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post #1 of 8 Old 12-06-2017, 06:03 PM - Thread Starter
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in ceiling speakers attic insulation

Posted this in Speakers forum too .. not sure what is the better place for it ..

Planning on installing 4 in-ceiling speakers for an Atmos setup.

Above the room is the attic to which I have access. From what I see (and if I understand what I see ), it seems to have some batt insulation (pink fiberglass batts maybe .. ), in addition to blow-in insulation (like small pink snow ..) and also plastic above the sheet-rock (vapor barrier ?).

Not sure what is the best thing to do here when adding the speakers ..

1. Cover with maybe something like this

https://www.amazon.com/OEM-Systems-I...ct_top?ie=UTF8
or
https://www.parts-express.com/pro-wi...nge00s3dy0005c

and then maybe put the fiberglass batts on top

2. Just clear up the insulation and have nothing on top of the speaker, just around it

3. Anything else recommended ?

I have read about concerns with vapor barrier and air draft with in-ceiling speakers , so not sure what a good solution might be for that.

Anyone recently installed some that can share similar experience ?

Last edited by alextr75; 12-06-2017 at 06:43 PM.
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post #2 of 8 Old 12-06-2017, 08:35 PM
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If you can get to the back side of the ceiling, I would build some backer boxes out of something like MDF optionally lined in something like drywall or tile backer board and then set them on top of the speakers. Use some caulk to glue/seal them to the drywall. This pretty much creates a ceiling around the speakers. Just assuming 4 8" round speakers in the ceiling is a pretty large hole in your building envelope, and holes in the envelope will be holes for sound to flank and HVAC energy to escape. Backer boxes will also prevent the back side sound from reaching other rooms that share the same attic volume.
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post #3 of 8 Old 12-06-2017, 09:35 PM - Thread Starter
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Quote:
Originally Posted by BSHuff View Post
If you can get to the back side of the ceiling, I would build some backer boxes out of something like MDF optionally lined in something like drywall or tile backer board and then set them on top of the speakers. Use some caulk to glue/seal them to the drywall. This pretty much creates a ceiling around the speakers. Just assuming 4 8" round speakers in the ceiling is a pretty large hole in your building envelope, and holes in the envelope will be holes for sound to flank and HVAC energy to escape. Backer boxes will also prevent the back side sound from reaching other rooms that share the same attic volume.
I do have some spare MDF, which I can probably use for this. They are indeed 8" speakers, I think the actual hole is even a little bigger, something like 9 3/8. It is the Polk Audio MC80s.

I am not really sure what depth should I build the boxes, should I only make it enough so it does not touch the cone on the back, or maybe make them like a cube, so if a foot wide and long, then also a foot deep ?

I have read different opinions on this, some people advise against backer boxes given the speakers were not designed for ones, and not sure if it will negatively affect or damage the speaker, but might be the best way to prevent draft.
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post #4 of 8 Old 12-07-2017, 09:21 PM
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Quote:
Originally Posted by alextr75 View Post
I do have some spare MDF, which I can probably use for this. They are indeed 8" speakers, I think the actual hole is even a little bigger, something like 9 3/8. It is the Polk Audio MC80s.

I am not really sure what depth should I build the boxes, should I only make it enough so it does not touch the cone on the back, or maybe make them like a cube, so if a foot wide and long, then also a foot deep ?

I have read different opinions on this, some people advise against backer boxes given the speakers were not designed for ones, and not sure if it will negatively affect or damage the speaker, but might be the best way to prevent draft.

Look at my build thread for the backer boxes i built.. It will give you some idea what I did, and you can apply to your install.

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post #5 of 8 Old 12-08-2017, 04:51 PM
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Quote:
Originally Posted by alextr75 View Post
I do have some spare MDF, which I can probably use for this. They are indeed 8" speakers, I think the actual hole is even a little bigger, something like 9 3/8. It is the Polk Audio MC80s.

I am not really sure what depth should I build the boxes, should I only make it enough so it does not touch the cone on the back, or maybe make them like a cube, so if a foot wide and long, then also a foot deep ?

I have read different opinions on this, some people advise against backer boxes given the speakers were not designed for ones, and not sure if it will negatively affect or damage the speaker, but might be the best way to prevent draft.
I have Polk inwalls and in ceilings. Trust me you'll want backer boxes. I went to the actual Polk Audio site forum. I was given exact cubic inch dimensions on what to build for a backer box, for each style speaker. For your attic, you can always put putty pads/ duct seal ( cheaper) and install where your boxes mate with your attic floor...then ultimately wrap some attic insulation on top/ sides of your boxes. Hope this helps.

Thee Rock n' Roll Theatre-coming soon.
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post #6 of 8 Old 12-08-2017, 07:12 PM - Thread Starter
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Quote:
Originally Posted by 69glamboy View Post
I have Polk inwalls and in ceilings. Trust me you'll want backer boxes. I went to the actual Polk Audio site forum. I was given exact cubic inch dimensions on what to build for a backer box, for each style speaker. For your attic, you can always put putty pads/ duct seal ( cheaper) and install where your boxes mate with your attic floor...then ultimately wrap some attic insulation on top/ sides of your boxes. Hope this helps.
Thanks, I was planning to build the MDF boxes and maybe stuff some polyfill in, and that once positioned in the attic, use duct tape to seal them with the plastic sheeting / vapor barrier (the material I have on top of the sheetrock).

Once done, around and on top of the boxes, I'd put the insulation that used to be there before I added the speakers & boxes. That more or less sounds like what you suggested, though not sure about the polyfill.

Might be best to open an account and check with the Polk Audio forum to see if I get an answer about the best size and whether any polyfill is required.

The speakers I am expecting are the Polk Audio MC80,.

If you don't mind me asking which ones were yours and would you still have the information about the cubic dimension you were given ?
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post #7 of 8 Old 12-08-2017, 07:54 PM
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I'm using Polk TC60i's for in ceiling's ( back surround) Cant find my scratch notes but my backer boxes for these are 16" x 16" x 10" deep. My side surround in walls are Polk 265 LS's , I believe those boxes were 1.2 cu meters (?). If you do a search for " backer boxes " in this forum I believe my old post will show up. I actually copied the 265 LS factory boxes ( they were discontinued, but if you found them online they were going for $200.00 a piece (!) ) These had chambered inner walls/ polyfill etc. Quite extreme. But my copy cats sound pretty good. Without backer boxes your sound will travel to cyber space, into insulation etc. Remember to caulk your box seams with acoustic sealant and even your speaker cable entry hole. Its worth setting up an account on the Polk site. There are some knowledgable heavy hitters there that can assist with your speaker models. ( Polk speaker forum)

Thee Rock n' Roll Theatre-coming soon.
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post #8 of 8 Old 12-08-2017, 08:07 PM
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https://www.google.ca/search?q=polk+...5DSYZtl0jr1rM:

Not sure if this link works. Heres my side surround box, missing a small hunk of insulation in bottom left corner.

Thee Rock n' Roll Theatre-coming soon.
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