Acoustically Transparent!  

I first saw a perforated screen at a dealer's demo of a Runco CRT. I didn't realize that the screen was perforated until I got to within 3-4 feet of the screen. I have read that ideally you should sit 12-14 feet from a perforated screen. You should visit a dealer displaying one of these screens to see if it will work for you. Discussions regarding these screens have popped up a few times, so you may want to do a search for more info. The most recent discussion is at: http://www.avsforum.com/ubb/Forum5/HTML/000478.html
FWIW, I purchased the Stewart THX microperf for the setup that I'm building.

Bryan,
I think perf screens are awfull. I went to look at the Stewart version and could see holes from the viewing distance of 12 ft. The holes looked a bit like pixels, highy undesirable in my view.
Another issue with perf screens is their abilty to eat light. As not all of us owns G90's I would prefer my valuable light not to be lost down little black holes.
I also dont agree with these things being accoustically transparent. Thinking about this logicaly, there is more screen material than space (holes) per square inch/foot, so how can they be transparent to sound. They should change this statement in their brochure to PARTLY transparent too sound.
I ended up buying the brilliant Stewart Studiotek 130 Tab Tentioned electric. Simply the best.
Eric

Bryan, I'm going to chime in here . . . . instead of another parallel thread.

I'm considering using a perf screen, instead of tilting the center channel upward toward the ears - the pros and cons. The screen will be 16:9, approx 9' wide and 5' viewing height, plus black border, with bottom edge at 24" from floor. Center channel speakers will probably be Nautilus 805 or Veritas 2.2 (see other thread on speakers).

Here's my understanding of the "issues":
1. Perf screens allow sound through, better than non-perf, for center-channels; but how well?
2. Screen may subtly alter the timbre or accuracy of sound
3. Tilting center channel up, while below bottom of screen, may give less of a continuous soundstage, due to the L/R speakers being at seated ear level.
4. This room is a library first, HT as second use, but we are striving for best quality HT experience possible. If speaker below, requires custom cabinetry that looks funny, as contrasted with base doors and drawers on either side. (obviously unique to my situation)

Are other folks able to see the perfs at 8-12'? Have evidence, or experience with non-transparency of acoustics? Or with tilted center channels?

Any guidance would be greatly appreciated.

Stew M

Stew,

You don't mention placing the center channel above the image. This is also possible if you have more space between ceiling and top of image than is strictly necessary. You can order a non-perfed screen with a perfed black masking leader at the top of the screen. Even 12 or 14 inches high. That can sometimes place the center closer to the level of the L + R than placement below the image, depending on how your speakers and screen are arranged.

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Thanks,
Kirk

I have a Stewart microperf screen, largely because my ceiling height is abnormally low--6' 7" floor-to-ceiling. The room, obviously, was not designed as a projection room http://www.avsforum.com/ubb/wink.gif With my 92" diagonal screen size (16:9), the bottom of the screen is just 20" from the floor, and there is NO space above. I can adjust it a little in either direction, but not really enough to get the center channel up to a decent level. So I'm pretty much stuck with a microperf screen in this house.

I can't say I'm happy about that - I am 13+ feet from the screen, and I can still EASILY see the perforations. It's especially bad in my case, because my projector is an LCD model and the screen dooring is visible if I get much closer to the screen than 12'.

When it got installed, I was -stunned- at how much light went through to the wall behind! It's a regular picture back there! I definitely advise going with a pretty high-gain screen unless you are in a really controlled environment. Mine's a 1.7 gain model and is just barely sufficient with my 1000 lumens projector and a partially controlled light environment.

I'd advise more than one careful screening before choosing to go with a microperf screen, based on my experience. I looked at this very model of screen, and I htink that the one in my installation is much more noticable than the one at the store. I think part of that is the projector (theirs is on an 8" CRT) and part of it is just the environment.

As far as the audio, though, I can't say that I'm disappointed. Mine came with a small device that is placed in the audio chain for the center channel. It compensates for the rolloff of the high treble through the screen. I am pretty picky about my L-R speakers for music, but I'm not so picky about center for movies, and to my ears (which are often distracted watching movies), the audio response is just fine, even through the screen.

I guess I could dig out the old Stereophile test CDs to measure the response difference if someone's that interested...

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Brian

Brian,

Is the screen that you have the THX approved Micro Perf? The one that I have is Stewart's regular Micro-Perf and the holes dissappear at 14 feet. Plus there is no image behind the screen.

