At church right now, we tend to have some issues with the bass, regardless of who is playing. There's always significant buzz if the bass volume is turned up very high, and sometimes the tone control can do it too. It really boxes us into a corner with volume and everything, as the buzz can be a real killer.

Does anyone have any general troubleshooting tips for this? The basses are not incredibly high-end, and I think the three are an Ibanez GSR something-or-other, Schecter, and Rogue (MF) 5-string. All of them but the Rogue have active electronics.