I'm getting a screeching sub distortion sound when trying play the dynamic sub peaks. I noticed this in the Master and Commander movie. When the volume was set to hear voices good it seems the loud cannon fight scene made the sub do this, and now I notice it happening with other movies. Can anyone tell me how to tell if the sub is blown for sure, or if it could be another cause, like amp or pre/pro malfuntion or clipping. I need to find and fix the problem, so any advise would be much appreciated.

Thanks

The manufacturer of the sub would probably be a better source of information on whatever particular model you have. It sounds like you may have damaged the driver though if it started with one incident and now happens with more movies than before.

Can you be more descriptive than "screeching"? That's not usually a description you associate with a subwoofer.

Also, to hear the dialog better, have you thought about turning up your center channel only? Almost all dialog in a modern movie is in the center channel so pushing that up may help you hear dialog without completely affecting your front soundstage.

Sorry I can't help more...