| Janek, if you don't mind, I would like to field that question.
Jazz Basses can hum when the volumes on each pickup are different. But they won't always hum. And considering that almost all studios are built to reduce hum, ground noises, and other spurious signals that can cause interference, it's not much of an issue most of the time. That's not to say it doesn't happen, but most studios are pretty good at rejecting noises.
Now I can't speak for our forum host here, but it's rare that I've ever done a session without both pickups on full. Most people like that sound best. However, there's a reason Sadowsky was succesful in New York by modding Fenders in the 70's. The session guys wanted dead quiet Jazz Basses because they could only take one or two basses due to transportation issues. And if they wanted to use only one pickup, they wanted to make sure that there wouldn't be any noise when they did it.
My personal opinion is that if you can only bring one bass to a session, make it a Fender Jazz or a quality copy like a Lakland or Sadowsky and either shield the hell out of it or put in noiseless pickups that look and sound as close to the stock Fender pickups as possible. |