Microtech Gefell UM900

Large diameter dual diaphragm capsule, switchable


The UM 900 is the first switchable pattern, tube condenser microphone that can be connected to industry standard 48 Volt phantom powering using a regular 3-pin XLR-microphone cable. This is made possible by an advanced circuit design for the amplifier and internal power supply.

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 adjust and low frequency roll-off.

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

Acoustic influences that 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 that dampens vibration.

The pickup capsule uses a traditional, proven design with two large, gold plated plastic diaphragms.

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 pickup patterns allow the microphone to be used for a wide variety of applications. E.g. the microphone can be used as an overall pick up for a large orchestra or as a solo or spot mike for individual instruments. It can also be used as an announcer’s microphone where its proximity effect is 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 pick-up capsule is mounted in a large, acoustically open head grill that prevents mechanical vibration interference.

This gives the microphone a clean, colorless sound characteristic.

The internal vacuum tube amplifier of the UM 900 can be powered by any external 48 Volt phantom supply that can provide at least 4 mA of current. The amplifier uses a specially selected vacuum tube. An internal transverter provides all the necessary voltages. The low impedance output is implemented with an operational amplifier and balanced output transformer

The microphone features 5 pickup patterns: omni, wide cardioid, cardioid, hyper cardioid , figure 8.
3 positions can be selected.

NOTE: When the “+4 position is selected the pattern switch on the front of the microphone is disabled. Only the cardioid pattern works at the higher sensitivity of +4 dB. 2 positions can be selected: The sensitivity at 70 Hz is reduced by 10 dB in the position

• Dark bronze finish
• Satin nickel finish
• Bass roll-off switch
• Level increase gain 4 dB
• Level reduction pad 10 dB
• Balanced output transformer