I bought a Bartolini NTBT active preamp to switch my Warwick Corvette standard from passive to active. I took it into the shop and it's taken about two weeks before the tech could get to it, as he is the only one at the store with experience with the Bartolini preamp. Well he finally got to it, but he called me today and told me he was picking up a hum and didn't know where it was coming from. I asked him if it was possibly the room, as I've had experiences with noise in certain rooms, but he didn't think so. I think the pickups are Dynamic Correction, but I can't quite remember as it's been away for so long. I did a search and the closest thing to my problem's advice was that the dynamic correction hum was being amplified by the active preamp. I was thinking of upgrading to EMG J/J set, but am not sure if this will solve the problem, or amplify it. I'm sorry if this post is all jumbled, but I'm a little distraught as my Sansamp also crapped out recently so I have to send it to Tech 21 for service, and my band was going to try to record. AHHHHHHHHHHHHHHHHHHHHHHHHHH!