I'm going to call my amp guy but wondered if y'all have any suspicions as to what's causing a weird noise coming out of my Fender MusicMaster bass amp (6V6 version with Red Fang alnico 12" speaker). When I play the low E, especially an open E or G, third fret, there is a weird thumping sound that will sound two or three times after I hit the note. I thought maybe a loose speaker or loose baffle but I don't think that's it after checking. Also made sure the tubes were snug in their sockets, but it sounds different from tube rattle. My biggest suspicion is that the speaker is blown, but it otherwise sounds OK and has good output. Like I say, I'll be bringing it into my amp dude for trouble shooting, anyway, but it's a new one for me.