I own this Ampeg BA-115 for 5 month now , and i've noticed that it produces a strange sound. I thought it was a normal sound. But 2 weeks ago , while i was practecing , this strange sound sudenly stopped. I didnt know what happened. 5 Minutes later when i started to slap , the sound got back. And now every time i turn on my amp , I have to hit it or shake it so many times to stop this anooying noise. But when i play slap and high dynamics notes , the sound immediatly gets back. And it sounds like this: sssssssssss.... AND THE SOUND IS COMING OUT OF THE TWEETER NOT FROM THE 15'. So can anyway help me please? If u know anything about tweeter's noise , or BA-115 problems please reply here.