Neumann & Co. Gefell UM57

The legendary microphone company Georg Neumann and Co. was founded by Neumann and Erich Rickmann in 1928, in Berlin, Germany and the business produced high quality cutting lathes as well as their first microphone, the CMV3 bottle microphone., which consisted of a large body containing the high impedance tube amplifier circuit and transformer. In 1932 the CMV3 was updated to use interchangeable lollipop style heads with different patterns.

Production continued in Berlin through to 1943, when the Neumann factory was damaged by allied bombing and the company relocated to the small town of Gefell. After World War II, Gefell was in the area of eastern Germany controlled by Russia, and later the Soviet Union, who eventually took over and nationalised the factory. Georg Neumann resumed manufacturing in the Western part of Berlin with a new company called Georg Neumann GmbH, which is the company we know today as Neumann. These events led to the farcical and confusing situation of having two separate companies selling microphones with the Neumann name. For clarification we will refer to the East German company "Neumann & Co. Gefell." After the reunification of Germany, the former East Germany company became Mikrotech Gefell. 

The UM57 was manufactured by Neumann & Co. Gefell. from 1957 onwards and was their first true multi-pattern microphone. It features an M7 capsule with a PVC diaphragm on each side. The UM57 used the same tube (EC92) and a similar circuit to its predecessors, the CMV 551 and CMV 563. However, the power supply for the new UM57 microphone includes a switch with sends different voltages to the rear diaphragm, which allows the user to remotely select the pickup pattern from cardioid, omnidirectional or figure of 8, without the chore of having to physically change the head of the microphone.

Click here to see the circuit and components for the UM57.

And click here for the circuit for its N57 power supply.

Translated from the manufacturer's brochure:

The UM 57 microphone is a high-quality and universally applicable condenser microphone with switchable polar patterns. Omnidirectional, cardioid, and figure-eight patterns can be selected via remote control. Switching between patterns is done using a rotary knob on the accompanying power supply unit. Changing the polar pattern allows for optimal adaptation to the prevailing acoustic recording conditions.

The microphone capsule is a pressure gradient receiver with two gold-plated plastic diaphragms. The capsule and microphone amplifier form a single unit and, due to their robust mechanical construction, ensure high operational reliability.

The microphone is connected using the C 57 microphone cable. The cable length between the microphone and the power supply unit can be up to 100 m. The UN 61 power supply unit is provided for power supply.

If the microphone is connected to a power amplifier with a 100 mV input, the UN 61 V power supply unit with built-in transistor amplifier must be used.

To mount the microphone, either a tripod in conjunction with the MH 43 microphone holder or the TS 58 table stand can be used.

The following measurements refer to a termination resistance of 1000 ohms.

Frequency range: 30 to 18,000 Hz

Directionality, switchable omnidirectional, cardioid, figure-eight

Field transfer factor: approx. 0.8 mV/µbar

Equivalent volume: approx. 24 dB

Total harmonic distortion at 200 µbar, 1000 Hz: approx. 1%

Gain at 80 pF equivalent capacitance: -0.5/+1 dB

Interference: < 1.5 µV

Output balanced: < 200 µV

Operating voltage: 120V

Anode current: approx. 0.9 mA

Heating voltage: 5.8V; Heating current. approx. 140 mA

Tube (low noise and sound). EC92

Weight: approx. 0.43 kg

Dimensions 420 x 190 mm

A post about the UM57 at the Coutant website.

A post about the UM57 at Vintage Microphone World.

UM57 transformer discussion at TAB-Funkenwork (My own experience with the UM57s is that the transformers are good enough when working properly).