48V phantom powered valve capacitor microphone with 5 switchable polar-patterns

  • Legendary Georg Neumann M7 capsule with PVC diaphragms
  • 48V phantom powered

October 2022 – unfortunately, due to the non-availability of some essential components, Microtech Gefell can no longer manufacture the UM 900 as it is.  There may be a few demonstration microphones available that can be refurbished to new condition; please contact us if you are interested.

“The UM 900 is individually styled and innovative.
Its five switchable polar patterns, high pass filter
and attenuator make it a versatile microphone,
while its superb, warm but detailed sound quality
puts it amongst the best in its class.”
Hugh Robjohns, Sound On Sound, January 1999
You can see the complete review HERE

A modern classic in design. A modern classic in sound. The UM 900 is a low-noise large diaphragm valve (vacuum tube) microphone featuring the renowned Georg Neumann M7 capsule with sputtered gold PVC membrane.  Uniquely, it draws its power direct from a 48V phantom power supply source such as a console input.  The UM 900 has five polar-patterns selected by a switch on the body. The warmth, detail and smoothness owe much to the modern low noise valve circuitry, but the combination of the acoustically optimised shape of the body, combined with the classic handmade M7 capsule results in a studio microphone that satisfies the demands of modern recording whilst displaying all the best characteristics of a vintage valve mic.

The UM 900 is the first switchable pattern, valve condenser microphone which can be connected to the industry standard 48 Volt phantom powering using a normal 3-pin XLR microphone cable.  This is made possible by an advanced circuit design for the amplifier and internal power supply. The capsule uses a traditional, proven design with two large, gold plated PVC membranes.

Three switches are located around the body of the UM 900. The switch in the front selects the polar pattern: omni, wide cardioid, cardioid, hyper-cardioid and figure-8. Located 120 degrees to each side are switches for gain adjustment and low frequency roll-off.

The unusual shape of the microphone’s body is especially designed to minimise undesirable reflections of sound toward the pickup element.

Acoustic influences which could result from the housing resonance and/or mechanical vibration are reduced by the robust construction and by a special fixture within the microphone’s housing which dampens vibration.

The high sensitivity and low noise of the UM 900 make it especially suitable for vocal and speech pickup in professional sound recording studios, scoring stages and broadcast studios. The 5 polar patterns allow the microphone to be tailored to a wide variety of applications. For example, the microphone can be used as an overall pickup for a large orchestra or it can be used as a solo or spot mike for individual instruments. It may also serve as an announcer microphone where its proximity effect may be desirable.

The direction of maximum sensitivity is radial to the microphone body, i.e. side addressed. The front of the microphone is indicated by the model number and the pattern selector switch.

The capsule is mounted in a large, acoustically open headgrill which prevents mechanical vibration interference. This gives the microphone a clean, colourless sound characteristic.

The internal valve (vacuum tube) amplifier of the UM 900 can be powered by any external 48 volt phantom supply that can provide at least 4mA of current.

The amplifier uses a specially selected valve (vacuum tube).
An internal DC/DC converter provides all the necessary voltages.
The low impedance output is implemented with an operational
amplifier and balanced output transformer.

The UM 900 can be connected with a cable of up to 150 m length without any effect on sound quality.

THIS links to a Vimeo video, recorded in February 2015, showing the UM 900 as a vocal mic. for a female singer.

A Brief History of Microtech Gefell

UM 900 Data Sheet

Sound On Sound review

Optional accessories:
Aluminium flight case
Windscreen – W 81 (W 82 for EA 92/MH 80)
Pop screen – PO 70
Microphone holder – MH 80
Elastic suspension – EA 92
Separate power supply – N 200
Connection cable – C 70

Recommended – Håkan P110 Pop Killer – see HERE