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[YZ]

Folks,

It's getting harder and harder to find original tubes for the classic microphones, and those parts are needed in order to keep their resale value; I know that there's no practical replacement for a VF14 in a U47 that would keep the mic's sonic signature, but what about the other classics?

I mean, is there a functional replacement for the AC701 of the M-series, a tube that would keep the mic sounding close to the original in a situation where the owner wants a working mic, not a prized antiquity?

And what about the tubes of the other classics?

As time passes and the original tubes disappear, I'd hate to see many otherwise fine microphones remain silent due to their exhausted tubes.

[Klaus Heyne]

I am hopefully not suppressing differing voices, when I chime in early on this subject.

It is my sincere belief that someone who owns a $10,000.- microphone should not even think twice to spend roughly 1/7th or 1/6th of its value on one of the core components (which, by the way, will outlast the owner, and then some!) to make the mic work as intended, and which will, unlike other tube options chosen, retain (or, more precisely, appreciate in) its value.

There are plenty of VF14 tubes out there to satisfy the needs as they arise (even without the recent fakery of a "find"  of supposedly 400 VF14, which I finally deleted, because the supposed owner did not own up to it.)

The same can be said of AC701. There are easily several thousands of these tubes around, and again, once one of these low-noise versions has been properly installed and its power supply adjusted, it should last for decades if treated right (see sticky on AC701.)

Finally, the EF86. Here, too, there are plenty of NOS available, if you can spare the right amount of change, but the competition with other hifi gear users is starting to become an issue with this tube.

In all of the above cases, only owners who could not really afford the original vintage mics which used these tubes would accept what is offerend on the market as lower-priced 'alternatives' (none of which enhance the mics, and all of which, in my opinion, remove some or most of the character of the original.)

[YZ]

Klaus Heyne wrote on Sun, 06 July 2008 03:10

what is offered on the market as lower-priced 'alternatives'(...), in my opinion, remove some or most of the character of the original.

Which is a pretty straight answer; thanks for being so clear.

[Jørn Bonne]

Klaus Heyne wrote on Sun, 06 July 2008 08:10

It is my sincere belief that someone who owns a $10,000.- microphone should not even think twice to spend roughly 1/7th or 1/6th of its value on one of the core components (which, by the way, will outlast the owner, and then some!) to make the mic work as intended, and which will, unlike other tube options chosen, retain (or, more precisely, appreciate in) its value. ... In all of the above cases, only owners who could not really afford the original vintage mics which used these tubes would accept what is offerend on the market as lower-priced 'alternatives' (none of which enhance the mics, and all of which, in my opinion, remove some or most of the character of the original.)

Veteran studio owner and vintage microphone dealer and enthusiast Dan Alexander wrote this in a recent thread on the internet:


"As for the matter of ef14 vs.uf14 vs. vf14 tubes, the simple fact is that the performance of these tubes, given the proper powering voltages , in the normal u47 circuit is identical. Several of the dozen or more U47s I sold to Shelley Yakus at A&M were uf14 retrofits, and they were some of his favorite microphones of all time . He was well aware that the mics had been modified when he purchased them …The fact is that all of these tubes were discontinued being made in 1939, so good luck obtaining a n.o.s. replacement VF14 with the Neumann “m” designation…"

and ....

"again , over the years, we have retrofit at least (30) u47s with uf14's, and they are , and I say this without equivocation, every bit as good, and identical sounding, as any with a vf14"



Has anyone else ever heard any of these re-tubed U47's and come to the same conclusion as Mr. Alexander?

[Klaus Heyne]

This subject has been beaten to death on this forum, it's also covered in the 'stickies' section, but you may not be aware of it.

I can give you three arguments for not converting a mic that was meant to be used with VF14 to substitute tubes. But I don't know whether you would find any of these arguments convincing.

1. The material composition and construction of crucial components of the VF14 differs from that of the EF14 and UF14. If similar material differences in other microphone tubes result in a clearly audible diference experienced my many (f. ex. comparing currently manufactured Russian to NOS Dutch or German EF86), it is reasonable to assume that these material differences will also be audible in VF14 substitutes made with different materials.

