I’ve got a Squier Affinity J Bass, and I think I’ve reasoned out what the three knobs do… The one closest to the neck adjusts the volume of the neck pickup, the middle one adjusts the bridge pickup (I’m guessing) which would leave the last one to be the tone knob? Anyway, that small knob introduces a crazy amount of noise when it gets turned on. If it’s all the way off there is virtually no noise from either pickup but the higher you turn the tone knob, the more scratchy stereotypical “I’m going through a tunnel, the connection is getting cut” noise you hear.
Is this typical? Is there an electrical wiring issue? I took off the little metal plate to take a peek behind it and it doesn’t seem like it’s corroded and the soldering all looks okay to me. I didn’t unstring it and take the pickups out or anything as I don’t really know anything about stringing a bass or adjusting pickup height.
Honestly I don’t really have a good enough ear to know where I would like to set the tone knob for any given song so I can just practice with it off, but is this something I can fix?