I have a set of speakers I picked up for a friend off of Craigslist that for some reason at higher volumes seem to what I call "reverb" through the two woofers. It goes away if you quickly turn it down then back up. I wondering if incorrect polarity could cause the problem. A better way to describe it is that the cones just push out and hold creating a continuous LF hum that grows. Any ideas? At the time I didnt think of checking the speaker wires because I have faith I connected them properly. But now Im left wondering.
(they are the type of speakers with a tweet, mid and two 8 inch woofers)