Built box too big, how to control excursion?

[Jameson Styles]

In my early days of audiophilia, I bought a 10" driver at my local surplus store for $25. No specs on it, AT ALL, not even a real rating on impedence. However, it has amazing excursion, a 2" or so voice coil, and a big honkin 45oz or so vented magnet, and a roughbacked poly-coated cone. When I knew nothing of speakers, I was SOLD.

However, I have now learned the ways of thiele/small. I know that high excursion drivers need big boxes. So I tore this driver out of the too-small box I built for it before and built a new, bigger box for it. About 1.5 cu ft.

At first I was amazed by the performance. It was smooth, deep, and the box rumbled just enough to tame any response peaks. It was just a lovely little subwoofer, powered by a 60w plate amp. However, on higher volumes, bass drums make the woofer go beyond xmax and clip, making that kinda "poof" sound.

So I wonder, what can I do? I think I built me box too big. I've already insulated three internal sides with fiberglass, would insulating the other two help to dampen out the overly low-lows that make it overdrive, or do I need to stuff it with pieces of 2x4 to reduce internal volume? I'm open to any suggestions.

[planet10]

More damping will make the box seem bigger.

Try putting some bricks, chunks of wood, full paint cans, whatever into the box to see what happens....

I suspect your amp may be clipping thou.

dave