Just had an Eminence Private Jack loaded into my Fender Musicmaster combo. Everything seems to be working as it should but, now there is a high-pitched humming sound that is present. Gets louder as the amp is turned up, is present even with the guitar unplugged. Could a cold solder joint on the speaker terminal be the culprit? Or am I looking for something else? Also, the 50w Private Jack seems to be breaking up a little more than the 20w alnico organ speaker I just removed, that doesn't seem kosher to me.