I have a 250 watt Alpine amp running a Kenwood 700 watt peak, 350 max, 175 rated 10" sub. It's rattling pretty bad when I turn it on. I can feel a little bit of air leaking out around the sides. Could that be the cause or will the sub vibrate if under powered?

 

P.S. This is in my friend's truck. Mine sounds fine.

 

You've got too many ratings on your sub... lol
peak and max are the same...
If you have a 250W alpine (assuming it's 250W in the mode you're wired up in) then you're not starving your sub for power. Especially a 175W kenwood sub.

 

Is the box pre-fab or custom built? Take the sub out, check the voice coils to make sure they are still ok, and then put the sub back in. You could take the time while the sub is out to check the box for leaks too.

That's what's coming to mind right now..

 

Stick a DMM on it and see whats you get for an OHM reading. Should get close to what the VC is (4 ohm, 2 ohm, etc)

If that checks out ok, check stuff like the dust cap, spider, etc to see if anything is starting to come unglued.

 

bad rca cords, wire grounded somewhere..........things to consider.

 

I'd second Bartak's reply, only you don't really indicate clearly if it's a mechanical noise(scratching, clunking, rattle), or an electrical induced noise(buzzing, whining). That would really clarify things for troubleshooting.

 

I think it's a mechanical noise, not something electrical. We put some foam around the speaker and it got a little better. I think we just need to seal the box up some more and it should be fine.
Thanks guys!