[konut]

I have this old UFW-12 that does not work. Is it possible to put blocks of styrofoam(or some other substance) inside to lessen the volume for a different 12" woofer? Would the woofer "see" it, or still "see" the total volume of the box? That would be a more attractive option than cutting a hole for a 15" woofer.

[mcgsxr]

You could insert pieces of wood to “shrink” the effective size of the box.  I’ve done that with car subs before. 

[Doublej]

Why does a subwoofer box with a 12 inch driver need to be reduced to put in a different 12 inch driver? Couldn't you find one spec'd for the same size box?

[konut]

Why does a subwoofer box with a 12 inch driver need to be reduced to put in a different 12 inch driver? Couldn't you find one spec'd for the same size box?

That would be quite lucky! The 12s I'm considering call for a smaller box for optimal loading.

[konut]

You could insert pieces of wood to “shrink” the effective size of the box.  I’ve done that with car subs before.

Thanks! The reason I suggested Styrofoam is for weight considerations as the box is quite heavy. Does the density of the "filler" enter into the equation? Hmmm?

[mcgsxr]

I have read of expanded polystyrene being used.  Unclear if actual styrofoam has the density. 

[poseidonsvoice]

As I remember, the Rocket UFW-12 was a sealed sub. You may have to do nothing in all honesty. I would first implement the new 12 inch, make measurements, before adding wood blocks to reduce the acoustic volume. Sealed subs are highly forgiving.

A larger box gives you a lower Qtc and deeper bass extension (lower F6 and F10) than a smaller box. It may sound tighter/cleaner, but that strongly depends on room placement and quality of the woofer you are replacing it with.

If it were me, I would do nothing and just replace the woofer.

If it’s ported, ignore the above, it will need a redesign.

Best,
Anand.

[konut]

Thanks for all the responses.