Hi,

I'm building a new HT and I'm interested in placing the speakers behind the screen. It will allow me to go with a larger screen and I like the idea of hearing the sound come out of the screen. I'll probably build a false wall to mount the screen on and then place the speakers behind it. I'm looking at using Mirage Omnisats for the speakers because I like the Omnipolar sound. I might also spring for the OM speakers but I haven't decided yet. The question I have is barring finding MMC fabric (don't really want to take the time to look) how good is the Dazian Celtic cloth? I plan to paint the area behind the screen flat or matte black to reduce any reflected light. I will also line the walls with a black sound absorbing fabric to reduce echo. Do I need backing for the cloth if the entire space behind it is black? The speakers are also fairly dark as well. I'm using a Sony 1251Q projector for the image and the room is going to be light controlled. I can't afford any of the professional screen materials and I'm looking for a good DIY alternative....

Any comments would be helpful..

Thanks,
Greg

I would trust Milt Wolfson (Danzian-East) without question. They can do micro perf- but if you are doing a big screen it gets expensive.

What is your budget for your transparent screen?

If you go the micro perf route - you will definately get severe comb filtering with an omni directional or any other type of speaker for that matter.

You might want to consider using a more directon center channel to improve dialog.
Acoustically transparent may be a misnomer. More accurate is to think of terms of being acoustically neutral - as attributed by noted poster here John Kotches.
John owns and swears by the latest acoustically neutral screens from SCREEN RESEARCH. Nothing is transparent. A simple pane of 1/8th inch clear glass in front of a projector's lens creates a 10% loss.

Check out their web site at Screen Research with a dot com at the end of it.

I've been using the Dazian Celtic Cloth for my screen for almost a year and love it. My speakers are placed within the limits of my screen, allowing me to go with a much larger screen size. Plus, the dialog localization is amazing.

I fabric does "taint" the sound a bit. It tends to subdue the higher frequencies some and overall drops the output by around 1db (at least for me). Both of these issues were easily resolved and overlooked.

You may experience more problems due to the type of speaker that you are planning on using. I'd recommend getting a sample of the fabric and doing some tests on your own.

FYI, it is best to cover the screen wall in some sort of anti-reflective material. I covered my wall with black velveteen. By doing so, it actually improved the overall picture quality. It eliminated the reflective light that was being passed through the fabric and washing out the image. Here's a picture of my front wall after the fabric was installed.

Front Wall Of Theater

I've been using the Celtic Cloth for about 4 months now and I am extremely pleased with the results. As mentioned before, make sure that all surfaces behind the screen are covered with a dark non reflective material. This includes the frame and/or any braces that you have placed behind the screen. If you don't, you will see them through the fabric when an image is projected onto it. WRT the audio drop off, my fix was to remove the grills from my front three speakers which results in a boost of the upper range frequencies. The curve may not match the roll-off that the Dazian creates but it definately lessens the degree that the screen effects the audio. In my HT only setup the transitions front to rear are seamless.

Bump up for this thread as I've seen this Danzian stuff being sold on E bay for less than $100. Anyone else using it for a FP screen?? I keep going back and forth on all my options from DIY up to the Stewart Firehawk microperf.

I have been using Screen Research for ~6 months and have been very satisfied. Their attenuation is very even across the entire audio band and because it is made from a woven fabric there is zero moire with no discernible pattern.

They are on the pricey side but the performance is there. Check out their ClearPix2 fabric.

Chris

Yes I'm aware of that option. People have had good reviews of it. However the Danzian can be made for under $100 vs. about 30x times that for the clearpix. The Clearpix is also made by the French, and that completely rules it out for me. So for those two reasons I'm basically debating either doing a DIY perf screen or just buying either a firehawk perf or the lower priced but lower gain Dalite perf screen.

I can't hardly believe nobody here has built a DIY perf screen with the Danzian, so I'm still hoping someone with experience will pipe in.

Cheers.

I've been using a Dazian's celtic cloth for over a year now. I don't have anything to comare it to, as it's been my only screen but it has worked great for me. The material let's quite a bit of light through so you'll want to make sure that there is nothing behind the screen that is reflective. I just use a black sheet. If you have any more questions let me know.

My friend measured the Dazian Celtic Cloth for me and it attenuates about 1 db/octave. His measurements started at 1 kHz where it was down about 1 db and it was down 6 db by 20 kHz.

Interestingly, this is pretty close to the THX re-eq curve (which makes sense since it's supposed to account for speakers being behind a screen).

If it "lets a lot of light through" doesn't that mean the "gain" is going to be quite low?

I agree with Bugman72 and Mancubus. I have been using the coated celtic cloth for a few months with great results. It is fairly transparent to light, but so long as everything behind the screen is dark, as you plan, you should have no issues. I actually have a window behind my screen which is not totally dark (thin drapes), and the top cap of my center speaker is a light oak. Because of this, I covered the back of my screen with heavyweight duvetyne (also from Dazian), and cut a hole just big enough for the woofers and tweeter of the center speaker. It works well. I can believe the quoted 1dB/octave rate of attentuation. My five primary speakers are all identical in driver complement and crossover, and require a reduction of 3dB on the tweeter. I simply removed this from the center speaker, putting the tweeter response (roughly 2.5kHz and up) 3dB higher than that on the other speakers, which are not behind the screen. To further complicate things, I also have THX on any time a movie's playing. To me the center speaker has just the right amount of treble and does not sound muffled at all.

