We got a new sound system at church and now I'm going direct. Since I'm loud in the mix now, you can really hear the hum if I'm not touching the strings or if I turn the volume down at all. The sound man thinks it's a grounding issue, but every single coil bass I've had has done this. Is there any way to get rid of the hum with out changing pups? The bass is a Carvin sb5000.