I'm experiencing an odd problem. I've got 1980 Heresys hooked up to Bottlehead Paramour monoblocs and a Bottlehead Foreplay preamp. The pre and the amps are unmodified. There is normally very little hum, a little, but not much. I hadn't listened to this system lately for one reason or another. I got a chance to listen this weekend and found more hum than I'm used to. I shut everyting down and checked all the cables and tube sockets. It still hummed. I pulled the grills off the Heresys to try to get a better listen. The hum seemed to be comming mainly from the left side. I gently tapped the cone of the woofer on the left and the hum dropped down to the very low level that is normal for this system. It didn't come back during that listening session but returned the next time. Again, gently tapping on the left woofer made the abnormal hum go away.
Anyone got any ideas about what's going on here?