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Discussion Starter · #1 ·
Those of you who have purchased acoustically transparent screens, do you think it was worth the extra money? Did you notice an overall improvement in the sound in the room? In retrospect, was the extra money worth it to you?
 

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Since you're not specific about your setup and/or your center channel options, it's hard to make the final call. But here's my 2 cents....


I saw (and heard) a perforated (acoustic screen) recently. Depending on your setup, you might notice a graininess attributable to the perforations being clearly (or subtly) visible.


Depending on the quality of the center channel, I've also heard there can be slight movements in the screen due to sound waves. (I was not able to turn the sound up high enough to test this possibility).


(If your setup allows it, I suspect the best solution would be dual, indirect center channel speakers placed on opposing sides (or top/bottom) of a non-perforated screen).


P.S. It also depends on how far your screen is away from a wall. The closer it is, the less need for acoustic transparency.
 

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I'm also considering a perforated screen, but not because I want my center channel behind it.


I have a 119" Da-Lite HCCV Perm-Wall mounted to my front wall, which is also covered in Theater Shield + / GOM fabric. I noticed that when I put the screen up, I have a lot more audible reflection in the room than I do with it down. It's a disturbing amount of audible reflection, actually...


I can't help but wonder how much "better" the room would sound if the screen were perforated. I've even acquired a sample of Da-Lite's HCCP (High Contrast Cinema Perf) to see if I notice the perforations. It's a 1' x 1' section and I've taped it to the top-middle of my current screen. From 3' away it looks awful, but from the seating position (~15'), it's virtually unrecognizeable from the actual screen.


Has anyone else used a perforated screen just to reduce the "slap echo" effect in their room? Did you notice an actual visual difference in when you went to the perf screen?
 

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Discussion Starter · #4 ·
I am getting ready to setup my 1st HT with a big screen.


I have Maggie 1.6's for my front speakers. They create a huge, wide sound field. One of the ways that they accomplish this is that they are a dipole speaker--they reflect the sound off the back wall as well as directly forward.


I'm sure that a big screen will add a lot to the experience but, up to this point, watching movies has been about 80% sound experience, 20% visual. The sound is very important. I've read about the theory behind acoustically transparent screens. What I am most interested is the observations of people that actually have them.


Slap echo is a new term for me. Does an acoustically transparent screen eliminate this or does the rest of the room need more deadening?



Treble and upper midrange are very directional sounds. By placing the center channel in the middle of the screen, I would guess that it adds a lot to the sound quality. Those of you that have actual experience. What are your observations.
 

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Quote:
Slap echo is a new term for me. Does an acoustically transparent screen eliminate this or does the rest of the room need more deadening?
Slap echo, clap echo...


Anyway, an acoustically transparent screen would do nothing in itself if the wall behind it weren't absorbent. As I stated, my front wall is covered with TS+ / fabric. I've got half of it covered with an acoustically reflective screen right now though...
 

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James,

I have a Stewart microperforated screen and it was definitely worth it. When I switched to a microperforated screen I was able to use three identical speakers across the front (any other scenario is a compromise). I was also able to put thick absorptive material across the front of the room in back of the screen which dramatically improved dialog and imaging from the front speakers (this permitted the absoption of back reflections from the speakers and also got rid of an echo that was due to the large acoustically reflective screen that I originally had.


Regarding what GreggPenn stated,

(1) Graininess due to the perforations are not a factor unless you are sitting very close to the screen (i.e.
 

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Why would dual center channel speakers be more prone to lobbing than 3 identical front speakers as in your setup?


Also, what frequencies would be affected?
 

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Lobing is a problem with dual center channel speakers because they are producing the exact same signal. Certain frequencies from the two center channel speakers cancel each other out and others are reinforced. The result is a nasty looking frequency response curve. This is the same problem that results in the poor horizontal dispersion of M-T-M horizontally oriented center channel speakers. Perhaps someone else can jump in here and offer a more technical explanation.
 

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If you do a search, you will find the numerous technical responses to my post. In addition to Scotts comment, I understand that the same sound would be coming from each of the two centre channel speakers. Given that each of the two speakers would be a different distance from the listener, the sound from each speaker would arrive at slightly different times.


This would cause further degredation in the quality of the sound.


FWIW, I recently ordered a Stewart Micro Perf thanks to my discussions with Dennis Erskine and with Scott.


Warren
 

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I was *very* impressed with the new Screen Research acoustically transparent screens at CEDIA Expo. The first model has just received THX certification (the second is about to). They claim significantly superior acoustic transparency to the competition (and have the audio response curves to prove it) and NO moire pattern interference.


Looked and sounded really good.



Eric
 

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Eric,


I have my eye on one of the Screen Research screens myself, so that I can pursue the holy grail of speakers, a trio of matching speakers across the front of the room.


The one downside is if you're lighting up a very large screen, as the SR screens are .95 gain for white, and .8 for Gray.


Uther, I don't have pricing info, but will request pricing from the US distributor.


Regards,
 

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Mick,


If there is an evaluation, it will need to be someone that's a bit stronger videowise than I am. I honestly don't know if Greg R, Bill C or Gary has something in the works at this time. If I am asked to provide thoughts/observations on acoustic transparency as part of their review, I will be happy to do so, but they are all equally able to judge that aspect for themselves ;)



There are a number of factors which are pointing me towards this screen...


1) I need acoustically transparent because of my penchant for large planars as my speaker of choice. Given this, it's either acoustically transparent or two speakers, one for music, one for movies. I don't want to deal with that type of hassle.


2) My room is "width challenged", so I have to go with a relatively small screen, with an 80" viewable width (~92" diagonal). Stewart, Da-Lite and Vutec have all said they would be highly concerned with Moire` given my screen size. The SR screen has no perforations, and as such it shouldn't induce Moire`.


3) The projector I am purchasing (Optoma H76 when it's available) should have more than sufficient brightness to work with, especially since I have a fully light controlled room and a small screen size. Anything > ~400 ANSI Lumens @ D6500K should be adequate. The Optoma should come in at twice that figure if it is consistent with other HD-2 based projectors.


I hope that answers your questions :)


Regards,
 

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Quote:
Stewart, Da-Lite and Vutec have all said they would be highly concerned with Moire` given my screen size.
I would have thought a smaller screen would introduce less Moire - interesting!
 

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Uther, it has to do with the size of the pixels vs. the size of the perforation if my understanding of the phenomenon is correct.


The smaller the screen, the smaller the pixel and the greater chance of interaction.


If memory serves me correctly, they recommend a 100" diagonal or larger to help cut Moire` from fixed pixel displays.


Regards,
 

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Ok, that actually makes sense. I was starting to think along those lines after I posted that message yesterday. Any ideas on how noticable it is right at the 100" range? I'm concerned that the SR screen is goingn to be extremely expensive.
 

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Quote:
Originally posted by John Kotches


2) My room is "width challenged", so I have to go with a relatively small screen, with an 80" viewable width (~92" diagonal). Stewart, Da-Lite and Vutec have all said they would be highly concerned with Moire` given my screen size. The SR screen has no perforations, and as such it shouldn't induce Moire`.


When you say Moire', are you saying this can happen when using a perforated screen with a DLP projector? I have been trying to decide what screen to get for my setup. I am getting a BenQ PE8700 DLP projector. My center channel is going to have to be behind the screen, so I was thinking of getting a Stewart Firehawk with micro-perf. My screen is going to be 16:9 and 100" wide (114" or so diagnal). The viewing will be 14' back from screen. Will I have a problem with moire' in this configuration? If so, what do you recommend?


Thanks!

Jeff
 
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