Help wanted on acoustically transparent screens - I'm a newbie to this

I used to have a Stewart microperforated screen which I later switched to a Screen Research ClearPix2 screen. The Stewart came with an equalizer to compensate for the high frequency rolloff that results from some of the sound not passing through the screen. The sound that does not pass through the screen reflects off the back of the screen back towards the speakers. This results in comb filtering effects which makes dialog sound a bit muffled and gives it a slight cupped sound. I found the Screen Research CP2 screen to be a big improvement in this regard. It is so acoustically neutral that it was able to pass THX certification requirements without the need for external equalization. It is pretty much impossible to notice any difference in sound with a speaker in front of or behind the screen material. Moire artifacts which can be an issue with microperforated screens are also a non factor with Screen Research screens. The texture of the CP2 fabric disappears at about 6-8 feet. Disadvantages include high price and low gain.

Thanks for the replies so far, guys.

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Can u give me a very ballpark range that I'd be looking at for a CP2? Also, what should I expect on the gain which I'm assuming you mean the light reflectivity?


Thanks,


ss9001

You have a choice of the SR or the Vutec SoundScreen. Both are fabric materials. The Vutec being less then half the price of the SR. The SR is THX certified the Vutec is not.


I do not recommend ether of these with the Ruby. The Ruby is no light canon and will soon lose 30% or more of its light after a few hundred hours on the bulb. Because acoustic screens are - gain and 10% of your light passes through it you will lose much of the punch in the image especially after the bulbs drops in output. If you are going with the Ruby use a solid screen. Hi gain as recommend by Tryg and others.

If you must go with a acoustic screen then go micro perf from Stewart. It is also certified and you can order it with a gain. Because the Ruby is 1080 resolution that should greatly eliminate the possibility of moire but I cannot comment of this from personal experience.

Scott


The higher the resolution the less chance of moire. Many on this forum who own the Stewart MP going from 720 to 1080 will tell you this. Anyone can call Stewart for technical advice on this.

I have no personal experience with the MP and 1080 but I do know from reading it is reduced if not gone.


The MP can be ordered with a gain. It is also THX certified. I would think it had to meet the same tests as the SR. I dont think they have different levels of certification. A screen ether passes or it does not.


I do not want to get in an argument over what screen is better. My point is these screens because of their negative gain are not ideal for use with the Ruby.


Will it work with the Ruby..of course. Will you get the same wow factor everyone else is getting with the recommended high gain screens. You will never know unless seeing for yourself the Ruby on a high gain and MP.


Purchasing one of these screens is a very expensive risk for this projector. What if you get it and you are not happy and feel indeed you have no pop/life to the projectors image and want more brightness. No one will take your screen back. Your out thousands. At least do some research and talk to people ( there are plenty ) who own the Ruby and read what most are using.


Most important, watch out for dealers who tell you it will be a good combo. I am a SR dealer and Im recommending you pass. Not because SR is a bad product but based on the projectors brightness.

Alan,


Thanks also for your insight. You've just made it harder since there are 2 different opinions here. And on the topic of projectors/screens, I am a newbie.


OK, what's an "MP" that you are referring to? I'm pretty darn knowledgeable on the audio side, but still learning the video side.


My local Magnepan & HT dealer expressed some reservations on micro-perf screens due to both the holes effecting PQ and some deadening of the center and fronts. He sells Stewart and Draper. I have limited room width to deal with, and my Maggie 3.6's take up a lot of room. Replacing them is non-negotiable . Hence my interest in having the screen come down directly between the maggies or slightly in front of them. The Maggie center speaker is sitting atop a Pio Elite HD-capable RPTV about 2' behind the plane of the fronts; I would like to keep the RPTV in the room for normal viewing. His possible solution is replace the Pio with the new Sony SXRD 60" TV, but that is only an incremental increase in size over my 53". I can fit the projector in the room, but dealing with the screen is the limiting factor.


Any more thoughts? The SR screen looked promising on the audio side, but should I be looking at another PJ in lieu of the Ruby? Based on all these posts, I thought it was the cat's *ss on brightness/contrast.


For John, Alan and Scott,

Any tests on what typical dB reduction the Stewarts will give?


Thanks

ss9001

We could argue different scenarios all day like adding the additional black material as backing also hinders sound. After all it yet another material and same as doubling up on speaker grill. I know of know one who would use 2 speaker grill in front of their speakers. Most audiophiles remove all grills.

If you really want to talk whats best the purist would avoid an acoustic screen altogether. Do not put anything in front of your speakers unless it is necessary.


