I've searched through TalkBass and can't readily find info on this problem. I tried! (I can't remember where I read it but others have had this same problem too.) I just bought a used G&L L-1500, year 2000 and when I turn on the preamp switch, I can hear a faint radio station. The preamp really kicks up the treble to an extreme level and when I take it down, the radio station pretty much can't be heard. The radio pick up is worse when the G&L's pickup is in parallel and less when in series. When the preamp is off and the bass is in passive mode, there is no radio noise. I noticed that there is ZERO shielding in the cavity. Nothing! Would shielding paint, copper, brass or aluminum inside the control cavity get rid of the radio noise when the preamp is on? I don't want to modify this bass (for reselling purposes) with shielding unless if it'll clear up the radio noise. Seems strange G&L didn't do any shielding! Thanks for your help.