So I recently got a new instrument, it's got 2 humbuckers, 2 volume controls and a 3 way pickup selector, but I've noticed that when I flick the switch to the neck position, and roll the neck volume all the way down, I can faintly hear the bridge pickup, and vice versa in the other position. This is especially prevalent when I'm playing with gain. With some googling I think I found that this might be called crosstalk, so I'm wondering now how to fix it. If anyone has any advice I'd greatly appreciate it, thanks!
That should not happen with a pickup selector switch. There is such a thing as "crosstalk" but not on an instrument with a selector switch, there is no way for an audio signal to pass through the air gap on a properly working switch. New instrument? If this "crosstalk" is an unacceptable problem, return the bass. Can't give any more specific advice without details on the instrument and its electronics.
Precisely how did you confirm that with the switch set to the neck pickup you are also getting signal from the bridge PUP? And what is it? Those bits of information will help with troubleshooting.
In this case I bought it used but almost new so I'm not able to return it. I think this is probably an issue from the factory because it's difficult to notice. I worked it out mainly after playing with some gain on. So I rolled the neck pickup all the way off, had the bridge pickup on, and flipped through the switch. Bridge solo and both pickups on produced the sound of the bridge pickup as expected, when I flipped to the neck position I was still getting signal through my amp, just with less gain, I double checked this by tapping the pickups with a screwdriver as well. The opposite was also true with the other pickup.
Can we see some photos of the wiring? Also, can we see a diagram of how the two pickups, two volumes, and switch are connected to each other? Is this a brand new and unmodified bass, or something old or possibly modified? Crosstalk can happen for lots of reasons. Usually it has to do with the physical layout of the wiring for the two channels.