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Discussion Starter · #1 ·
I tried search but did not come up with anything. We are hard mounting a 72" diag. perforated screen for the conference room at work. What I can not seem to find is just how far should the screen be mounted in front of the center channel speaker so that screen does not flutter. Anyone know? I was thinking around 12" to 18" but would like some confirmation before I tell them to go for it.


Thanks in advance. :)
 

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PM AVS member Dennis Erskine or post this question on the HT BUILDER forum. Dennis highly reccomends perf screens for center channel and should be able to answer this in detail. He is the resident acoustics and HT building expert.


I myself wondered about this very problem, the speaker fluttering the screen.
 

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If the screen is stretched tight and rigidly mounted you should not have problems with the screen fluttering. In my installations my center channel is about 2-4 inches from the screen. With the screen properly mounted and taut I have had no complaints from customers even when played at very loud volumes.


Oh yes, forgot to mention that you should remove the grills or any grill cloth that is on the speakers.
 

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My center channel speaker is roughly 6" behind my Stewart microperforated screen. I have no problems with fluttering even at above THX reference levels.
 

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10" behind mine. I am using the Stewart EQ in addition to a parametric EQ on the center channel line. Dialogue intelligibility is fabulous - even with the parametric EQ bypassed.


...and, yes, the grills are removed.
 

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Discussion Starter · #7 ·
Quote:
Originally posted by Glimmie
PM AVS member Dennis Erskine or post this question on the HT BUILDER forum. Dennis highly reccomends perf screens for center channel and should be able to answer this in detail. He is the resident acoustics and HT building expert.


I myself wondered about this very problem, the speaker fluttering the screen.
I took your suggestion and PM'd Dennis. Here is his answer...

"3 to 8 inches depending on the speaker. "



Thanks everyone!!!
 

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Quote:
Originally posted by Scott B
My center channel speaker is roughly 6" behind my Stewart microperforated screen. I have no problems with fluttering even at above THX reference levels.
That was, as I recall, the original THX recommendation back in the days when Tom Holman and Tony Grimmani managed the technical aspects of Home THX...about 6" from the tweeter to the screen surface.


Something to consider is the backside of the screen surface will reflect energy, creating potential resonances/peaks/nulls. It might be worthwhile to try some type of batting material suspended behind the screen around the speaker...if you experience any dialog intelligibility problems.


Charles Wood

Fosgate Audionics
 

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Quote:
Originally posted by cwood
Something to consider is the backside of the screen surface will reflect energy, creating potential resonances/peaks/nulls. It might be worthwhile to try some type of batting material suspended behind the screen around the speaker...if you experience any dialog intelligibility problems.
Should the front of the center speaker be parallel with the screen surface or should it be angled slightly to the screen? I seem to recall reading somewhere that by angling the speaker a bit it noticeably helps to reduce the sound reflection from the screen backside and the resulting resonances/peaks/nulls.
 

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Quote:
Something to consider is the backside of the screen surface will reflect energy, creating potential resonances/peaks/nulls. It might be worthwhile to try some type of batting material suspended behind the screen around the speaker...if you experience any dialog intelligibility problems.
I have found this to be true. A flat black velvet or velour material (curtain drapes) works well and is easily installed. Put it up just like hanging drapes. Also paint the area behind the screen and any shiny or light reflective objects a flat black. This also helps with perceived contrast and blacklevel. It is amazing how the brain can be fooled with the flat black coming through the perforations. This helps tremendously with LCD projectors.
 

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The procedure recommended by Dennis Erskine is to completely fill the wall surface behind a microperf screen with black Insul-Shield, which serves both purposes discussed above.


I should have added in my original post that I have five speakers behind my screen including two subwoofers and have no difficulty with fluttering. Fluttering would seem to me to be more a characteristic of the frame construction than anything else. The 10-12" speaker distance is Stewart's recommendation.
 

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Should be parallel. If you have reflection problems, you should put dampening material around your speakers on the wall behind your screen so you absorb the reflections off the screen.

Quote:
Originally posted by danstone
Should the front of the center speaker be parallel with the screen surface or should it be angled slightly to the screen? I seem to recall reading somewhere that by angling the speaker a bit it noticeably helps to reduce the sound reflection from the screen backside and the resulting resonances/peaks/nulls.
 
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