Screen Research ClearPix2 Acoustically Transparent Front-Projection Screen
In the pre-video era, you might even have had such a screen at home. Your parents probably relied on you to set it up before that riveting "How We Spent Our Summer Vacation" slide show.
Home entertainment has come a long way since then. But for that big picture, you still need a video projector with a separate screen. Those screens now come in a bewildering variety of choices. Still, most of the screens designed for home use share one common characteristic: sound won't pass through them. This makes positioning the center-channel speaker a challenge. It also limits the choice of that speaker to one that will fit conveniently below (usually) or above the screen—a compromise that seldom provides an ideal acoustic match to the left- and right-channel speakers.
The screen in your local movie theater is probably perforated, a technique that has been used since the advent of the talkies to allow the speaker(s) to be placed behind it. Millions of tiny holes allow sound to pass through—sort of. The perforated screens in movie houses significantly affect the frequency response of the speakers. So much so, in fact, that equalization is typically used in an attempt to compensate for it. There have also been reports of theater owners painting an aged screen (new theater screens cost big bucks), trying to cover up years of neglect, wayward buttered popcorn and Eskimo Pies from those midnight showings of The Rocky Horror Picture Show, and other assorted indignities. But paint fills in many of the perforations. You can well imagine what that does to the sound.
But there's another reason that perforated theater screens are bad for home use: the perforations are too large and widely spaced. They would be clearly visible to an audience seated just a few feet away. A number of solutions have been developed to get around this problem. For example, Stewart Filmscreen worked with THX to develop what they call a MicroPerf screen. The holes in this screen are less than 0.020 inches in diameter, with 30,000 of them per square foot.
Other manufacturers, pointing to the possible visibility of the perforations and reports of moiré patterns from the interaction of the holes with the fixed pixel structure of the new digital projectors, have taken other approaches. The MicroPerf screen was developed when CRT was the dominant projection technology, but manufacturers of this and similar small-perforation screens argue that moiré patterns are only a problem in a limited range of screen sizes; below and above that range (which is determined by the pixel size), the problem becomes minor or disappears entirely.
New Kid in Town
One of the newest players on the scene is the French company Screen Research. Their ClearPix2 has already received certification from both THX and the Imaging Science Foundation (ISF). It is not perforated; instead, it is woven using microscopic fiberglass strands coated in vinyl and then woven in a propriety and patented knit design. It's also available in all of the most popular configurations, including fixed and retractable. A variety of masking systems are also available for both fixed and motorized applications.
There are two versions of the ClearPix2: matte white, with a specified gain of 0.95, and "pearl grey" with a rated gain of 0.75. Our test screen was a retractable model, in matte white, 16:9, and custom-sized 92 inches wide. While I did perform some testing at the 92-inch width, most of my viewing was with an image size of 80 inches—the width I have found to work best with most projectors from my usual viewing distance.
Our sample came with the option of an additional layer of a black backing made of the same acoustically transparent material behind the screen. This was fastened only at the top, with a weighted rod in the bottom seam to keep it hanging evenly. The black backing is designed to prevent stray reflections behind the screen. In particular, it minimizes any chance that the bright, metallic speaker drivers that are common today will shine back through the screen at the viewer.
Because of its low gain, which I will discuss in more detail further on, I can recommend only the white version of the ClearPix2 for any video projector intended for home use. This includes both budget and high-priced LCD, DLP, and D-ILA or SXRD designs. Screen Research only recommends the lower gain pearl grey material for early first generation projectors with contrast ratios rated below 600:1 and even then, counsels toward the matte white as most users will likely upgrade their projectors over the years. I do not recommend the Screen Research screens for CRT projectors in either material. Even the best CRT projectors are relatively limited in their light output.
Mounting the retractable Screen Research to my ceiling was difficult only because of its weight. The design of the case, with its adjustable mounting brackets, is quite clever and convenient, but I still recommend professional installation, particularly for any of the retractable or variable-aspect-ratio designs. That's probably good advice even for fixed-frame models; they're much lighter, but they are cumbersome to handle, and the exposed screen material can be easily damaged during the installation process.
An acoustically transparent screen is a real boon on film soundtracks. There's something very appealing about having the dialog coming from the screen, where it belongs.
I positioned only the center speaker behind the screen; even a 92-inch-wide image is just a little too small to cram all three speakers back there and still keep the left and right speakers spaced far enough apart. But a big plus for those who do want to put all three front-channel speakers behind the screen is the fact that the black borders at the left and right of the retractable screen are made of the same acoustically transparent material. It also helps that the ClearPix screens do not require the tab-tensioning system that other retractable screens require along their edges to keep them hanging flat. So there's no solid "frame" at the sides to cause acoustic problems if the left and right speakers are located behind and near the outside edges of the screen. (There will, of course, be a hard border with the fixed-frame models.)
The ClearPix2 is as acoustically transparent as its makers claim. I could measure only the slightest rolloff in the high frequencies above 6kHz (see "Tests"). The benefits of having the center channel behind the screen far outweigh this small loss.
