SATURN SOUND  Recording Services                        




Modifications - Neumann U47 and U48 (Electronics)


"Nuvistor" type, back to "Original" VF14 working

You cannot better the sound quality of a U47 / U48, when it is working around the "Famous" Telefunken VF14 valve. Over the years, service engineers (including myself) have tried using various other valve types in the U47 / U48, such as the EF14 and UF14, with varying degrees of success.

Neumann designed a modification that allowed the use of the 13CW4 "Nuvistor" type valve in the U47 / U48. Alas, the sound qualities obtained from a U47 / U48, fitted with a 13CW4 "Nuvistor", are not to every bodies taste. Also, due to the high running temperature of the 13CW4 when used in the confined / unventilated space of a U47 / U48, the life expectancy of the "Nuvistor" is quite short..

  Telefunken VF14 and 13CW4 "Nuvistor" assembly

Through the use of the new "Missing Link" RV-14m, a replacement valve for the VF14, we can again appreciate the full virtues of the U47 / U48 microphone.

See "Customer Feedback".

If you have an "Standard" Neumann 13CW4 "Nuvistor" modified U47 / U48 kit i.e. including the original PSU and lead, then it is quite possible to Retro' Mod' the microphone etc, back to the original Neumann VF14 design.

Price, please contact

Note - The price quoted, does not allow for any additional work required to carry out the modification. i.e. Re work due to previous non-standard modifications to the circuitry etc.

  The "Missing Link" RV-14m

U47 / U48 with "Non-standard" valve

If your U47 / U48 uses any other "Non-standard" type of valve, then it might still be possible to Retro mod' the microphone and PSU back to the Original Neumann VF14 design.

Price, please contact

Note - The price quoted, covers the cost of  "Rebuilding" the electronics of the microphone and PSU. Together with "Rewiring" the microphone to PSU cable. Also including the following new parts i.e. valve holder, capacitors and resistors.

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.

  U48 during a "Modification'" - Before and After

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