What Is the History of the Neumann U47 Microphone?

How Did the Neumann U47 Begin Its Historical Journey?

The U47’s story began in post-war Germany. Georg Neumann GmbH, founded in Berlin in 1928, relocated its factory to Thuringia during wartime bombing; that facility was later seized by East Germany and became Microtech Gefell. Rebuilding in Berlin in 1945 with financial backing from AEG Telefunken, Georg Neumann chose a fresh start, utilizing vacuum tube advancements to design a compact, high-fidelity microphone rather than reissuing pre-war models. A prototype debuted at the 1947 Berlin Radio Show (Berliner Funkausstellung).

The first commercial sale (serial number 72) occurred in December 1949. Early units bore the Telefunken logo and were often called “Tellys” because Telefunken owned 25% of Neumann and distributed the microphones. Neumann took over distribution in the 1950s, adding its own logo.

What Makes the Sound of the Neumann U47 So Unique?

The U47’s legendary status stems from a perfect synergy among three key sound-shaping components: its capsule, its tube amplifier, and its custom output transformer.

The Sound-Shaping Capsule (M7 and K47)

At its heart lies a dual-diaphragm capsule. Early models featured the M7 capsule, measuring 34mm in diameter with gold-sputtered PVC membranes. Designed in the 1930s for the CMV 3, the M7 is famous for its sweet midrange. Since PVC dries out and shrinks with age, Neumann replaced it with the K47 capsule in 1958. The K47 retained the M7’s acoustic design but used durable, age-resistant polyester (Mylar) film. Sonically, they are similar, though the K47 offers a slightly more prominent low-mid response.

The Mythical VF14 Vacuum Tube

The U47 used the Telefunken VF14M steel-jacketed pentode tube operated as a triode. The “M” suffix denoted that the tube passed strict low-noise testing. Introduced by Telefunken in 1947 specifically for Neumann, the VF14 was an expensive, specialized “special request” tube. Its unusually high heater voltage allowed the U47 to run on a single voltage supply for both the heater and anode, simplifying battery operation and long cable runs. Telefunken produced the VF14 exclusively for Neumann from 1946 to 1957. Once production ceased, Neumann depleted its remaining stock, leading to the U47’s discontinuation in 1965. In 1962, Neumann offered a Nuvistor (13CW4) replacement kit (the “AR 47”).

The Custom Output Transformer (BV08)

Apart from the first 700 units, most U47s used the custom BV08 (Bau-Vorschrift) four-chamber transformer. It balances the tube’s high impedance with the lower impedance of microphone inputs, adding subtle coloration and enabling the microphone to handle high sound pressure levels (SPL) without distortion.

How Did the Design of the U47 Evolve Over Time?

The U47’s physical body saw minor revisions. Early “long body” versions measured 240mm in length and 63mm in diameter. Toward the late 1950s, a more compact transformer/capacitor package allowed Neumann to shorten the housing by 23mm, creating the “short body” version. Internally, both contain identical electronic circuitry and sound the same. Around this time, the head basket finish changed from polished nickel to satin nickel to prevent reflections during film and TV production.

The U47’s electrical switching system achieved switchable polar patterns (cardioid and omni) by disabling the polarization voltage to the rear diaphragm of the capsule. Disconnecting the rear diaphragm in cardioid mode made the microphone’s output 5dB hotter than in omni mode, avoiding unwanted capacitance losses.

What Are the Famous Siblings and Successors of the U47?

The U47 paved the way for several landmark Neumann microphones:

• Neumann U48 (1957): Although not sonically identical to the U47,  it offered cardioid and figure-of-eight patterns. George Martin used the U48 extensively for The Beatles’ recordings at Abbey Road.
• Neumann U67 (1960): The tube successor to the U47, utilizing an EF86 tube and K67 capsule. It offered a more controlled low end and smoother high end to handle sibilant sources.
• Neumann U87 (1967): Replaced the tube with solid-state FET circuitry, becoming one of the most famous and convenient phantom-powered studio microphones in history.
• Neumann U47 FET (1969): A solid-state version using the K47 capsule. While less common for lead vocals, its high SPL handling made it iconic for kick drums, brass, and double bass. Neumann reissued it in 2014.

How Do the Historical Neumann Models Compare?

Why Does the Neumann U47 Still Matter in Modern Studios?

Inducted into the TECnology Hall of Fame in 2004, the U47 is regarded as one of the “Big Five” tube microphones of all time. It defined professional vocal capture; before its release, ribbon microphones dominated studio recording. The U47’s clarity and “larger than life” presence permanently transformed recording standards. Vintage units command prices over $20,000, with replacement VF14 tubes reaching $4,000. Highly respected boutique builders like Australia’s BeesNeez Pro Audio offer faithful modern recreations, such as the BU47 (a part-for-part remake using a BV08 transformer and EF13 tube), the Tribute 1 with an M7 capsule, and the Arabella.

Common Misunderstandings About the U47

• The “Long Body Sounds Better” Myth: Many believe long-body U47s sound superior. However, both versions use identical internal components and sound the same; differences are purely cosmetic.
• The “Telefunken Manufactured It” Myth: Early units bear a Telefunken badge, leading to the belief that Telefunken designed them. Telefunken served solely as the distributor; Neumann built every unit.
• The “Cheap Military Surplus Tube” Myth: Rumors label the VF14 as cheap military surplus. In reality, Telefunken developed this expensive, specialized tube in 1947 specifically to meet Neumann’s microphone specifications.

Summary: Why Does the Legend of the U47 Persist?

The Neumann U47 remains the undisputed king of studio microphones because of its unmatched ability to add a three-dimensional, flattering, and “larger-than-life” character to recorded sound. Decades after its discontinuation, its combination of German precision engineering, historical significance, and sonic magic ensures that it remains the ultimate benchmark against which all other recording microphones are measured.