Jimmy Page Acoustic A guitar pickup is essentially much like a powerful mike coil. For decades, active microphones have now been wired with the voice coil attached to the principal of the microphone's transformer, and not recommended to soil (‘floating'). The microphone's case is usually attached to the wire shield, that will be connected to the microphone amplifier's surface (see Rane's website for more discussion).
By and large, dynamic microphones are very quiet units consequently of the combination of transformer isolation and healthy, flying sign lines through the duration of, in addition to shielded, humbucking coils.
So you will want to guitars? Instruments are notoriously plagued by noise. Humbucking pickups are only an incomplete (though crucial!) solution. Well-known answer is to float your guitar pickup to a balanced result, being a microphone. A similar idea was published that 2001 patent application like this Jimmy Page Acoustic?