Microtech Gefell - 90 years of history and stories

The first measuring microphones

Even in the early years, Georg Neumann focused on the development and production of measuring microphones.

From 1937 to 1942 Siemens&Halske dealt with the basics of the development of condenser capsules for sound pressure meters.

Georg Neumann manufactured such transducers of the type Rel mph 9 Tz 20 (1937) and Rel mph 19 (1942) for Siemens&Halske/ S&H in special production, also called "railway capsules" or "Siemens capsules", with omnidirectional directional characteristics and an absolutely linear frequency range, designed in an aluminium capsule for a series of acoustic Siemens measuring devices.

For example, for the Siemens sound pressure meter Rel msv 5d, for mobile use, with accessory case for batteries, double headphones Ruf tph 1b and others.

Intended use: The sound pressure meter allowed in a simple way to adjust the sound pressure at of a previously calibrated measuring instrument directly in µb. A Neumann condenser microphone (30 to 10,000 Hz / pure pressure receiver) was used as the sound receiver, which was far superior to the former handheld microphones in terms of measurement accuracy (especially at low frequencies), frequency response consistency and small sound field distortion.

Another interesting Siemens offer is a Neumann condenser microphone with mains connection preamplifier.

Application: The condenser microphone was a pure pressure transducer with a range of 30 to 10000 Hz. The microphone had an almost constant transmission rate. Therefore, the microphone, which was primarily intended as a conference microphone for high-quality speech and music transmission systems, could also be used for measurement purposes, in particular for relative sound measurements, such as frequency analyses with an audio frequency spectrometer, in a measuring station for room acoustic investigations, etc. The microphone could also be used for absolute sound measurements in certain arrangements with corresponding measurement tolerances, e.g. as a control microphone in the measuring station for electroacoustic devices. In such cases, a calibrated microphone capsule was supplied.

(compare with SIEMENS catalogue new edition May 1940 "Measuring equipment for telecommunications", SIEMENS & HAISKE AG - WERNERWERK - Berlin-SIEMENSSTADT)