I have a Carvin Pro Bass 300. its a combo amp with 300W to the head and 400W to the cabinet part. a 15" speaker in it. the problem is when i turn up past like a 7 on the master volume and a 7 on the bass volume the sound that comes out starts to buzz, sounding like a tear in the speaker. ive checked the speaker and its fine with no tears or anything. i want to use my footswitch to volume boost it without getting the buzz. it also has a tweeter switch from full to cut on the back of the cabinet part.