# Too much airspace - Fill box with foam?



## stevja1 (Jan 25, 2004)

I bought a box for a Kenwood 12" sub, and it's slightly too big. I know I'm going to get flamed for this, (who buys a box that's too big?) It is a sealed box.

I was wondering if I put some foam in the box, would that be effective in both reducing airspace and muting negative sound compressions from the sub? Thanks in advance.


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## Punkrocka436 (Jul 8, 2003)

Eh, i wouldnt do it personally. Just do what you should have done in the first place and build a box


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## sr20dem0n (Mar 19, 2003)

I don't think foam would work very well, but you can use wood blocks if you want. Make sure they're held down very tightly though, you don't want those things bouncing around inside your box. Why don't you try using it for now though? I like having larger than spec boxes personally, it raises the efficiency and low end extension.


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## wickedsr20 (Aug 8, 2002)

sr20dem0n said:


> I don't think foam would work very well, but you can use wood blocks if you want. Make sure they're held down very tightly though, you don't want those things bouncing around inside your box. Why don't you try using it for now though? I like having larger than spec boxes personally, it raises the efficiency and low end extension.


It also lowers power handling capability due to the extra low end extension.
Be careful with your gain control depending on how much power you're running or going to run. Foam or wood blocks will accomplish your goal, but just make sure to secure them well (I like liquid nails) to prevent unwanted movement inside the box. Of course, there's always the above recommended build a box to spec for the sub of choice.


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## stevja1 (Jan 25, 2004)

Crud. This is a little worse than I thought. I think I will try it out the way it is for starters. What about adding a PVC port or something? There is room. I've got a bunch of formulas for determining how the port will work. Does the box need to be extra big for that to work, or could you just build a spec sealed box and port it later? While I'm at it, what is a good bass range to tune a ported box to if I want to listen to various types of music?

I know these are super newbie questions and I really appreciate your patience and willingness to help.


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## sr20dem0n (Mar 19, 2003)

optimal ported boxes generally require a larger internal volume than optimal sealed boxes, plus you have the bigass port which takes up even more volume (the port doesn't count as part of the internal volume). If you had a sealed box that was larger than the recommendations, then you could probably add an external port and have it work well as a ported box, but then you have a couple feet of pvc outside your box just kinda hanging out.

As for the tuning frequency, I would shoot for 30-32hz if you listen to a wide variety of music.


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