Ibanez Gio Bass Guitar A guitar pickup is basically just like a vibrant microphone coil. For decades, vibrant microphones have now been wired with the voice coil attached with the principal of the microphone's transformer, and maybe not called to ground (‘floating'). The microphone's situation is normally linked to the cable shield, which can be connected to the mike amplifier's ground (see Rane's site for more discussion).
By and large, dynamic microphones are very quiet products consequently of the combination of transformer isolation and healthy, flying sign lines for the duration of, along with shielded, humbucking coils.
So why don't you instruments? Instruments are notoriously overwhelmed by noise. Humbucking pickups are only an incomplete (though crucial!) solution. Well-known alternative is to float practicing the guitar pickup to a healthy result, just like a microphone. A similar idea was printed this 2001 patent application like this Ibanez Gio Bass Guitar?