Hi!
I have a gorgeous Neumann U48(like a 47, but different patterns cardiod and fig 8- Cardiod sounds different, since back plate is held at 0v instead of not connected or something-or-other. My original acetate diaphragm failed, as they do after 40 years. To my surprise, it sounded SO much better after capsule was replaced. Then Tube failed, Replaced with original Telefunken EF14 with modded Power supply by Ashley Stiles at Saturn Sound. Whilst I have to accept that the sound is not the same as with VF14, I have less problems with sibilent singers than before. The only true electronic replacement for a VF14 is a UF14, which was the stock item in the Siemens version of the U47/8. the heater voltage is lower, but I cant remember the value, perhaps it is 25V? If you check Telefunken Data, EF14 is NOT the same! I found some EF14's in Paris, but they were Wermacht originals left behind after the occupation, and none of them passed any test, especially microphony, since most of them were perfectly good microphones in their own right . . . . . I found one UF14 on evil bay for $14 in Slovakia! However when it arrived, the new cleaner( who was from Chech Republic) threw it out before I had achance to install it . . . no wonder they seperated . . . . . BAH! . . . . anyway, EF14 is more than adequate in my book, and I use mine every day, and that is the only test in my book. I LOVE MY U48, VF14 or EF14, Her Ni Ner Ni Ner!
Please contact if I can help at all.
Andy P