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Mods for the UM 57

  • HamptoneHamptone
    Scott Hampton repairs vintage tube mics, especially those needing new power supplies. His mic repairs involve replacing and updating selected components, fine-tuning the circuitry, and restoration of the mic's original sonic character. He can also furnish a Hamptone second-generation Tube Mic Power Supply.
  • The Mic ShopThe Mic Shop
    Bill Bradley restores vintage mics in Nashville, TN.

OmnidirectionalCardioidBidirectionalNeumann UM 57

Multi-Pattern Tube Condenser Microphone

The Neumann/Gefell UM 57 was a large-diaphragm tube condenser microphone manufactured by the Neumann company of Gefell, Germany, currently known as Microtech-Gefell.

The mic used the Gefell company’s famous M7 capsule. This was a dual-diaphragm, center-terminated capsule with a PVC (plastic) diaphragm. It supported three polar patterns via a switch on the power supply: Cardioid, Omni, Figure of 8.

Neumann/Gefell UM57 SchematicThe amplifier circuit is nearly identical to the Neumann/Gefell CMV 563, another tube mic manufactured at the Gefell factory. Both used the EC92 triode.

The UM57’s legacy was celebrated during Microtech Gefell’s 75th anniversary in 2003, with the introduction of the limited-edition UM 75, which was presented as a recreation of the UM57. However, numerous differences existed between these two microphones:

  • The UM 75 used an EF86 pentode.
  • The EM 75 used an updated circuit, similar to the UM 92.1 S (itself a modern reinterpretation of the UM 57).
  • The UM 75 used a transformer from AMI/Tab-Funkenwerk.

The UM57’s transformer was made by Gefell; the model number is T551.

Oliver Archut

9 out of 10 historic Gefell T551 [transformers] used in [the] CMV5/562/563 and UM57 [have] deteriorated, due to PVC wire coating, or wrong core material…

Oliver Archut mod to UM57 circuitDue to age, and a shortage of high-quality audio components in East Germany when these microphones were made, many UM57 microphones underperform their potential. Oliver Archut of AMI/Tab-Funkenwerk suggests numerous modifications to “move the [microphones] closer to the full potential of [the] M7” capsule:

  • Replace the Gefell T551 transformer
  • replace the original RFT Neuhaus EC92 tube with a Telefunken or Mullard EC92
  • Rebuild the power supply

UM57, photo credit: Markus SauschlagerThese and other circuitry changes are described in more detail in a forum post to PSW; see the sidebar link.

A 110V version of the UM 57 was created for the North American market; this model was called the UM 67.

Photo credits:
UM57: Bill Bradley / The Mic Shop
UM57 with power supply: Markus Sauschlager

The Neumann UM 57 is also known as: UM57.

The mic was released in 1957.


Pickup Patterns Pads & Filters
Omnidirectional (8 mV/Pa; 30 - 18,000 Hz)
Cardioid (8 mV/Pa; 30 - 18,000 Hz)
Bidirectional (8 mV/Pa; 30 - 18,000 Hz)
Capsule Dimensions Impedance SPL/Noise
Diameter n/a
200 Ohms (Low)
Weight Length Max Diameter Interface(s)
n/a 190mm (7.48'') 42mm (1.65'')
  • 3-pin XLR male (1)
Power Specifications
  • Includes tube power supply

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