Vintage: Neumann U 47

It’s without a doubt the most famous microphone in history, but just what makes this 1940s classic so special? Mike Willox reveals its secrets…

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The ubiquitous photos of Frank Sinatra recording at Capitol Studios after World War II helped to create the iconic image of the man who would go on to become the most famous singer in the world. The other star of those images was the microphone that ‘Ol’ Blue Eyes’ was singing into: the Neumann U 47. Look at any jazz record sleeve from the 50s onwards and the chances are that if there’s a microphone in the picture, it’s a U 47.

Georg Neumann founded his Berlin-based company in 1928 with his then-partner Erich Rickmann. Their developments were not limited to the manufacture of microphones, though – as well as designing direct-driven disc-cutting machines, Neumann is credited with the development of the first gas-tight nickel cadmium battery, of which the modern version powers everything from Flash memory to hearing aids.

It was this prodigious inventiveness that led Neumann to produce the first mass-produced condenser microphone, the CMV 3 or ‘Neumann Bottle’. This had interchangeable heads for different polarities and it was off the back of this incredibly successful mic – built to the exacting standards of German State radio – that the U 47 was born.

Developed in 1947, the U 47 was the first ever switchable-pattern (cardioid or omnidirectional) condenser microphone and took the world – especially the US – by storm. The U 47’s double-diaphragm M7 capsule had two back-to-back cardioid capsules and enabled both diaphragms to be polarised with the same voltage or neutralised with respect to the centre electrode, enabling the two cardioid capsules to create an omni field. This technology paved the way for the plethora of high-quality multi-pattern mics that are available today. Neumann later produced the U 48, which is essentially the same as the U 47 except that it produced a figure-8 pattern instead of an omni one.

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The ribbon mics that were in use by the major studios of the time just didn’t stand up to the big sound of the U 47 with its Telefunken VF-14 pentode vacuum tube. Along with the M7 capsule, it’s without a doubt that this valve lies at the heart of the U 47 legacy. Telefunken originally produced the steel-covered tube for the German army’s field radios in World War II, but it was Georg Neumann who gave this vacuum wonder a second life. Another characteristic of the Neumann was a lift in the upper-mids which, when used on a vocalist, enabled the microphone to rise above the high frequencies of an orchestra’s string section in a way that other mics couldn’t.

Nick Robbins, of Soundmastering, who’s used the U 47 to record Van Morrison, Shane MacGowan and Morrissey among many others, says: “The secret behind the U 47’s sound is the Telefunken tube, it gives [it] a big, fat, open sound and a wonderful smoothness.”

The microphone was adopted by every corner of the recording industry. Mercury Records utilised it as part of the Living Presence series (which heralded the general use of stereo recording for orchestral works) and it was used by almost every renowned recording artist at some time or another during the 50s. George Martin famously used one on nearly everything on The Beatles’ Rubber Soul album, while Nat King Cole and Ella Fitzgerald were also big fans of the new Neumann valve sound, using U 47s exclusively.

End of an Era
Unfortunately, however good the VF-14 tube may have been, Neumann was the only customer for it – by the late 1950s Telefunken had ceased its production. Neumann replaced the original tube with a 13CW4 Nuvistor, which people generally agree does not have the same sound quality as the Telefunken. The Holy Grail for collectors has always been the first U 47s (these originally bore the Telefunken brand in the US due to distribution issues) and a second-hand one with the VF-14 pentode vacuum tube can set you back up to £6,500, while a single, new old-stock VF-14 tube on its own can go for nearly £1,300…

By the early 1960s, the manufacture of tube mics was largely being replaced by FET (Field Effect Transistor) technology and Neumann produced its first transistor mic, the KTM 1965, in 1965. It wasn’t long before the U 47 had its final major overhaul, and these days the FET version is almost as desirable as the original valve model.

With the explosion of lookalike microphones now being produced around the world, the U 47 continues to live on in studios that are not lucky (or wealthy) enough to own one of the original Neumanns. It’s possible to purchase a valve mic based on Georg Neumann’s first switchable condenser design for as little as £500 – but there’s a reason why the original still holds its place in recording history.

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