1/2" or 3/4" MDF for atmos speaker boxes?? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 07-10-2017, 11:18 AM - Thread Starter
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1/2" or 3/4" MDF for atmos speaker boxes??

Going to build 4 atmos speaker boxes next couple days and wondering if 1/2" MDF will be suffice or should I still use 3/4" MDF? The boxes will sit between the ceiling joists on top of the plywood followed by a layer of drywall with green glue sandwiched between.

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post #2 of 9 Old 07-10-2017, 11:27 AM
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Thicker the better but I couldn't imagine a big difference between them. I used 1/2" MDF for my backer boxes since the sheets aren't as heavy (no help loading/unloading). If you have pieces lying around or help then go 3/4".

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post #3 of 9 Old 07-10-2017, 11:30 AM - Thread Starter
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I could probably go ahead and do 3/4" for the speaker boxes, however I'll be ok with 1/2" MDF for my soffit's, right? The soffit will hold the ac duct and lights, no speakers...or should that also be 3/4"?

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post #4 of 9 Old 07-10-2017, 12:43 PM
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best practice is a two layer box with Green Glue between layers. Start with a Minimum of 3/4 MDF and decide if you think the location and your goals deserves more layers.
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post #5 of 9 Old 07-10-2017, 01:12 PM
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Quote:
Originally Posted by mpjmeyer View Post
I could probably go ahead and do 3/4" for the speaker boxes, however I'll be ok with 1/2" MDF for my soffit's, right? The soffit will hold the ac duct and lights, no speakers...or should that also be 3/4"?
Really depends on if you're doing pre or post drywall soffits. Post-drywall you can just throw 1/2" drywall on the soffits and be done (unless you have some really noisy ducts). Pre-drywall you'll need to treat the soffits like any other stud wall with clips/channel, DD and GG. I ran dedicated channels for my soffits and then put them up after drywall using 3 1/2" deck screws. Ran 2 returns, 2 supplies (all flex vent) and 6 can lights, no backer boxes needed but I did stuff insulation in them to prevent reverberation.

Audio: Denon X3300W / Outlaw 7140
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post #6 of 9 Old 07-10-2017, 01:54 PM - Thread Starter
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I plan on building a room inside a room first, then build the soffits. Probably just use 1/2" MDF for the soffits for the extra durability and bass dampening. The original plan was to use plywood then drywall which would have been a tight fit with the door opening and media rack so if I only use 1/2" MDF, that helps a little. I'll take every bit of space I can get. As far as the speaker boxes go, I'll use 3/4" MDF and see how that works for what I need

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post #7 of 9 Old 07-12-2017, 06:03 PM
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Your backer boxes should have at least as much mass as the holes you are cutting out. That probably means that you want 3/4". With speaker boxes, stiffer is always better. Another reason to use 3/4". 3/4" also gives you more area to screw into for anything that you screw into the end of the panels. I can't think of any good reasons not to use 3/4" over 1/2"
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post #8 of 9 Old 07-17-2017, 07:47 AM
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I used this when I built mine. Damn things were heavy.

5/8" Drywall / Green Glue / 1/2" Plywood / Green Glue / 5/8" Drywall / Acoustical Caulk
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post #9 of 9 Old 07-17-2017, 09:48 AM
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Quote:
Originally Posted by Spyderturbo007 View Post
I used this when I built mine. Damn things were heavy.

5/8" Drywall / Green Glue / 1/2" Plywood / Green Glue / 5/8" Drywall / Acoustical Caulk
Exactly as they should be!!!
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