Today at band practice, I was playing along and everything was fine. Then I shut my amp (Ampeg B3158) off for a few minutes. When I turned it back on, some horrible loud distorty synth-y almost noises came out when there was usually just the hum of my jazz bass. When I played, it sounded like my 8" speaker was ripped. There was this sound like sheets of paper. After playing a few songs like that, I turned it off and got some donuts. When I turned it back on, all was fine. Is there any explanation for this? Are my speakers ripped? And if they are ripped and I need new ones should I contact Ampeg, or buy some like Carvin? The Carvin 8s are rated at 200 watts, and their 15's are rated at either 400 or 600 so I don't think there would be blowing problems. Help? Thnx in advance.