Right front speaker problem
 

Hey everyone, I have this problem with my right front speaker. The problem is it keeps going out. I have aftermarket (Pioneer) speakers, Kenwood head unit, Sub, amps etc. Anyways, it will be on when I first turn on the stereo and then go out after a while (anywhere from a few minutes to a half hour or more). When it does this I can hear a high pitched whine that increases throughout the RPM range when I'm driving. Then, if I turn off the ignition and wait a few seconds then turn it on again it will be back on miraculously. I don't think it's a loose wire because of the behavior but I don't know. Any ideas? TIA.