I bought a passive/active Koa wood dynabass in 1990 or 1991 and it's time to replace the pickups. They still sound great and I continue to get comments about how good the bass sounds but I'm getting way too much hum now. I pretty much just use passive but on occasion, I need that little extra oomph from the actives. As I said, the bass still sounds great and I don't want to change the sound I get. I'm really an upright guy and don't know much about electronics so I'm looking for suggestions about what to use. Thank you in advance for your help.