The U 47 was the first microphone with a switchable pick-up pattern. By manipulating the polarization voltage on the rear diaphragm the mic can achieve either a “cardiod” or an “omni” pattern. A nearly identical microphone was also made, the U 48, whose only difference was a different method of diaphragm switching which allowed for “cardiod” and “figure-8″. The U 48 can be seen in numerous photographs of John Lennon and Paul McCartney singing together on early Beatles recording sessions. Rumor has it that EMI’s Abbey Road Studios even sent some of their U 47s back to Neumann to be modified into this configuration. Far fewer of these mics were sold, and considering how rare U 47s are, U 48s are even harder to find. – See more at: http://morrisound.com/2012/11/16/neumann-u-47/#sthash.rGU9PYCQ.dpuf