2. I installed a few UF14 and EF14 tubes in stock-original U47 mics over the years and, despite taking care not to overheat the tubes, and properly biasing them, in all instances the U47s with these tubes sounded clearly different to me. I did not appreciate that difference, and un-did the modification in all cases, recommending to the client to find a VF14.

3. There is at least a remote chance that a person who is recommending these kind of substitute tubes for U47s or their clones may have a financial interest in his recommendation. It is up to the potential buyer of such tube conversion to investigate that possibility and evaluate recommendations accordingly.

[Oliver Archut]

Dan Alexander, quoted from another forum:

Quote:

As for the matter of ef14 vs.uf14 vs. vf14 tubes, the simple fact is that the performance of these tubes, given the proper powering voltages , in the normal u47 circuit is identical. Several of the dozen or more U47s I sold to Shelley Yakus at A&M were uf14 retrofits, and they were some of his favorite microphones of all time . He was well aware that the mics had been modified when he purchased them …The fact is that all of these tubes were discontinued being made in 1939, so good luck obtaining a n.o.s. replacement VF14 with the Neumann “m” designation…

It is quite funny that always those people that sell EF14/UF14, etc. are pointing out how good they are compared to the real thing.
Also the last VF14 was made in 1954, the last EF14 in 1952, UF in 1950, so were is the 1939 coming from? The VF14 was first made in 1946/47 and there is none before that timeframe...

I know for sure that there are several hundreds VF14 out there, most people that have them, bought them as an investment and if you are willing to pay their prices, you will end up with a bag full of them.

Over the years I worked with several U47 owners trying to get the short cut to a working U47 without a VF14 and in the end nine out of ten people bit the bulled and bought a VF14 because all of the replacement tubes sucked compared to the original.

I guess the Telefunken tube data reveal the facts, so check it out.

By the way, why is it not so that if you buy a U47 with a VF14 at a vintage tube dealer  is the same than a U47 with an EF or UF? I guess that brings it to a point.

Best regards,

[MDM,]

Oliver, your post only shows the difference between EF and UF.. the VF is not there..it says to look under EF14.. so technically VF and EF are the same except for heater filament.

but there is a difference, which perhaps would dissapear to a point if VF14's in U47's weren't underheated.

the problem with EF14's is that if you underheat them not all of the cathode heats up properly.

if you've ever seen a lightbulb which is underheated you see that only the central part is red, with the extremities being cooler.

in a vf14 this doesn't matter much because the filament is long and coiled against itself, so the 'hot part' heats up pretty much all of the cathode..

in EF14's this is not really possible, so you need to heat it up a little more, which makes it sound more agressive and hard, in my experience..

but I personally preferred a new EF14 over an old worn-out VF14.. as I did a comparison between two original bodies (with good caps and VF14) and one with EF14..

however, if you can find a like-new VF14, the result will be better.

[Jørn Bonne]

Oliver Archut wrote on Tue, 08 July 2008 04:06

It is quite funny that always those people that sell EF14/UF14, etc. are pointing out how good they are compared to the real thing. Also the last VF14 was made in 1954, the last EF14 in 1952, UF in 1950, so were is the 1939 coming from? The VF14 was first made in 1946/47 and there is none before that timeframe...

Yes, not very reassuring...
People are being misled and I think it is important that correct information is made available to guard against the urban myths. Thanks Oliver.

Thanks also to Klaus and Max for the additional info. Keep it coming.

[Oliver Archut]

Hello MDM,

The data says that the EF/VF14 is technical identical, but my only point is the application info: only the VF14 says "microphone amplifier", and this is exactly what has been pointed out here on this forum for a long time.

You are right with the underheating issue of the VF14, aside the different wound filament, the VF14 has a double helix- type wound on an aluminum oxide rod, were the EF14 has a folded one, there are several small but important differences.

All other Telefunken-made tubes used in studio application have a double Helix filament too!
Aside the different heater, the cathode alloy is different to as well as the coating.
There is a bunch of info in the archive of this forum and in the stickies.

Best regards,