The U47 was used to record the vocals on Amy Winehouse' "Frank" and "Back To Black" albums for the songs which were produced by Salaam Remi. The Neumann U47 Microphone is a vintage mic (1947) that's held in high regards by many and is definitely a collectors item. It is one of the most cloned mics in history and usually sells for as much as $10k and more on the used market (ebay). The mic comes with a proprietary power supply and cable. It was distributed by Telefunken for a short while but then Neumann took over. There are two types of U47's, tube and FET(which stands for Field Effect Transistor). The FET's (1965) were made because the original tubes were no longer available. They are both excellent microphones but different in their sonic texture. The tube U47 sounds amazing on vocals and sax. The FET U47($2000) sounds good on upright bass and kick drum (yes, kick drum). The FET 47 can also be used on vocals but I prefer the tube model. The U47 has two polar patterns, cardiod and omni-directional. Due to the design the cardiode pickup pattern provides approximately 5db hotter output. (There was also a U48 that had the figure eight pattern but I’ve never actually used one). The frequency response for both omni and cardiod are the same, 35Hz to 15KHz with a slight bump in the upper mids. There were only about 5000 U47s made.
Here's a link to a Mix Magazine article giving more detailed info on the U47.