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Modifications - Neumann Gefell CMV563 and UM57 (Electronics)


Neumann Gefell CMV563 and UM57, conversion to Neumann U47 electronics

The CMV563 and UM57 are fantastic microphones and can still be found at sensible prices. 

The CMV563 will normally be found with, at least, the M7 or M7s "Cardioid" capsule. Ideally it should have the M55k "Omni", M8 or M8s "Fig' 8" and M9 or M9s "Small Diaphragm Omni" capsules also. Whereas the UM57 uses the M7 capsule as standard. The M7 capsule being that used by the Famous Neumann U47 microphone.

Both the CMV563 and UM57 microphones lend themselves to a very effective modification i.e. To convert the electronics to that used in the legendary U47. The only component not being changed, being the out-put matching transformer. This being due to the lack of space within the microphone body.

  UM57 (Upper) and  CMV563 with M7s capsule (Lower)

The modification uses the "Missing Link" ML-1955 Low Noise Pentode, as used in the RV-14m valve assembly. The later being a direct replacement for the "Telefunken" VF14m.

After modification, the "Self Noise" is considerably less than that of a "Standard" CMV563 or UM57.

Both the "Modified" CMV563, with the M7 capsule fitted and the UM57, will "Basically" sound like a U47. However, due to the fact that the CMV563 / UM57 still uses the original out-put matching transformer, the sound quality will be "Somewhat" different to that of a U47 i.e. Very close, but not exactly the same.

Alas, there is insufficient space to fit a genuine U47 type out-put matching transformer inside the CMV563 or UM57 microphone assembly. However, the final results are very impressive. See Customer Feedback

  Inside a CMV563, before and after modification

The associated power supply, N61 or UN61, will also require a complete rebuild.

Inside the Neumann U47 and U48, a large wire-wound resistor is used to drop the HT voltage, to that suitable for the valve heater. This being one of the reasons why a U47 or U48 runs so warm. Again, there is insufficient space in either the CMV563 or UM57 to allow the fitting of such a resistor, therefore this component is fitted within the associated power supply unit.

Price, please contact

Note - The price quoted covers the cost of  "Modifying" the electronics of the microphone and PSU.

If the Capsule / Out-put Matching transformer / Tag Board / Lead (Including some types of Connectors) are Non-Standard or Faulty, then additional charges will be incurred.

  "Modified" N61 power supply, with additional ventilation
Customer Feedback

"..... I really donít know what to say. ..... The CMV563 that you converted is breathtaking ....."

Dermot Rooney

"..... you did the modification on my Neumann Geffell UM57 ..... how thrilled I am with the results. We have only recorded vocals with it as yet, but very wonderful it sounds on this simple but vitally important task. Sweet and silky high frequencies, solid warmth and really delightful subtle compression from the valve. I remember the mic' sounding good before but now it sounds as if it has lost nothing of its former magic but gained an expensive and classy sounding quality."

Martin Turner, Wishbone Ash



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