KM 256

Common name: Neumann KM 256

Production Status: Discontinued / Vintage

The Neumann 256 is a special version of the KM56 with an RF-shielded 7-pin Tuchel connector manufactured from 1961 to 1964. Powering requirements and microphone specifications are identical to the KM 56. KM is the acronym for “kleinmikrophon” meaning “little microphone”. In 1953 Georg Neumann GmbH introduced the “KM” family with the KM 53, a miniaturized pressure (omnidirectional) condenser microphone. The professional market request was for microphones offering the same quality as the U 47, M 49 and M50 with a very small size. These microphones were aimed at television broadcast and similar applications. In 1954 a newly developed 21mm cardioid capsule, the KK 54 was designed. The KM 56 microphone (1956), third in the KM series was the first switchable-pattern miniaturized microphone featuring omnidirectional, cardioid and bidirectional polar patterns. It really is an engineering masterpiece. The new dual-diaphragm capsule was obtained by coupling two KK 54 capsules back to back in a specially designed plastic holder. The KK 56 has the original 21mm diameter of the previous KK 53 and KK 54. The microphone preamplifier was also derived from the KM 53. The small barrel housing not only the Telefunken AC 701 k tube and the output transformer but also more passive components and the little rotary switch for pattern selection. Because of this high level of miniaturization, the KK 56 was an expensive item in the brand catalogue. The circuit received regular improvements during that time and moved from the original KM 56 to the KM 56c. The special “RF-proof” series is named KM 256 – KM 256c. These are easily recognizable and feature larger than 21mm RF shielded Tuchel at the connector end. Many accessories were available for KM’s such as different length capsule probes, in-line pad modules (Z 29) as well as standard, rack mount and battery-operated power supplies. The KM 56 microphone was used extensively for orchestra recordings and TV productions. It was used in “Decca Ltd. FFRR and FFSS” sessions as in some of Robert Fine’s “Living Presence” recordings and in several RCA Living Stereo productions as well as for some of “The Beatles” sessions at Abbey Road Studios. The power supply units for these RF-proof versions can be identified by the letter “h” after the standard model number such as NKMh or BB9h.