I currently use a Ibanez SDGR 250 Active Bass, and just started using again a Fender 25 watt Rumble amp that I got a while ago. A crackling noise now comes from the amp both while I am playing and when I just have my bass plugged in. I switched to a new cord to see if that was the problem, but the crackling noise is still there. Could it be the battery in my bass? I've only been playing bass for a few months, and was unable to find the answer to this question on the internet.