What's causing violent woofer oscillations?

[espresso]

Thanks, I'll go through this. I suppose one TL074 does the trick here.

 

[5th element]

Indeed, there's no point in using a more costly op amp at all in this application. One thing to bare in mind though, is that you will need a simple buffer stage before it.

 

[head_unit]

I think your amp is clipping (due to ultra boost), and losing all control/damping over the cone. Any frequencies below the port will especially resonate.

Big bass out of such a tiny enclosure and driver is simply not possible, especially at the price point this kind of stuff sells for. Sounds like an all-around poor implementation.

Start another thread, and maybe at Audio Asylum, for sub buying recommendations. Be sure to specify it's for a computer. I don't know offhand.