grounding problem

Discussion in 'Pickups & Electronics [BG]' started by Andy Daventry, Apr 12, 2001.

  1. I have a problem.

    On my MB2I have both a piezo and magnetic pickups. The piezo is a Fishman acoustic matrix running through its own preamp, gounded to the cavity shielding. The mags are DiMarzio Ultrajazz, wired up in classic passive J format. The systems are separate, with a miniswitch to switch between them. I never use them together and, indeed, can't.

    The miniswitch is a 2 position on/on, with the live wires from the preamp and the passive pickups going to the respective pins, with the mid pins then running to the output jack.

    The cavity is well shielded. My problem is that I get a hell of an RF buzz on the Ultrajazz pups. Not 50 cycle hum (they are humbuckers) but the RF buzz you get from monitors, fluorescent tubes and so on.

    Ths buzz is much louder than you normally get on Ultrajazz pups, and I wonder if it is to do with the fact I have the two systems grounding to the same place. Should I isolate the systems completely, by switching between the grounds as well as the live wires? Or what else could it be?