Pap,

Oh, I believe you are correct in saying the CCC has low gain. I believe it should be very close to 1.0. The nice thing about that is the viewing angle is 180 degrees horizontally and vertically. It's plenty bright enough for my projector which is rated at 1200 lumens in low power mode.

Aaron Gilbert

If your going to go this route then line the stage walls behind the screen with something like Johns Mansinfield theater sheild. It is black and absorbtion for light and great for sound. OR Use something like GOM 701 black behind the Danzian Screen. It is proven to be acoustical material.

Screen Research has a new line that is about 15% less with less expensive frame but still made by the French(but assembled in US) and about 20x more then Danzian.

Larry

Ok, here's a query - let's say I planned to spend about $3000 on a Sony HS20 and another 2-3,000 on a perforated screen (probably firehawk).

Would I be better off to spend the whole lump on a "better" projector with more lumens and better contrast and just use this stuff for my screen?

Difficult question I know. My baseline is that I was using a 1000lumen single chip DLP unit before with 500:1 contrast on a homemade blackout cloth screen and I was happy with the image.

Like PAP above, I'm looking at the Sony HS-20, and I'd like to build a screen about 8 feet wide (110 inch diagonal). I'm concerned that with CCC's low gain, I won't get a very bright picture, particularly with the 2.35 and larger formats.

To those writers who say they've been using the Coated Celtic Cloth for some time now and are satisfied, what is your screen size and projector? Have you tried setting up a white posterboard or something similar to see how the Celtic Cloth looks compared to a unity gain surface?

Barrie, W6DX

Yes please more information about screen size and projector chosen.

I'm using an Epson TW100H which is rated at 800 Lumens. I am projecting onto a 96"x54" screen and it is plenty bright in my totally light controlled room with light absorbing walls, ceiling and carpet. I haven't done a direct comparision between the CCC and my Draper M1300. Going by memory, the picture is comparable to my 1.3 gain Draper when it was in my light coloured ceiling wall and carpet theatre.

I have no doubt that a positive gain screen would give me a brighter picture but the point is that with my current set up I am not at all bothered by the slightly negative gain of the CCC.

I have been using the Dazian coated celtic for months now and am very happy with the results. The idea that you can use the money saved on the screen material to procure a better projector has merit. The ultimate brightness is the bottom line. The celtic material is good for this application since it is made for using in large printing machines which are a upscale version of home inkjet printers. As a result the material is coated and the fabric is flattened to make intimate contact with the printer heads and has a surface which makes it good for the light reflection. The coating is also color neutral so the printing ink is accurate. But the big advantage for me besides the advantage of having the sound emenate through the screen is that the first impression of others is that when they view the system in operation their response is that they are looking through a window opening as there is no "working guts" visible next to, above or below. The psychological experience is as important as the technical specs.

Creekside - what projector and what screen size are you using? Pics?

Don't have pics right now, I'll try later. Fortunately I own my own home so I just tore out the wall where the screen was and moved it out a couple of feet to get the space behind big enough for full range speakers. That gave me a screen flush with the wall. No problem with secondary light reflections from behind the screen by just spraying flat black including the speaker cabinets and removing grills. I had no room on one side for speakers anyway. Another approach is to put cabinetry flush on either side of the screen so it doesn't appear to project into the room. The screen is approx 7 1/2 feet wide by four feet high. I am using a Sanyo plv60ht. I had trouble with ambient light due to the screen being next to two six foot wide windows. I solved the problem by getting light proof window shades and putting a wooden channel on each side of the windows for the edges of the shades to go into as they went up and down. That blocked the light leakage around the sides which was intolerable when the sun was shining directly in. I made a valance for the shades to retract into so you couldn't see them when they were up. If I could have afforded it I would have gone with the plv70 since it has dvi input and more lumens, but then this IS a subject for us who stretch our budget for a home theater at all.

I tried to attach a pic of the screen but it didn't seem to show up after posting. What am I doing wrong? It says not to attach screen shots but there is a place to attach jpeg's which is what I did.

The Jpeg was probably too big. I belive the maximum size is 640x480. Try resizing it in your favourite picture editing software and try again.

The PLV60 I think is very similar to the HS20. I believe the plv60 is 1200 lumens.

90" horizontal is about where i was planning. You mentioned more lumens, is it something you note or just a "wish I had..." thing?

Screenshots would be great.

Can't send a screenshot now but here's a pic of the screen in daylight. The carpentry is rough since this is a home made log cabin but it works. The windows next to it show how I put the channels to block side light spillage from the shades.At first look there doesn't appear to be any speakers behind the screen. I mentioned a plov70 because there seems to be an incredible amount of energy and money devoted to wringing out the last lumen from the screens with relatively limited results in my opinion. If i had another thousand bucks I would have bought a brighter projector instead of spending it on a more expensive screen.

Is the Dazian coated celtic cloth the exact same material as what's being sold on Ebay as Dazian accoustically transparent screen material?

I've been planning to use Dazian CCC since the beginning of my project, but if the stuff on Ebay is any better, I'd definetely be willing to pay the difference.

looking forward to a response.

Why don' t you ask the seller? I'm sure you'll get a more accurate response from him/her than you would from anyone in this forum.