First Reflection point on Ceiling - AVS Forum
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Old 09-13-2007, 07:02 AM - Thread Starter
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Would it be better to use 4" Mineral Wool on the ceiling's first reflection point or will the 1" linacoustic work just as well?

Thanks.

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Old 09-13-2007, 09:40 AM
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Originally Posted by tradewinds View Post

Would it be better to use 4" Mineral Wool on the ceiling's first reflection point or will the 1" linacoustic work just as well?

Thicker is always better. Early reflections are mainly a mid and high frequency issue, so 2 inches (not 1 inch) would be thick enough. But thicker is better because it gives that much more bass trapping in the room.

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Old 09-13-2007, 10:07 PM - Thread Starter
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Thanks, Ethan. I'll put the 4" Mineral wood behind the complete 8' x 9' star ceiling box. I am hoping to use a AT cloth wrapped around a large 8' x 9' frame for the stars but fear it may sag so I may have to use Styrofoam as a backing for the frame and AT cloth. That means the mineral wool would be behind the Styrofoam. Would this be an issue that will negate the purpose of the mineral wool?

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Old 09-14-2007, 12:13 AM
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If the styrofoam is what faces the speakers, then yes that will degrade the absorption. Use something else like chickenwire or wood slats.
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Old 09-14-2007, 06:52 AM - Thread Starter
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Thanks Jesse. chickenwire....would have never though of it. Is there a special type used or chickenwire in general?

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Old 09-14-2007, 08:49 AM
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I think you will need some kind of backing, not only to prevent sag but to prevent light bleed through the fabric. Light leaks through the sides as well as the ends of the fiber optics. I used 1" FRK faced OC 703 in my star ceiling panels, which are about 4'x 5' each. I put the foil facing the room and removed the foil in areas where i wanted first reflection absorbtion. You could probably use kraft paper glued to unfaced material as well, but you need something to cover at least part of the surface to prevent over-absorption. 2" might have been better, especially in preventing sag, but my ceiling is already very low. I used spray adhesive between the fabric and OC 703 to keep the fabric from sagging because it sagged on my first panel, despite efforts to stretch it as tight as possible.
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Old 09-14-2007, 09:38 AM - Thread Starter
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Jon, thank you very much for the advice. I really did not consider light bleed which you are right will be an issue. I will have tons of Linacoustic left (I have the 59-1/2" ones). I was hoping to use that somehow but not sure how to support it since it is not rigid as the OC703.

I may need to come up with a matrix pattern frame, use the Linacoustic, wrap it with fabric and the use a ton of eye hook and wire to support the middle. I have no idea, it is just frustrating trying to counter gravity.

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Old 09-14-2007, 09:49 AM
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i used 2'x4' pieces of OC 703 and built a grid with 1x2s. Panels were 4'x5', so there was a piece about 1'x4' between 2 2'x4' sections. Because of the sagging problem, i would be inclined to use even 705 over 703 if i was starting again. I think using Linacoustic is begging for problems. Maybe you can roll it up and put it in the corners as bass trapping:-)
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Old 09-14-2007, 10:10 AM - Thread Starter
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I am find it difficult to get OC 703 and OC705 locally. I was hoping not to use multiple panels to avoid seams. Do you have 3 panels individually wrapped or 3 panels all wrapped together? Thanks.

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Old 09-14-2007, 12:07 PM
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I have 6 panels individually wrapped, then mounted to the ceiling to thin nailing strips. The joints are definitely visible, but my room isn't used that much when fully lit and you can't see them in the dark:-). If you can solve the structural issues i suppose you could make one large panel from smaller ones, but you still have to resolve the problem of fabric width. I used black GOM which is 64" wide (i think). i don't know of anything 8' wide. Also, you will need a lot of friends to put up a single panel that size.

If you are in or near a large metro area, there may be a SPI warehouse near you (www.spi-co.com) that sells 703/705. Also, bpape here of the forum may have it. I think fabricmate also sells it (www.fabricmate.com).
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Old 09-14-2007, 12:20 PM - Thread Starter
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ok, thanks. My SPI does not sell it for some reason. No OC stuff only JM.

I know the Janus cloth comes in 120" so I was hoping to use that.

In the end, I may need to do individual panels. BTW, how did you mount the it to the nailing strips through the cloth?

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Old 09-14-2007, 12:51 PM
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Quote:
Originally Posted by tradewinds View Post

ok, thanks. My SPI does not sell it for some reason. No OC stuff only JM.

Try these guys for mail-order:
http://acoustimac.com/products.asp

Quote:


In the end, I may need to do individual panels. BTW, how did you mount the it to the nailing strips through the cloth?

Consider the RotoFast connectors. Very secure.

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Senior Contributing Editor, Stereophile
http://www.stereophile.com/category/music-round

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Old 09-14-2007, 03:38 PM
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Check out the sticky for Chameleon Bass Traps on this construction forum - i'm pretty sure they sell it.

I glued 1/4"x2 trim boards to the ceiling with liquid nails, then nailed through the edges of the 1x2 frames with a finishing nailgun. The finishing nails disappear thru the GOM.

I haven't put up the final panels at the back of the room due to consrtuction. I will need access to the ceiling for cables, etc. so i plan to hinge the back edges of those panels an screw the fronts for rempvability. If i didn't need access i would just nail.
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Old 09-14-2007, 06:14 PM - Thread Starter
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Boy I wish I knew about those Rotofast before purchasing the Linacoustic RC.

Anyway, the OC 703 will cover 48 sq ft per case. I need approx 64 sq. ft. So if I go that route I will have to get two cases.

Why would you do the 705 over the 703?

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Old 09-15-2007, 06:26 AM
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Quote:
Originally Posted by tradewinds View Post

ok, thanks. My SPI does not sell it for some reason. No OC stuff only JM.

I know the Janus cloth comes in 120" so I was hoping to use that.

In the end, I may need to do individual panels. BTW, how did you mount the it to the nailing strips through the cloth?

JM 814 can be a substitute for the OC703.
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