I have a Peavey Fury IV active bass. She's really nice for a broke teenager like me, and has a beautiful finish. But whenever I change the volume level with the control on the bass while playing I get a scratching, fuzzy noise coming from my amp. It doesn't do it when I've just set it down for a second while still plugged in. I have other basses that aren't active, and they don't make this noise. I was wondering if this is something wrong with the bass, or the amp, or is it just something that happens with active basses? Thanks for your help!