Neumann U 47 is a large-diaphragm condenser microphone. The original series, manufactured by Georg Neumann GmbH between 1949 and 1965, employed a tube design; the M 7 capsule was used until 1958, then superseded by the K 47.
Neumann U 47 FET was a first reissue, with a head grille similar to the original U 47 but using solid-state circuitry (discrete op-amps) and using the K 47 capsule. Intended to recapture the sound of the original U 47, enjoyed only limited success; however, the U 47 FET became well known among recording engineers as a brass and bass drum mic; it also gained great popularity among double bass players in the jazz world. It was manufactured by Neumann between 1969 and 1986, and was reissued itself in 2015.
The microphone is well known for its clear sound, with a distinct emphasis in its upper-midrange frequency response and it has been used in countless famous recordings. The original U 47 tube microphone is featured on many Frank Sinatra album covers and songs, including "I Got You Under My Skin".
Neumann U 47 is regarded as one of several all-time preferred tube recording microphones ("The Big Five"). Its desirability is based primarily on the synergy of its three sound-shaping components: capsule, tube, transformer. The U 47 used the M 7 capsule, which was similar to the capsule originally developed for the CMV 3 microphone developed in the late 1920s ("Neumann bottle"). The M 7 PVC membranes deteriorate and dry out with age, therefore in 1958 the M 7 capsule was superseded by the K 47, which had a similar acoustical design as the M 7 but used membranes made of age-resistant biaxially oriented PET film.
The U 47's circuitry was based on the Telefunken VF 14 M vacuum tube (Neumann attached the suffix "M" to VF14 tubes selected for low microphonics) and the GN8/BV8 transformer; for export to the American market, the GN8 transformer was replaced in the late 1950s with the GN8b which featured lower output. The VF 14 was a pentode made exclusively by Telefunken for Neumann until 1957; the discontinuation of the U 47 was caused primarily by the decision by Telefunken to halt production of the VF 14, and Neumann eventually depleting its stock of VF 14 tubes. To simulate the discontinued and obsolete VF 14 pentode, custom tubes and solid-state tube emulations have been manufactured specifically for the U 47 by Telefunken and others.
Beginning in 1962, Neumann offered a direct plug-in replacement kit ("AR 47") for the VF 14 featuring the Nuvistor 13 CW 4, which required minor power supply modification.
The U 48, introduced by Neumann late 1957, was identical to the U 47 except for the available polar pattern combinations (cardioid and figure of eight instead of cardioid and omnidirectional). The Beatles' producer George Martin used the U 48 extensively in the group's recordings at Abbey Road Studios, London. As successor to the U 47, Neumann introduced the U 67 in 1960.
The U 47 FET, introduced by Neumann in 1969, was less appreciated as a vocal microphone but became ubiquitous in studios as a bass drum microphone. Used on the outside of the bass drum, in conjunction with a primary bass drum microphone (which would usually be placed on the inside, or close to the inside of a bass drum or a bass drum head), it would make a complete bass drum sound.
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