# DIY back box dimensions



## NickL (Jul 31, 2013)

Hi all, new member here looking for answers. 
Me and my brother in law are building a new home theater with three in-wall speakers as center, left and right channels. The new wall will be about 19" deep (as to fit the reciever and other electronics inside the wall) which means that I must use back boxes with all three speakers. The speakers are B&W CWM663 and my question is, do I build the back boxes with the same dimensions as the original B&W boxes (BB6W), or should I make them bigger? Also, I have 2.75" inch thick Isover acoustic mineral fibreglass insulation, should I tear a couple of layers off or would that thickness work in the back boxes?

Very grateful for any input!


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## Mike Edwards (Mar 10, 2011)

NickL said:


> Hi all, new member here looking for answers.
> Me and my brother in law are building a new home theater with three in-wall speakers as center, left and right channels. The new wall will be about 19" deep (as to fit the reciever and other electronics inside the wall) which means that I must use back boxes with all three speakers. The speakers are B&W CWM663 and my question is, do I build the back boxes with the same dimensions as the original B&W boxes (BB6W), or should I make them bigger? Also, I have 2.75" inch thick Isover acoustic mineral fibreglass insulation, should I tear a couple of layers off or would that thickness work in the back boxes?
> 
> Very grateful for any input!


are you converting speakers that are normally bookshelves or towers INTO in-wall speakers? if so I'd make the enclosures as identical as possible or at least sink them into the walls and just change out the baffle for something to match your wall rather than try to put components into a wall.


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## FlashJim (May 6, 2006)

I built back boxes for my surrounds recently. The speakers were designed for a wall with 2"x 4" studs on 16" centers (standard in the US). I installed them in a semi-vaulted ceiling that had rafters on 24" centers. The surrounds will be sharing the air space with my IB subwoofer, so I needed a back box.

I ended up building boxes that were 18" x 18" x 7" and screwed them into the drywall from the front. The box was fitted so there would be enough room for the speakers "dog legs" to spin around and clamp tight to the drywall. I filled them with fiberglass before installing the speakers. With the limited air space in relationship to what the speakers were designed for, I expected the speakers to lose some low end response. To my surprise, they still go pretty deep and sound great.

I don't have access to my "good" pics, but here's one I had on my phone.


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## NickL (Jul 31, 2013)

Thanks guys. I got some mdf and will make them the same size as the originals.


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