Lee

Lee,
The screen that I mentioned in my earlier post WAS the micro perf.
Eric

I didn't know that a) THX certified screens http://www.avsforum.com/ubb/redface.gif or b) that Stewart had THX models in their lineup. In retrospect, A is pretty obvious, and given A, B is also inevitable.

So no, I'd guess that mine's not THX certified. Bummer--big mistake.


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Brian

You can get a perforated screen from Stewart that has larger holes than the THX microperf screen. (I think that this is the material that is also used in commercial theaters). As I mentioned above, I couldn't see the holes on the THX version until I was 3 to 4 feet away. Stewart will send you a free sample of their screen materials. I obtained a sample of the THX 1.5 gain material before I ended up purchasing the screen.

After reading multiple postings here and on other boards it has been brought to my attention that there is a lot of confusion about perforated sound screens. At Stewart Filmscreen we manufacture two types of perforation patterns. The first one is called Cinema Perf. It has approxmitly 5500 Holes per square foot with a hole diameter size of 42 thousands of an inch. The total screen loss is about 8-1/2 percent of the viewing surface. It is designed to be used with large venues on seamless screens up to 40' by 90 feet. The viewers must be over 16 feet away from the screen in order not to perceive the perforations. The hole design pattern was meant to be used with large professional sound systems that employed high frequency horns behind the screen. After the screen and sound system are installed the system has to be equalized and tweeked with sound analizing test equipment. This perf design was never intended to be used in a small screen environment and certainly not with consumer dome tweeter type speakers. As the custom home theater industry evolved we had hundreds of request to produce a sound screen for home theater enthuiast so that they could create a cinema like environment. With the help from the folks at Lucas Film we developed the Micro perforation pattern. Next, we built an exotic machine to perforate screen fabrics up to 12 feet by 24 feet in length.
The mico perf holes are 20 thousand of an inch in diameter, or about the size of an ordinary staple shaft, with almost 30,000 holes per square foot.
The amount of screen loss is slightly over 10 percent. The holes are difficult to perceive at over 8 feet. The screens come with a sonic processor that was designed by Tom Holeman. The sonic processor has the screens sound signature burnt into it and their is less than one db of sound pressure loss across the 20-20,000 freq. spectrum. The sonic processor has a built in automatic on-off feature when used with electric roll screens. When the screen is in the down position the sonic processor is turned on, when the screen is rolled up the processor is bypassed.
The Micro perf screen is the only screen in the world to be THX certified for both sound and visual performance. The mico perf screen is now used by many Hollywood film studios for post production sound mixing. The speaker(s) should be placed from 2 to 12 inches behind the screen. For best performace the wall behind the screen should be painted black to absorb the 10 percent of the light passing throught the screen.
For the most part the Micro perf screens have a history nitch of being placed into the larger very serious deditcated home theater rooms. It was never intended to be a fix all and answer the needs of the mass market.

Regards,
Don Stewart
Stewart Filmscreen Corporation

Don,

Welcome to the AVS Forum! What a pleasure it is to have you with the Forum.
Yes Don Stewart is the Stewart of Stewart Filmscreen Corp.

Don, I met you 10 years ago at the CES show in Chicago. You were standing outside the enterance to the HDTV Demo room where you provided the screen. I wanted a perf screen and had some material from Hurley which I showed you. I was very concerned about the size of the holes. You told me that Hurley only made commerical screens and your Cine-Perf had much smaller holes that would dissappear at 14 feet. Well they did and I have always been VERY pleased with your product. I ordered a 1.85 AR Screen with the then available Silver 300.

In 1997 I upgraded to a 16x9 60x107 with both 1.3 White and Silver 400, both Cine-Perf'd. American Audiophile of Lynbrook is my dealer.

Don, stay with us here at the Screens Forum. I am sure you have a wealth of information to offer us along with some interesting stories from the past. Please share with us some of your "interesting" installations.

If I were to write a motto or sales pitch for Stewart Filmscreen, it would be; "You pay more...but you get more!"

Lee

WELCOME, DON

Jeff

Thanks guys...for the warm and fuzzy welcome.

Bryan,
To answer your question: How do we make 40 foot by 90 foot one piece seamless screens: We manufacture all of our rear projection and front projection skins in house utilizing a proprietary casting process in huge molds. This way we have full control over raw materials and optical coatings.
Regards, Don