Should I build a box to enclose my inwall speakers?

In wall speakers and in ceiling speakers typically DO NOT need to have boxes built or spaces constricted.

These types of speakers are designed with American homes in mind. That means that the makers of these speakers KNOW that your house uses 2 x 4 studs, that our standard stud placement is 16″ on center apart (14 1/2″ of space in between studs), our walls are at least 8 feet high and our ceiling spaces are either attics or joist type structure in between floors.

That means our walls have greater than 3 cubic feet of airspace and ceiling spaces even more than that.

So if I was a maker of speakers, I would make dang sure that my speakers sound good in those spaces without any modification. And that’s exactly what they do. Most all in wall and in ceiling speakers are “Infinite Baffle” design.
In true infinite baffle designs, the front wave output of the woofer is separated from the rear wave output of the woofer with the air mass behind the woofer does not assist the mechanical operation of the woofer.

When you constrict an infinite baffle design’s airspace behind, you basically squeeze the speaker from behind and limit the movement of the woofer (the larger speaker on the plate) and that lowers the amount of bass (low sounds) coming from the woofer.
Think of it this way, say you have a glass of water and you are sipping it from a straw. If you place the straw in the free water and suck, you get a nice full stream of water. Now instead of placing it in the water directly, you keep a little water in the straw but put your finger over the other end…try sucking now…what happens? The water can’t move to your mouth and the straw collapses.

So when you ask yourself, should I build a box?  RELAX! We’ve already thought about how they are going to be installed…AND THEY’LL SOUND GREAT!

21 Comments

  • Charles says:

    Not for nothing but in the majority of south Florida homes built since the 90’s there is no such thing as 2×4 wood studs. Aluminum studs have been used since then and I am surprised the rest of the country has not caught on, although building design is not my forte. Anyway, the aluminum studs are “hollow” as they are only three sided, increasing the amount of air inside of the walls. Have you ever accounted for this?

  • Matt Adams says:

    What about walls that have insulation in them? In my basement, I have a 2×4 partition wall that will have my TV with the left, right and center channel speakers installed in it. On the opposite side of the wall is a bathroom. I intend to have the interior walls (including this one) insulated with rock wool soundproofing. If I am reading the above article correctly, the space behind the speakers is what matters the most, so I can insulate up to the speakers and above them in each stud bay, but not behind the speakers. Is this correct or does the whole bay need to be open?

    The “3 cubic feet of airspace” part confuses me. If I leave the whole bay open or even if I do not insulate behind the speakers, I am concerned about then sounds of the TV room entering the bathroom (and echoing around the room and out into the hallway etc…) and/or sounds from the bathroom entering the TV room. Are there any speakers designed to be installed in a wall with insulation? What if this was an exterior wall and insulation was required ? I have some time to decide what to do as I am just starting to install the insulation.

    Thanks,

    • Brian Kruse says:

      Matt, The insulation doesn’t count for the airspace volume. It’s not affecting the “pressure” so to speak of the airspace.

      I use this analogy sometimes: Think of drinking water through a straw in “free water”. When you suck on the straw, water flows up the straw unrestricted. Now if you capture some water in the straw and put your finger over the straw’s opening and try to suck that water up the straw, what happens? Nothing, no movement of the water. I think ice in the water is like the insulation in this example.

      A woofer (the one that makes the low sounds), needs to move out and back in to create the acoustic waves that we hear. So you don’t want anything to inhibit the airflow of a free air (infinite baffle) speaker. Insulation isn’t a problem.

  • Rob says:

    This all makes sense. What happens though if the wall is using 2×8 studs. Should I think about trying to cut down on that space?

  • Mike says:

    what are your thoughts about the long term effects of heat, cold and moisture on the speaker itself ? we have open back speakers in the ceiling and I can not believe they do a very good job of insulating the house from the weather. our speakers located with a lot of open attic space behind them sound completely different than the ones will less open space.

    • Brian Kruse says:

      Non-issue. Unless your speakers are paper cones or you live in Hawaii (where they have insects that like to eat butyl rubber (the surrounds of speakers)), there are thousands of installations everywhere that are installed in the manner that you speak.

      Enjoy your music.

  • Chris Gordon says:

    Can anyone direct me to a “best of” review of in wall speakers? Can’t really find any decent reviews.

  • Somnath says:

    Is it better to put a back cover for Ceiling speakers like the one in link below? I am putting my ceiling speakers in the ceiling where there is not much clearance ( only about 7″ ) and I think having this back cover may help avoid the speaker pushing against the existing insulation and damaging the speaker or causing any other issues.

    http://www.amazon.com/OEM-Systems-ISF-147-Ceiling-Protective/dp/B000PELN0C

  • Curt says:

    What about isolating sound from an adjoining room?

  • Roman says:

    Hi brian, we will be installing some of your speakers in a knee wall in the attic and the walls are only 4 feet tall… there is no back on the knee wall just open to the attic cavity… is this a problem and can there be something done to limit sound going into the rest of the house through the back of the speaker/wall? thank you for any information..

  • Jeff says:

    What if I bought an in-wall speaker, but found out that because of the wall design, I can’t really mount it there. So, I want to build a box to hold the in-wall speaker so I can sit it on a shelf. Any suggestions?

    • Brian Kruse says:

      I had some success with building a backless box and then putting a bath towel over the back. Obviously you’d want to use something that worked cosmetically for a living home.
      I had built these boxes to demonstrate them to dealers in their stores.

  • Dereck says:

    Hi Brian,
    I will soon be installing speakers in my drop ceiling and around on wall TV. My home is made of concrete. For the wall I plan to put a drywall pop out of about 4-5in likely from the ground to the 9ft dropped ceiling. I’m wondering if I need to do anything about the fact that its concrete in back?

    For the ceiling, I am installing open ended multi level overlapping drop ceiling like this in various heights throughout the room (side view):
    | | | |
    | | _ | | _
    _ | | |_______________|
    |___________________|

    Hopefully, that showed up straight. ^ Will I need to do anything special with speakers going in that space? Even an in ceiling subwoofer?

    I have a feeling you’re going to say infinite baffle design, but I want to be sure 🙂

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