If its a must then I agree a fabric screen such as the Vutec and SR are superior audio performers but in this case I would recommend a screen with gain. From a picture standpoint I cannot in good faith recommend any - gain acoustic screen unless you settle on a smaller screen size but that would defeat the purpose of needing a 1080P projector.

Moire is caused by the interference pattern created when the screen door, (or multiples) align or almost align with the microperf holes. I did research for Stewart on this issue some years ago and it's easy to generate.


If you project a white field and go to max zoom then start zooming in you will see the moire come and go as the screen door comes into then out of alignment with the tiny holes.


It is easily solved by either slightly defocusing, (to render the screendoor invisible), or zooming slightly larger or smaller to cause the misalignment.


I guess it is less noticable on higher resolution devices since the screendoor shrinks as pixel density increases, (generally), thus making it more invisible.


It would be interesting for someone with a microperf to recreate this test with the Ruby and report the results since I may be going in that direction with my new theater, (once I finish building my house that is!).


Phil

Is it physically impossible for a woven screen to have either neutral or positive gain and not screw up the image?

I'm guessing if it wasn't, SR, Vutec or Stewart in the case of MP, would have made one by now.

So, if having my speakers behind the screen is a priority, I need to wait for pj with higher lumens.

Anyone have a ballpark idea what lumen output would be required to have a "punchy" image?

Up to now I've had a 92" diag, 1.0 gain but will likely be going a smaller woven screen as the above size is "custom" for both SR and Vutec.

At the risk of getting OT, Alan also alluded to 1080 being a waste with a smaller screen. At what size is 1080 a waste?

In light of Mark's post re: MP screens nullifying the advantage of higher res images, would this applying to woven as well and am I screwed if I want both 1080 & an AT screen.


Sorry for all of the questions but the above issues have been looming larger as I am planning on getting a woven screen for my in-progress HT

room and the time to order one is fast approaching.

I have 3 identical speakers ordered for the L\\C\\R channels and I want at least the center to be behind the screen.

TIA

Milt


Here is my take on 1080.


If you cannot see pixel structure from your seating distance with the your current non 1080 display then I would not run out and spend additional money on 1080 thinking your going to see a hugh improvement from the additional pixels.


If you want to go with a larger screen size or sit closer and you have a choice of 1080 and another non 1080 projector for the same money I would get the 1080.

Or if you must have the latest like most of us here then get 1080


As far as fabric screens not having any gain ( MP (none fabric) is available with gain ) I think its one of two reasons.


The holes are so small the material cannot be painted in fear of clogging the holes or the fabric is out sourced and the screen manufactures do not have the facility to spray these.

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First off, the backing from SR is the same material, so it's the same as doubling up the screen fabric. The solution is simply to pop the CC level up 2dB instead of 1dB to account for the through the screen loss.


Unless you have a very small screen, or all your seating is on risers it is necessary to use an acoustically transparent screen if you want matching speakers around the front of the room which gives you the best possible results from an audio perspective.


If you don't do that, you're stuck using a center channel loudspeaker which is such a significant compromise that it doesn't belong in this discussion.


The problem with putting all your seating on risers, is that you've already placed your listeners off-axis with the tweeter to diminish audio performance from the start. So, hell it's already compromised.


You do get that audio is half the experience, right?


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You can't make universal proclamations without knowing anything about the room the screen is going in or the projector in use. The goal isn't "my screen is bigger than your screen" it's about correct proportions paying attention to all of the details included subtended angles for all viewers which ties in to seated distance vs. screen width etc.


Depending on room size and seating distances that could be 80" width, 100" width or even 150" width.


And you're well aware that the SR screen can work perfectly depending on screen size and projector output.

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ClearPix2 from Screen Research is very close to "neutral" with the perforations taking it just below unity for the gain (.95).


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"Punchy" is a subjective term. Cinema standards are 12-16 ft lamberts. Punchy is probably twice that. Twelve is with film running, 16 is open gate.


I'll assume you're on the screen size below which is 25 square feet, and using a Screen Research ClearPix 2 and we'll target 25 foot lamberts, which is about twice the film running brightness.


The equation is simple


ft lamberts = (lumens * gain) / screen area


25 = (lumens * .95) / 25


Solving for lumens we have


625 * .95 = lumens


That comes out to 594 lumens.


If you look at Sony's Ruby, that's conveniently about what it measures at, that's with a newer bulb. So you'd start out punchy and over time, you'd probably end up between punchy and film standards.


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92" diagonal is an 80x45" 16:9 screen which is a standard size for Screen Research.

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There's no substitute for resolution, and I don't agree with Alan's point of view.


Regards,