltakeusa.com/2005/dcfans/smartfan/a202829.htm
I just bought a couple of Thermaltake pc fans at fry's electronics for 2 torus screens I'm going to build. They are 120mm 12v brushless with a variable speed controller. they flow35-95 cfm depending on where you set the control and between 25 and 45dba. Part #a2029. Do you think these would be suitable? This will be my fist attemp at a torus screen. Is there a formula everyone use to decide on a screen curve? I've searched everywhere and can't find anything.

Here is what I came up with. The "drop" on the 106" horizontal sides is about 7.5" and the "drop" on the vertical 60"side is about 3.5" so that the total drop in the center is about 11". I've said this before but I'll say it again, the viewing angle is incredibly wide, much wider than I expected.
Also if you use a radius from your "special" center seating position you will get a much deaper screen, that was why I used a greater radius.......and it worked.
There can be a dornside, and that will depend on your room. You may have an echo produced by the screen that you have to take care of with acoustic treatments (depth of room will influence this).
On the fan, it is better to get a fan that can move volume and has good static pressure and tuen it's speed down rather than say a super quiet fan that can's handle static pressure. You are essentiall trying to pul a facuum (not really but you get the idea). I fould that it take very low RPM to hold the screen in place. I've run the same RS 120mm fan for 3 years non stop.

Terry
Terry

Gotcha Terry. Will pm you around march too.

Thanks Terry

Also if you use a radius from your "special" center seating position you will get a much deaper screen, that was why I used a greater radius.......Yeah, my understanding is that if you use the viewer-to-screen radius to calculate your curves, you'll get hellacious gain right in your "sweet spot" chair but it will drop off very rapidly from there. By using a shallower curve you "spread out" the high-gain area. Your max gain isn't as high but you get a much wider viewing area.

-Pjackso's spreadsheet lets you do that. Just specify how wide you want the viewing area to be, and it calculates the radius required for that. Or you can just do what Terry did. :)

Chuchuf commented:
> My experience is that folks either love them or hate them. Because of the viewing angle to the top and bottom of the screen, there is a pin cushion effect. It took me about a week to get used to mine. <

Thanks, Terry! Never having seen one, that was what I had imagined must be the case, but I've never gotten anyone to admit to it. ;)

- Tim

I keep getting the urge to do a stack blended, but I think that would be for a 2.35 screen that would be VERY large.....say 14-16' wide.

Terry, do you think it would be possible to blend on a torus?? I've been advised to stay away from high gain screens, and to especially stay away from curved screens.

A blend would be horrible on a high gain torus, they will accentuate the color shift badly because you will have projectors at two different positions and they'll reflect at different angles. Maybe a low gain would be ok, but not optimal, but you wouldn't need two projectors on a high gain anyway.

Troy

I wasnt saying I wanted to, I was just curious that Terry wanted to try, since as I said I've been told it isnt a good idea.

so did this stewart product ever get off the ground? what about the 2.8gain material: did it ever "materialize"? (couldn't resit)

a major suggestion:

Only industrial grade fans are reliable. Pabst would be my first pick. Their specs are correct, too, so that you can rely on them.

http://www.ebmpapst.com -> switch to English, then go to products, compact fans, axial fans.

so did this stewart product ever get off the ground? what about the 2.8gain material: did it ever "materialize"? (couldn't resit)

The product never got off the ground.
The material was the Ultramatte 300 and it never was available for sale just like that.

The highest gain that is suited for CRT projectors that is produced by Stewart these days is the Ultramatte 200 with a gain of two. If the screen is not too large it is the fabric of choice for curved screens and torus screens with CRT projectors.

I saw this 158in wide torus few months ago.
http://www.dvdfreax.com/theater/october2005/index.php
It looked even bigger in person.

That's some big ass screen there :)

The torus is very timidly curved though - less than 4% is not enough to take care of hotspotting and color shift with the Pearlbrite fabric. Very impressive theater size !

i'v used the pearlbrite before. mine had streaks. i lived with it simply because i thought i caused it by streching it over my torus frame. obviously, from other posts i see this was a defect and not my fault.

does anyone know if AVS has a return policy for this material?

It's my understanding that Vutec won't take back the Pearlbrite material. This doesn't say good things about their quality control, and it's what kept me from building a Torus screen, since there's no other suitable screen material available.

It's my understanding that Vutec won't take back the Pearlbrite material. This doesn't say good things about their quality control.

Very correct on both accounts. Most of the time the streaks are not that bad, but can be seen on bright scenes. That projectors with a curved screen throw a pretty bright picture by definition does not help matters.

If Vutec would stand behind their product and maybe even take the gain down a little to get rid of the problem they would have a killer product.

Oliver

Papst may make quality fans but they sure don't seem to have any quiet ones that move decent air.

Wes,

that's the problem with most manufacturers:

their rated specs have little to do with reality.

Pabst specs are accurate, and they indicate how they measure sound pressure level.

One just doesn't know what is right anymore after looking at and trying the popular brands for computers. They all claim low noise at large CFMs but I don't think most of them can be trusted or believed that their specs are accurate.

A user in Germany used some highly regarded PC brand silent fans (19db SPL rating) to modify a perfect condition Barco 1209s/2. He fried some boards, then decided to measure the airflow of his PC brand fans. They only moved ONE THIRD of rated CFM.

After testing some other PC brand fans with similar results, he then moved to (much more expensive) Pabst 22 or 25 db fans after confirming that they moved as much or more than the rating indicated (and they were already rated at higher CFM). I do not remember if he then slowed them down a bit to get them to the CFM he needed (which would also have reduced fan noise).

I didn't see any 120mm 22db rated fans on their site, do you have the part numbers he used in his 1209. And were they quieter than the stock fans which I think are NBMs.

Right now I'm running 2 silenx fans in the back along with one stock fan and it runs nice and cool. I've run it for over 8hrs and then opened the case and checked all the heat sinks and they were still good to the touch. But I think the silenx fans are starting to run noisier, they've been in there for about 1500hrs, which is not very good.

Cinecurve is a stop gap measure in anamorphic projection. It can only be 59% efficient and runs a hot bnd in the middle . The cinecurve does have a belly, the screen sticks out in the middle where nothing can hold it in.
[/IMG]


I have that same problem. My body/belly is unfortunately Cinecurved.:D

I don't remember which model.

I assume they were from the 4412 F/2 series though. Unfortunately it's hard to track these models down.
This site has info on 2 of them: http://www.ekl-gmbh.de/frontend/uebersicht_luefter.php3?id_matchcode=produkte

I found some data sheets on the those series, thanks.