Line 6 Spider 15 A guitar collection is actually similar to a powerful mike coil. For many years, active microphones have been wired with the voice coil attached to the principal of the microphone's transformer, and maybe not called to surface (‘floating'). The microphone's event is normally connected to the cable shield, which will be linked to the microphone amplifier's floor (see Rane's website for more discussion).
By and big, energetic microphones are extremely calm products consequently of the combination of transformer isolation and balanced, flying indication lines during, in addition to protected, humbucking coils.
Therefore why not guitars? Instruments are notoriously overwhelmed by noise. Humbucking pickups are only an incomplete (though essential!) solution. Well-known answer is always to move the guitar pickup to a healthy result, being a microphone. An identical strategy was printed this 2001 patent request like this Line 6 Spider 15?