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Subwoofer inside cabinet

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Subwoofer inside cabinet

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I am designing a cabinet that will be custom built to hold my home theater gear.  We have an older Polk subwoofer (non-powered) with a sizable footprint.  I don't have the exact measurements, but estimate it at 12" x 18".  My cabinet will be big enough to hold the subwoofer, but I am concerned about vibration.  If I put a subwoofer in a wood cabinet (real wood secured to the wall) would there likely be significant vibration?  How is this typically handled when the components are inside cabinetry?  I used to hide it behind my entertainment center, but I won't have that huge monolith once this project is complete.

Please give me suggestions on the subwoofer, or provide some assurance that it will function OK inside the cabinet.  Thanks for your help!

Verified Answer
  • Putting a sub inside a cabinet presents some problems. While bass is often referred to as being "non-directional", which is true for the most part, subwoofers are very room/position dependant. Moving a sub nearer a vertical wall reinforces the low frequencies, increasing the perceived output. Putting a sub in a corner redoubles the effect. By contrast, moving a sub away from adjacent walls "tightens" the bass response. So, suwoofer placement can be a delicate balancing act that can take considerable time and effort to yield the best results.

    Installing a sub in a cabinet (putting the box in a box) can yield acceptable results if the cabinet designed correctly and the right subwoofer is chosen. Since you already have your subwoofer (and, I assume, your cabinet design) it is going to be a bit of a crap shoot. There are a few things you can do to increase the likelihood of an acceptable result, however.

    Make sure the sub sits directly on the floor of the room. In other words, leave the floor out of the part of the cabinet that will house the sub. Doing so will help minimize vibration of the cabinet (you will be chasing vibrations, subs vibrate, that's what they do).

    Avoid movable shelving. It tends to resonate, along with everything you place on it. The entertainment cabinet shelves will not be the place to display your wife's Baccarat crystal, if you know what  I mean. If you do plan to display vases or some such things in the cabinet, Velcro is your friend.

    If you use built in lighting in the cabinet, take the time to dampen vibrations during the build process. Light fixtures are notorious noise makers.

    Cross over the sub at the lowest frequency possible considering the frequency response of your satellites and sub. The lower the crossover point, the less likely the subwoofer will hit a resonant frequency in the cabinet.

    Use good hinges (euro-style concealed hinges work the best in my experience) and tight mechanical latches (more than one on large doors) and avoid using a hinged door on the subwoofer enclosure.

    Sealed, front-firing subs tend to work better inside cabinets than down firing and/or ported subs (unless the port is on the front as well). If you have a front firing sub, you can try building up the inside of the cabinet enclosure to within about an inch or so of the subwoofer box and sealing the gap with dense foam pipe insulation (the round black stuff) or garage door seal.

    You say the subwoofer is non-powered. If it is a true subwoofer (i.e. not part of a sub/sat combo) that crosses over below about 80Hz, see if there is an alternative location for it somewhere else in the room.

    Good luck.

     

         RESIma

All Replies
  • Putting a sub inside a cabinet presents some problems. While bass is often referred to as being "non-directional", which is true for the most part, subwoofers are very room/position dependant. Moving a sub nearer a vertical wall reinforces the low frequencies, increasing the perceived output. Putting a sub in a corner redoubles the effect. By contrast, moving a sub away from adjacent walls "tightens" the bass response. So, suwoofer placement can be a delicate balancing act that can take considerable time and effort to yield the best results.

    Installing a sub in a cabinet (putting the box in a box) can yield acceptable results if the cabinet designed correctly and the right subwoofer is chosen. Since you already have your subwoofer (and, I assume, your cabinet design) it is going to be a bit of a crap shoot. There are a few things you can do to increase the likelihood of an acceptable result, however.

    Make sure the sub sits directly on the floor of the room. In other words, leave the floor out of the part of the cabinet that will house the sub. Doing so will help minimize vibration of the cabinet (you will be chasing vibrations, subs vibrate, that's what they do).

    Avoid movable shelving. It tends to resonate, along with everything you place on it. The entertainment cabinet shelves will not be the place to display your wife's Baccarat crystal, if you know what  I mean. If you do plan to display vases or some such things in the cabinet, Velcro is your friend.

    If you use built in lighting in the cabinet, take the time to dampen vibrations during the build process. Light fixtures are notorious noise makers.

    Cross over the sub at the lowest frequency possible considering the frequency response of your satellites and sub. The lower the crossover point, the less likely the subwoofer will hit a resonant frequency in the cabinet.

    Use good hinges (euro-style concealed hinges work the best in my experience) and tight mechanical latches (more than one on large doors) and avoid using a hinged door on the subwoofer enclosure.

    Sealed, front-firing subs tend to work better inside cabinets than down firing and/or ported subs (unless the port is on the front as well). If you have a front firing sub, you can try building up the inside of the cabinet enclosure to within about an inch or so of the subwoofer box and sealing the gap with dense foam pipe insulation (the round black stuff) or garage door seal.

    You say the subwoofer is non-powered. If it is a true subwoofer (i.e. not part of a sub/sat combo) that crosses over below about 80Hz, see if there is an alternative location for it somewhere else in the room.

    Good luck.

     

         RESIma