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Music Valve Electronics U-47 Nuvistor Tube Adapter $195

If you would like to use your tube Neumann U-47 or U-48, but find that the tube has gotten noisy or has quit working, we at Music Valve Electronics Inc. have a soulution for you. We have recreated the adapter that Neumann designed to replace the VF-14 tube used in the microphone that allows another tube to be used. This is a plug-in adapter that installs in and out of the microphone in minutes. No modifications to the mic are required, so the value of your microphone is not affected.

We are not suggesting you remove a quiet, working Telefunken tube from your microphone to install that adapter, but if you can't obtain an original VF-14 tube for your mic, our adapter will keep your mic alive while you search out an original tube, and save up for the purchase price of up to $1500.

At only $195 for our adapter, we feel we are providing a viable alternative. Customers have called to thank us, saying that their microphone sounds so much better with a fresh, quiet nuvistor tube. If you should need to ever replace the Nuvistor, we can supply a tested, graded tube for $50.

Make no mistake, the 13CW4 Nuvistor used in the adapter is a tube. Designed toward the end of the tube era and incorporating the advances made throughout decades of tube design, the 13CW4 Nuvistor is a High-mu Triode tube. But let's read from the information sheet Neumann sent out in the 1960's:

Conversion of Neumann U-47 and U-48 Microphones to Nuvistor Tubes

(Nuvistor 13CW4 instead of tube VF-14M)

In view of the fact that Telefunken quite some time ago discontinued manufacture of the VF-14M tube used in the U-47 and U-48 microphones, NEUMANN has devised a means of converting these microphones from the VF-14M tube to another tube. Due to the fact that no completely equivalent tube is available on today's market, the adapter plug AR-47 must be inserted in place of the VF-14M tube, and the 13CW4 Nuvistor plugged into the adapter.

There are no changes required in the microphone itself. The NG power supply, however, must have a small change of wiring, due to the greater heater current required by the Nuvistor.

	a)  Replace the resistor R-2 (1 kOhm power resistor coming from + 
           terminal of rectifier) by a solid wire connection between the 
           first two electrolytic capacitors.

	b)  Install this same R-2 in parallel with r-3 (an identical resistor 
           next in the RC filter chain), thereby making its total resistance 
           value 500 Ohms.

After conversion, the U-47/U-48 microphone will have an output level 2-3 dB lower than previously. Due to the very high output level of these microphones, this is of no disadvantage.

Music Valve Electronics U-47 Nuvistor Tube Adapter $195




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