A friend's Jazz Bass with Bartolini pickups and a preamp is suddenly buzzing a lot. It's a pretty high pitch buzz. It goes away when you touch the control plate and knobs, but not the strings. The strings are not grounded. Would they typically be grounded in this type of setup?
What would cause an instrument like this to suddenly start buzzing. The Bartolinis and preamp have been in it for years, supposedly without buzzing.
Unfortunately, I have little experience with active instruments and don't know the model numbers for the pickups or the preamp.