Hi, I have a setup that has worked fine for a number of years, (3 or 4) but all of the sudden I am experiencing a certain problem and I really don't know the cause or the solution. Any help is much appreciated. Here's the problem, everything works fine for about 15-20 minutes but after that my right door speaker starts bumping as if the song has a ton of midbass (on songs that don't), but if I turn the volume all the way down (to zero) it still bumps. I have 3-way Alpine components in the front, the 1" and 4" are in kick panels and the 6.5" are in the doors. It appears to only be the right mid door speaker doing this. I have to shut my whole head unit off to stop the noise. It seems to work normal if I leave the head unit off for 10-15 minutes but will quickly revert back to the problem. I suspect it is the amp powering my components, but again I am ignorant when it comes to this stuff. Anyone ever hear of this and if so, what should I do?