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The Neumann U 47 FET Condenser Microphone

The U47 Goes Transistor

In the four-plus decades since its original release, the Neumann U47 FET has become a legendary microphone that stands on its own from the U47. The microphone came to fruition as Neumann put an end to production of the U47 in the mid-1960s. Working to develop the same microphone using transistors. the final design of the U47 FET featured the original K47 capsule, but could better handle high sound pressure levels without affecting the resulting recording.

The Differences Between U47 FET and U47

Similar in shape, with a full-size head grille on a shorter body, attached to a swivel bracket, the U47 FET bore more than a passing resemblance to the granddaddy U47 tube condenser. However, inside was a complex labyrinthine of wire housing the newfangled Field Effect Transistor, or FET. In fact, the FET 47 is one among many in the "FET 80 Series" from Neumann, the most famous being the KM84.

The mic boasted an SPL handling of 137 dB, which could be boosted to 147 dB by employing the -10 dB pad switch, a huge advance for the time.

Vintage Neumann U47 FET condenser mic

The mic boasted an SPL handling of 137 dB, which could be boosted to 147 dB by employing the -10 dB pad switch, a huge advance for the time. There was also a bass roll-off, dropping everything below 200 Hz to compensate for the famous bass-boosting proximity effect, (a characteristic of every pressure gradient transducer).

Behind the updated U47 grille, was the same tension ring diaphragm, the K47. At the other end of the microphone, the presence of a DIN connector indicated a regular FET, while an XLR connector indicated a FETi model.

Ryan McGuire, Director of Business Development and Audio Consultant

“The Fet 47 is known for being the ultimate mic for outside a kick drum, but it's so much more than that. Many vocals are flattered by the slightly scooped and not overly bright response - it's got a tight, pure cardioid pattern too, so miking a vocalist live amongst other instruments is a strong point of the design. Try it as well on acoustic guitars, bass, and guitar cabinets - it's truly a workhorse mic with more strengths than usually given credit for - partly because it shares its namesake with one of the all-time great vocal mics. A tube U47 it is not, but it has its own set of unique qualities that make it essential to building out a world-class mic cabinet.”

Ryan McGuire, Director of Business Development and Audio Consultant

Close-up of the Neumann U47 FET brand badge

The U47 FET in The Studio

Anyone expecting that the U47 FET would impart a tonal color similar to the venerable U47 was quickly disappointed. There is really no comparing the two microphones. Yet, it was soon discovered that the large diaphragm and high SPL handling of the mic was wonderful on one particular instrument - the kick drum.

Engineers had long been wary of miking up the kick, as the explosive sound could ruin even the heartiest mic diaphragms. But the 47 FET could handle it with aplomb, and it sounded good doing it! The mic quickly became the go-to kick drum mic, a position it still holds in studios everywhere.

Don't let that sacred status fool you though, the 47 FET excels on a wide range of sources. It's also an excellent vocal mic, as it's great for cutting out bleed on a live scratch vocal and imparts its own smoky flavor to the human voice. Considering its use on the kick drum, it's not surprising that engineers love it for bass and guitar cabs too, where it's handling of high SPLs really shines. The -6 dB output switch also comes in handy in this scenario. Last, but not least, if a loud piece of brass like a trombone needs taming, the U47 FET can work wonders.

Considering its use on the kick drum, it's not surprising that engineers love it for bass and guitar cabs too, where its handling of high SPLs really shines.

Reviving The Classic FET Microphone

The bottom of the U47 FET mic

What started out as an attempt to resurrect a classic tube vocal mic with the power of a transistor ended up creating a new classic, the U47 FET. The sound of this mic is so desirable that, recently, Neumann began manufacturing them again in exquisite detail, true to the original design with hand-wired components (look for a serial number above 10000 to tell the difference). In between the thousands already in use for half a century and a new breed ready for the next century, the Neumann U47 FET has solidified its role as a crucial microphone in any recording space.

With the Neumann U47 FET back in production, it's easier than ever to bring a modern version of this classic microphone home to your studio. The microphone has also inspired a number of new mics that range in price, but still maintain similar sound qualities to the original.

Bock Audio's iFet follows the Neumann U47 FET's lead as it's capable of high SPL handling, but also features a second set of FET electronics. In "I" mode, the iFet offers a high SPL Class A package, similar to the original U47 FET. When using "V" mode, the microphone has a warmer sound that can better handle lower frequencies.

Acknowledging the shortcomings of FET technology of the 1960s, Wunder Audio began developing a new take on the U47 FET style microphone with higher standards. The resulting microphone, the CM7 FET S, features an ultra-low noise transistor with JFET technology and also employs a 1073-style mic pre transformer.

With the 47 SuperFET, Flea Microphones has taken much effort to match the sound characteristics of the tube U47, while still offering the benefits of a FET circuit such as a higher signal to noise ratio. They have certainly accomplished this feat, as the 47 SuperFET has a beautiful tone that will improve the mic locker in any size recording facility.

As a wallet-friendly pick for studios with discerning budgets, the Soundelux U195 is an affordable microphone that doesn't skimp on sound. The cardioid patterned, phantom-powered, large diaphragm FET microphone is an excellent choice for a wide range of uses from vocals to kick drum.

Coming in at only $299, the Roswell Pro Audio Mini K47 is an extremely inexpensive option for those looking to capture a little U47 FET magic. The microphone features a classic 34mm K47-style capsule and will provide engineers with a full, balanced tone without any harshness in the upper frequencies.