Neumann UM 57 1960s - Nickel

UM 57 - THE EVOLVING OF NEUMANN AND GEFELL Introduced in 1957, the Neumann–Gefell UM 57 represents an important development in the history of German condenser microphone engineering. Following the Second World War and the division of Germany, microphone production continued at the original Neumann manufacturing facility in Gefell, while Georg Neumann established a separate operation in West Berlin. The Gefell factory maintained the engineering traditions established during the early years of German condenser microphone development. The UM 57 was developed during a period of considerable investment in European broadcasting infrastructure, when professional studios required reliable microphones capable of operating in different acoustic environments. Its combination of the established M7 capsule, EC92 tube amplifier, and remotely selectable directional characteristics made it a versatile professional recording instrument. The UM 57 belongs to the first generation of Multipattern tube condenser microphones developed in Gefell under Neumann . OPTICAL CONDITION Grade B This coating was carefully removed during restoration, revealing the silver-grey metallic finish underneath. The original Neumann–Gefell identification badge has been preserved. The microphone presents a clean, restored appearance while retaining its historical character. TECHNICAL CONDITION Grade A — Refurbished and fully functional. With the original Neumann power supply converted to XLR output BUILD & DESIGN ​ The UM 57 employs a cylindrical metal housing containing the condenser capsule, vacuum tube amplifier, and output transformer. Its construction reflects the professional broadcasting requirements of the period, emphasizing mechanical stability, electrical reliability, and serviceability. The microphone operates through a dedicated external power supply, which provides the voltages required by the vacuum tube and condenser capsule. The external power supply also permits selection of the microphone's directional characteristics. This arrangement allows the microphone to operate in three different polar patterns without physically exchanging the capsule. THE M7 CAPSULE The UM 57 incorporates the M7, one of the most historically significant condenser capsules developed by Neumann. The M7 uses two gold-coated PVC diaphragms arranged around a central electrode assembly. Its dual-diaphragm construction allows different directional characteristics to be produced through changes in electrical polarization. The capsule design was established before the introduction of the UM 57 and was already associated with several important German studio microphones. In the UM 57, the M7 provides the acoustic foundation for the microphone's three selectable polar patterns. The capsule's acoustic behavior is determined by the interaction of diaphragm tension, acoustic resistance, capsule geometry, and polarization voltage. THE EC92 TUBE AMPLIFIER The original UM 57 uses an EC92 triode vacuum tube. The amplifier provides impedance conversion and amplification of the extremely high-impedance electrical signal generated by the condenser capsule. The amplified signal is delivered through an output transformer, producing a balanced signal suitable for professional recording equipment. The amplifier follows the engineering principles established in Gefell's earlier tube microphone systems. Its design combines a relatively simple signal path with the electrical requirements of an externally polarized condenser capsule. POLAR PATTERN CONTROL The UM 57 provides three directional characteristics. OMNIDIRECTIONAL Sensitivity to sound arriving from all directions. Suitable for recording natural acoustic environments, ensembles, and room ambience. CARDIOID Directional sensitivity with reduced pickup from behind the microphone. Suitable for individual instruments, vocals, and situations requiring greater acoustic separation. FIGURE-EIGHT Bidirectional sensitivity with strong rejection at the sides. Suitable for stereo recording techniques and applications involving two opposing sound sources. Pattern selection is achieved electrically through the microphone system's polarization circuitry. ​ POWER SUPPLY & CABLE SYSTEM The UM 57 was designed as a complete microphone system consisting of the microphone, external power supply, and dedicated connecting cable. The power supply provides the electrical operating conditions required by the vacuum tube amplifier and condenser capsule. The original connecting system uses a six-pin arrangement. Historical documentation identifies the C57 microphone cable system with NS 84 and NS 85 connectors. The external power supply and cable arrangement are integral parts of the original microphone design. This power supply was converted to a modern XLR output ​SOUND & PERFORMANCE This particular UM 57 delivers an exceptionally balanced, transparent, and detailed sound, combining the precision of a high-quality condenser…