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[Sueshoes]

Hi all, need advise...

U47 vintage needs the dreaded & elusive VF14 replaced....  Ahhhhh!

This is my baby had her for years and I am told by Neumann in CT that the tube needs replacement.  What do I do?  I can't imagine not having "my mic" ....  This mic cant live on my shelf....

Suggestions...  Advise.... 

Oh how I dreaded this day.... 

Suzie

[klaus]

From experience I am skeptical about VF14 diagnoses. Tube socket contact behavior often masks as tube failure.

I advised the owner in a PM to get a second opinion about the tube's condition before despairing.

[J.J. Blair]

Told by Neumann in CT or Telefunken in CT?

[Piedpiper]

If indeed it does need a replacement, Andreas Grosser makes two drop in replacement options available including the VF14 ER, a glass tube, and the VF14 EF, an appropriately socketed FET based replacement. Regardless of how close they sound to a real VF14 or not, they should work as a stop gap at the very least.

[klaus]

I assume, the above recommendation is based on your personal experience in both cases?

Please clarify.

Thanks,
KH

[Piedpiper]

I appreciate your calling for this distinction. As you know, it is common knowledge that they exist and that they function as advertised, which is to say they work in an unaltered U47 circuit and sound similar but slightly different to a VF14. I am not here to claim how similar or how different.

Although I don't personally own an original U47 nor one of Andreas' tubes, I have heard recordings of a comparison between Andreas' tubes and a VF14. I noticed subtle but noticeable differences, thus my point that they are not identical, but "work and sound very well as a stop gap at the very least."

Ironically, I actually preferred the glass tube to the original in some ways. I believe I made my post informative and helpful without claiming anything inappropriate. I suppose it is possible that the availability is dated information, since I have not personally confirmed this recently. Feel free to point out my error.

[klaus]

I find it speculative on your part to recommend an audio device which you have not personally heard.

How can I possibly derive any meaningful information about the value of a substitute tube from my position as a consumer of a sound sample whose test setup I did not personally witness?

This is not a critique of your listening abilities of sound samples, but a critique of your methodology of truth finding, even if it just is a subjective truth.

I can make an SM 57 sound good next to a U47, as long as I don't have to reveal how I recorded both mics.
In that light, a sound sample comparison is not any different from a laundry detergent ad on TV where one shirt looks as white as the next, after massive manipulation of the test set up.

[Piedpiper]

understood... my emphasis was on the fact that they are a functioning drop in replacement, not on how well they replicate the original's sound. I tried to make that clear. I will try to edit my original post to make it even clearer.

[klaus]

Good point. Thank you.

[NVS]

I replaced my original VF14M with Andreas Grosser’s VF14EF (a transistor/solid-state device-K.H.) and I love it. There is a slight difference in that there is a little less of the K2 and K3 harmonic distortion in the VF14EF, so the original sounds “a little bit more exiting” (for the lack of better words) but it still has “that sound” to it. And it is of course way cheaper, probably faster and maybe even safer than getting an original. I also like the fact that I no longer have that “VF14 failure scare” in the back of my head. But, that’s me.

I’ll admit to the fact that an original VF14 is the best, and I might try to get one someday, but for now I’m not gonna be bothered, because of how good the VF14EF sounds. Yes, my U47 is no longer all original, and its value has dropped, but I’m still enjoying the hell out of using it.

If it still is an issue, then my advice is to contact Mr. Grosser. I know he only sells the solid state replacement after personally checking the mic, and its tube, but he is, in my opinion the nicest and most helpful guy in the history of mankind. He actually let me test the replacement (in my studio here in Norway) before I paid for it, and (I can) just return it if I didn’t like it.

By the way, I tried one of the other “glass-tube-inside-plug-and-play” (not VF14ER which I have not heard) options available and it wasn’t even standing outside looking into the ball park! I have also heard several 47 clones with EF14, EF800 and none of them sounded like a 47 to me.

[klaus]

Can you tell me what a "VF14 EF" is?  You mention "tube" in your post, so I assume, it's not a solid state device? Any type/number identifier on it?

[NVS]

The VF14EF is a solid state device, using FET transistors. It’s not a tube. We just call it a tube. Sorry about that, I just assumed you knew.

Not sure what you mean: “Any type/number identifier on it?” There is a serial number on it, but that’s about it (other than the “AG VF14EF” sticker).

[klaus]

Let's not call a solid state device a "tube". That is just too confusing. I have edited out your 'tube' references in your post and replaced it with "solid state device" Hope you don't mind.

[NVS]

Nope, I do not mind. 

[rmburrow]

Ms. Sueshoes...I fully understand your situation with the failing VF14 in your U-47.  A number of years ago, a friend of mine was in a similar situation with his U-47.  This friend of mine and I built a plug in adaptor using a Western Electric 407A dual triode with both sections paralleled to get the mic working again while he hunted for another VF14.  (Turned out the B plus was right on 105 volts from the NG supply, and a scope showed extremely low ripple.)  A AR47 kit was ruled out due to the mismatch between the nuvistor plate and the output transformer impedances.  The 407A worked well enough my friend abandoned searching for a VF14.

I am hoping that Klaus Heyne or Oliver Archut have specific comments concerning any tests they ran using the 407A in the U-47.  The 407A was designed for use in telephone repeater and h.f. circuits where low noise is essential, and has a 40 volt heater that works fine in the U-47 without making modifications within the mic itself.

Sooner or later, some acceptable substitute for the  VF14 needs to be found before that tube goes the way of the dodo bird or the passenger pigeon...

[klaus]

Yes, familiar with the WE 407. Tried it, years ago, upon the suggestion of Oliver, and it sounded (at least to me) thin and glassy. I also assume that the Telefunken/USA "VF14K" glass tube-within-a-steel-tube jacket they are selling is that tube. Someone correct me if I am wrong and you know for certain what that tube is.

I guess, the 407's appeal is primarily that it requires no major power supply changes from Neumann's original VF14 set-up, and, aside of tube socket changes, (when not using Telefunken/USA's tube) that must have been an appealing consideration for all who tried it. 

All things being equal, the EF14 or UF14 solution to the VF14 shortage remains the sonically more appealing work-around, despite its sonic shortcomings

A postscript: a Finnish fellow just emailed me that he has three new-in-box VF14s for sale. This on top of various collectors who sit on hundreds or more of these things...

[David Bock]

  (Turned out the B plus was right on 105 volts from the NG supply, and a scope showed extremely low ripple.) 

There should be NO ripple from an NG connected to a U47.

[J.J. Blair]

Klaus, have you listened to EF14 conversions, when paired with Oli's BV8 type, frequency balanced for the EF14?

[klaus]

I have not.