Anyone who ones a vintage U-47 or U-48 microphone knows that the supply of original TELEFUNKEN GmbH VF-14M tubes is exceptionally limited and frightfully expensive [if you can find a good one]. Since Neumann GmbH ran out of their supply of original tubes in the early 1960's many attempts for substitute tubes have been offered with varying degrees of success. TELEFUNKEN Elektroakustik has found a suitable substitute which captures all of the "magic", "vibe" and "mojo" of the original tube.
Manufactured to be a direct "plug and play" retrofit for an original VF-14M tube socket [no modifications required], the VF-14k is employed in our U-47 and U-48 microphones. While all tubes differ in response [especially when they've been in use for the last 50-60 years], please note the frequency response chart below. This chart illustrates the minor differences between an original VF-14M and our newly created VF-14k. The test was performed in the SAME microphone [a historic TELEFUNKEN U-47 Serial #3957]. The difference is far less than the variation one would normally find between two historic U-47's placed side by side.
Q: What is a VF14K?
After considerable research, TELEFUNKEN Elektroakustik has located a glass tube, of obscure origin, originally manufactured for use in transoceanic telephone transmission. This not a Nuvistor tube, nor an EF86, both of which have been previously used as substitutes for original VF14's. By carefully modifying, by hand, the actual physical shape of the tube, we are able to place it inside the same metal enclosure, and with identical pin orientation, as the original VF14. The resulting sonic characteristics are extremely close to the original VF14.
The Telefunken VF14K is available with a 5 year warranty.