But that was not the only benefit. I heard a more uniform soundstage across the three front channels with the center speaker at nearly the same height as the left and right. Everything just snapped into a tighter acoustic focus. While I've never had any real complaints with the below-the-screen setup I've used for years, I was genuinely impressed by how much more solid, cohesive, involving, and, when required, dynamic things sounded with the more elevated center speaker.
The ClearPix2 also makes it more practical to consider a setup with three identical speakers across the front. A tall floor-standing or stand-mounted center speaker—the same model used for the front left and right channels—is now a real option. And when it's time for multichannel music, raise the screen and enjoy the audible (and visual) coherence you'll get from three matched front speakers. This is a benefit of acoustically transparent screens I intend to make use of in future speaker reviews.
The best screen material is still a smooth, neutral-white surface. Any textured material, whether perforated or woven, may well affect the image you see, depending on your visual acuity and how close you sit to the screen. Ninety-nine percent of the time, seated about 12 feet away from an 80-inch-wide image, I saw nothing from the ClearPix2 but a gorgeous picture, dependent only on the quality of the projector.
How gorgeous? I used the Screen Research during most of my review sessions with the Fujitsu LPF-D711W LCD projector. If you've read that review, I don't have to tell you here how great an image that projector produced. I rated the Fujitsu as one of the three best projectors I've reviewed in the past five years, an opinion that was largely formed by using it together with the ClearPix2.
And the other 1% of the time? When I first set up the Fujitsu, I mounted it on a high shelf, about six feet off the ground, angling it down slightly at the screen. With this setup, there were subtle but noticeable, closely spaced vertical lines running down the entire image. This was nothing like the sort of moiré patterns I'm familiar with, or the uneven vertical bands you sometimes see with digital projectors, but just thin lines, evenly spaced across the screen. It wasn't pronounced, but you could see it without difficulty in large, uniformly bright areas. When I repositioned the projector, however, the lines disappeared at my normal viewing distance. No digital keystone correction was used at any time.
But I had not only lowered the projector when I repositioned it. I also moved it further back, readjusting the zoom and focus to retain the same 80-inch wide image. I also discovered on later investigation that if I zoomed out to fill the full 102-inch width of the screen, the lines would disappear even at a shorter throw distance. As far as I could determine, the height was not a factor in the visibility of the lines.
I did not experience this problem at all with two other projectors: a Faroudja DILA1080pHD (1920x1080) and a Yamaha DPX-1200 single-chip DLP (1280x720). (Reviews of both are in progress.) The lines were very likely due to pixel spacing, or, more specifically, the gap between the pixels, which is wider on LCD projectors than with either DLP or D-ILA designs. The Screen Research did work extremely well overall on the Fujitsu, but it does need to be carefully matched to the both the screen size and distance. The further back you position the projector and the larger the image you project, the less likely you are to see this problem.
I also occasionally noticed a subtle grain in the image with the Fujitsu and other projectors. It looked suspiciously like the weave in the screen material. But it came and went, and it was never really pronounced enough to bother me. It also appeared to subtly accentuate the grain present in less-than-perfect program material. Enabling a touch of video noise reduction (available on many projectors) helped keep this in check.
The only significant video issue I had with the ClearPix2 was its low gain, even with the white material in our sample. I address this issue in more depth in the Tests section, so I'll only point out here that you need to carefully choose the projector and screen size you intend to use with the ClearPix2 if you want to avoid a disappointingly dim image. Incidentally, the screen's low gain was a fine match for the Fujitsu projector in my favored 80-inch-wide image size, helping that projector achieve a good balance of light output, contrast ratio, and deep blacks. It was also effective at the screen's maximum 102-inch width, though at my seating distance that size tends to be a little overpowering.
I also strongly urge buyers to opt for the acoustically transparent black backing material that Screen Research offers with the ClearPix2. Without it, there's a definite risk of reflections from behind the screen. I used speakers with shiny metallic cones and domes behind the screen with the backing in place and experienced no problems with reflections. Screen Research claims that the backing blocks 99% of the light from passing through the screen. If the remainder should then reflect off a light-colored wall, the backing will block another 99% of what's left as it passes back through it, effectively eliminating any effect on the picture.
This 99% light blockage sounded like a lot to me, but my admittedly rudimentary measurements suggest that it might not be far off the mark. Nevertheless, I'd still personally want the wall behind the screen to be a little darker than pure white (never the best choice for a home theater in the first place), and would definitely think twice before putting anything super-reflective, like a backup television with a reflective screen, behind the ClearPix2. My setup didn't allow me to test these worse-case scenarios. Just call me super-cautious.
The choice of any screen involves compromises, either audio or video, and sometimes both. But in my experience, the advantages offered by the Screen Research ClearPix2 are significant and well worth considering for those who want to get the undeniable advantages of locating one or more of their front speakers behind the screen. It's not without its own tradeoffs, but with the right choice of projector and screen size, I highly recommend it.
Highs and Lows
• Significant improvement in the solidity of a film's soundstage
• Allows a wider choice of center-channel speakers, including three identical speakers across the front
• Superb acoustic transparency
• Low gain makes careful matching to the projector critical
• Some combinations of viewing distance, image brightness, projector type, and setup may generate visible artifacts.