# Standing Waves in Long Enclosures

Discussion in 'Home Theater Projects' started by Richard Little, Nov 14, 2003.

1. ### Richard Little Stunt Coordinator

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In long enclosures such as some sonitube subwoofers designs, standing waves occure in the subwoofers frequency range of 16hz to 120hz. What is the unwanted byproduct of having these standing waves inside the frequency responce range?

This site http://hyperphysics.phy-astr.gsu.edu...es/opecol.html shows a standing wave forming at about 50hz when a closed cylinder of 1.7 meters or 5.6 feet is used. I have read that a disk can place some where inside the length of the tube to break up the wave but where to put it? In the middle of the tube or at a 1/3 point.

2. ### Pete Mazz Supporting Actor

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It looks like what he's calling a closed column is actually open on one end. I always thought that a standing wave in closed enclosure happened at 1/2 wavelength dims and not 1/4.

Pete

3. ### Richard Little Stunt Coordinator

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OK, same question
In long enclosures such as some sonitube subwoofers designs, standing waves occure in the subwoofers frequency range of 16hz to 120hz. What is the unwanted byproduct of having these standing waves inside the frequency responce range?

This site http://hyperphysics.phy-astr.gsu.ed...ves/opecol.html shows a standing wave forming at about 100hz when an open cylinder (still within the normal frequency range) of 1.7 meters or 5.6 feet is used. I have read that a disk can place some where inside the length of the tube to break up the wave but where to put it? In the middle of the tube or at a 1/3 point.

Pete, you obviously have some insite on the subject. Please just answer the question at hand, or don't, instead of reinforcing the fact that I have questions…

4. ### Pete Mazz Supporting Actor

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Just trying to make sense of the sites information.....as it relates to your question.

Since sonotubes have little damping, internal standing waves should create audible distortion from the enclosure.

Not sure what you mean by a "placing a disk".

I would use stuffing at the mid point of an enclosure to absorb standing wave energy. You want the stuffing ideally at maximum particle velocity, and that would be midway.

Pete