Common name: Neumann KM 54a
Production Status: Discontinued / Vintage
KM is the acronym for “kleinmikrophon” meaning “little microphone”. The KM 54a is the first improved circuit version of the KM 54. 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 of 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. It had great performance with 25 dB / 1 kHz rejection for back-side sounds. The microphone preamplifier was almost identical to the one used in the KM 53. It was designed around the Telefunken AC 701 k tube. The output transformer and all the necessary components were housed within a very small cylinder achieving an high grade of miniaturization for the times. The aluminium diaphragm was able to withstand the high heat coming from TV lamps better than a standard synthetic film membrane (e.g. PVC). The circuit received improvements during the time resulting in a KM 54, KM 54a and KM 54c exactly as it happened for the 53 and KM 56. The special “RF – proof” series are denominated KM 254, KM 254a and KM 254c. These feature a larger RF shielded Tuchel connector, larger than the 21 mm microphone barrel and so are easy recognizable. 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 54 microphone was used extensively for both pop-rock productions and TV shows. For decades it was the microphone used by the Pope in San Pietro. Many of them are still in use today although many have had their KK 54 replaced by the later KK 64 when they were discontinued.