recordinghacks

OmnidirectionalCardioidNeumann U 47

  discontinued Multi-Pattern Condenser Tube Microphone

Neumann U 47

Description

The original “U 47,” invented in 1947, was the first switchable pattern condenser microphone. Its impact, especially in America, was such that the dominance of RCA’s ribbon microphone as the studio standard was eclipsed.

The U 47 could produce either a Cardioid or Omnidirectional pickup pattern. The pattern switch was located on the microphone body, and worked by controlling (disabling) the polarization voltage of the rear diaphragm.

(The U 48 was a U 47 that provided either Cardioid or Figure-of-8 patterns.)

The U-47 did not maintain equal output levels across patterns. This is a characteristic that Neumann engineers sought to improve in later mics, such as the M 49. The U-47’s output was 5dB hotter in Cardioid mode than in Omni, because the capsule’s rear diaphragm was simply disconnected in Cardioid mode, avoiding the capacitance losses of having it in the circuit. See the history of the M49 for more information.

The original U47 employed a VF14 tube, which would become hard to find within a few years, leading to changes to the U47 design as well as the introduction of the U47fet, a FET condenser intended to sound the same as its tube-designed sibling.

Early U47 (and U48) mics contained Neumann’s M7 capsule, in which the brass backplate was covered with a thin PVC diaphragm. PVC ages poorly, and as early as 1958 the Neumann factory was using the M7’s successor, a capsule known as the K47/49, which used a metallized polyester diaphragm.

The K47 capsule used a single, shared backplate, which caused tensioning challenges, in that both diaphragms would have to be tuned identically to produce balanced Figure-of-8 or Omni patterns.

In the original German-language Neumann documentation for the U47 and similar mics, the term “Niere” — literally “kidney” — is used to denote the Cardioid pattern. The term “Kugel,” which translates to “ball,” indicates Omnidirectional.

Bill Bradley

There were about 5000 [U-47s] made, about 3200 long bodies and the rest short. People say it’s gotta be a long body to be any good. False. They’re exactly the same microphone inside.

The mic went through three revisions. They started off with a very large transformer/capacitor package. If you pull the covers off you won’t believe; they’re packed. There’s no room for anything in there. If you take exactly the same mic that’s five or six years younger, take the shell off — you’ll wonder where the mic went.

The Neumann U 47 is also known as: U47.

The mic was released in 1947.

Specifications

Pickup Patterns Pads & Filters
Omnidirectional (14 mV/Pa; 35 - 15,000 Hz)
Cardioid (25 mV/Pa; 35 - 15,000 Hz)
Capsule Dimensions Impedance SPL/Noise
Diameter n/a
 200 Ohms (Low)
Weight Length Max Diameter Interface(s)
800g (28.22oz) 240mm (9.45'') 63mm (2.48'')
  • 3-pin XLR male (1)
Power Specifications
  • Includes tube power supply

Did we get anything wrong on this page?Please let us know!