how do I fix this...

[maylar]

I built custom 10" sub boxes for my son's Ford Ranger. The size was dictated by available space, and ended up pretty small (about .3 cu ft). At some precise volume level, the woofer breaks up and becomes nasty distortion. Below that level it's fine. I know the amp and speakers are not near their limits, so the problem has to be the box design. Back pressure? I dunno what it's called.

What options are there, besides going to 8" speakers?

Would drilling a big hole in the box allow some of the air to escape and prevent this phenomenon, or would it get worse?

Would fiber fill have any effect?

I put a lot of work into these boxes and don't wanna start from scratch again

[McCraperson]

put in some filler and see if it helps, if it doesn't, then i guess u gotta build some bigger boxes