acoustically transparent projector screen material? (1 Viewer)

[David_Rivshin]

Wasn't sure if this fits better in the HT construction forum or here, so I flipped a coin

This is largely a hypothetical question for now, but I've been considering putting an inexpensive front projector (along the lines of a Panny L300u) in my apartment living room. The design would have a fixed panel style screen attached to the ceiling with hinges so it could be moved out of the way. In the down position it would be infront of the existing TV which has the center speaker placed ontop of it. This would, of course, place the center speaker behind the screen.

So, I would need a screen material which is acoustically transparent, and yet suitable to project an image onto. The only acoustically transparent commercial screen I found is the Da-Lite model, but that would run me in the neighborhood of $600. I'm not willing to spend that much money on a temporary screen for a $1700 projector. In addition I've read that such perforated screens cause moire patterns with fixed pixel projectors, which makes alot of sense.

So here comes the actual question: Does anyone know of a material which is at least largely acoustically transparent, suitable for projecting an image onto and can be had for a reasonable price? I can build the frame, etc, myself if I can find the fabric separately. My receiver is a Sony DA5ES, so I do have a simple 3 band parametric equalizer at my disposal for the center and can correct for small problems.
I know burlap has been said to be acoustically transparent, but I would think that it would produce a very fuzzy image.
The only thing I could think of so far is linen or cotton, perhaps from a sacrificed bed sheet, but I have no idea if it's acoustically transparent enough.

Any thoughts/suggestions? Any other problems I should consider?

Thanks in advance,
-- Dave

 

[Rick Guynn]

There are a few materials which can be used. I have been doing alot of experimenting myself, prceisely for the same reason you have listed. What I have ended up with is what is referred to over on AVS as 'MMC' or Max's Mystery Cloth. This is a polyester fabric with a slight sheen on one side and good acoustic properties.

The problem is that it is not the easiest stuff to find, as it seems that just about every fabric store seems to call it by a different name. The place where I got mine called it Polyknit Sheen. It was about $8/yd and on a 60" wide bolt. I found some other stuff, very nearly identical, called 'sexy satin' at a costume shop, but they wanted $15/yd for that stuff (!)

Another more easily found solution is Celtic Cloth from Dazian. Although I have not been able to shoot a picture onto the Celtic cloth, just looking at them I would say that the MMC-type cloth would produce a much better picture. I have tested the acoustics, and the MMC beats the Celtic there as well.

The other thing you have to watch for is that since these fabrics allow sound to pass through (mostly anyway), they also let some light bleed through.

Good luck.
RG

 

[David_Rivshin]

I've read all the info over at AVS; exactly what I was looking for Unfortunately it does seem that you're right about MMC being the best choice. I say unfortunately because I'm not sure I could recognize MMC if it was staring me in the face. It would be ideal if someone could find a trade name for something like MMC which could be ordered with confidence...

As for the light problem, yeah, that'll be an issue, especially with a highly reflective TV right behind the center of the screen. What do you think about putting some black speaker grill cloth on the back side of the frame? Granted it would also let some light through, but hopefully cut it down quite abit. I'm unsure about the acoustic impacts of that, though, given the air gap.
Second option is to get a large sheet of a heavy dark fabric and hang it right infront of the entertainment center. I'd have to cut a hole for the center channel (obviously), but maybe that would work out best.

-- Dave