Yamaha Classical Guitar A best guitar pickup is essentially similar to a vibrant mike coil. For decades, energetic microphones have been wired with the voice coil attached with the principal of the microphone's transformer, and not called to ground (‘floating'). The microphone's case is typically connected to the cable shield, that will be linked to the microphone amplifier's surface (see Rane's website for more discussion).
By and large, energetic microphones are very quiet products consequently of the mix of transformer isolation and balanced, hanging sign lines throughout, in addition to guarded, humbucking coils.
Therefore why not guitars? Instruments are notoriously overwhelmed by noise. Humbucking pickups are only a partial (though important!) solution. The most obvious option is always to float the guitar pickup to a healthy output, just like a microphone. An identical strategy was published that 2001 patent application like this Yamaha Classical Guitar?