1st I only noticed this every few minutes with a tiny crackle when I hit open A, but it progressed last night to unplayable. It's a P-bass. I thought it was the pick up for the E and A string at first, but then I noticed the crackling even when I hit G or D. I also noticed that the crackling fluctuates when I press down on the pick guard near the knobs. So now my guess is that something is loose, and when I hit the string the vibrations are causing this loose connection to go crazy. What do you guys think, and do you think I can fix it with a soldering iron and some solder? Or maybe my amp is fried... 
