Okay, now I have a problem with the 2440 in my subwoofer. Same rattle as with 2450. Does anyone know if these 18 inch woofers have the mass controlling ring in them? I had a problem like this with my 136As in L-300s a while ago. I had to remove the dust cap and have the ring re glued. The well known speaker repair shop in So Cal recommended leaving it out. They said they tend to come loose and may bottom out on the pole piece. I left it in and have had no problem.