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[Martin Kantola]

Fletcher wrote on Fri, 03 July 2009 13:55

I understand you have an agenda, but slagging our product is a bit out of bounds until you've used it in the field.

As I explained in my later post, I got the wrong idea of what TFK USA were doing reading about it, that's all. First quite excited, and then a little disappointed, I'm sure you understand.

As you say, I have no idea or opinion on how the new (substi)tube performs. Make me happy and send me one for testing

No need for cursing.

Martin

[kats]

You did not get the wrong idea, you shouldn't have to apologize. They advertised it exactly the way you perceived it, only to remove certain claims once internal pictures of the VF14K were made public by another source.

I think this is the only mic in the world or perhaps in history where you are not told what the exact valve used in the amplifier is.  

[seedyunderbelly.com]

The VF14K represents the first newly machined metal envelope tube presented by Telefunken USA. Manufactured in the United States, the VF14K tube functions exactly like the original VF14 and features the same sonic and electronic characteristics found in the classic Telefunken tubes.{/quote]

Are the tubes available?  I would think if people are asking 6k for a VF14-  If they are as good  perhaps they could make a good business out of it no?

[Doc B.]

Quote:

Short of that confirmation, let me quickly add: My asking price for a VF14 (which is by the way well within 'M' specs, and you have to believe me, because somebody, whose name I forgot, said so!) is currently $16,000.000 (that would be sixteen million dollars.)

Sorry guys, you missed out. I negotiated a deal with Klaus at lunch yesterday and bought it purely with the intention to flip it.My asking price is $32 Million. Klaus assured me that this one is a very rare factory variant, and easily the most collectible VF14 of all.

[Lukas Heyer]

(...)For some, it may simply be hard to believe, that (from a VF14) an entirely different tube:  "a suitable substitute which captures all of the “magic”, “vibe” and “mojo” of the original tube." (source)  "offers equal sonic performance to the VF14" (source). (Quotes from Telefunken Elektroakustik Web site, as of 05. 07. 2009.)

When, sometimes, it is very easy to hear not-so-slight differences between same tube types of different manufacture, especially in a microphone. Personally, I do not have any experience w/VF14-equipped vs. EF14 U47s, but e.g. Oliver stated (on this site) that even the EF14 retrofit does not sound exactly the same, and those are very similar tubes, when it comes to their internal construction. They are not. Please read previous posts and threads and stickies on the subject. K.H.

I have nothing against Telefunken Elektroakustik, they seem to be really passionate about what they do, but I would certainly choose my words more carefuly when advertising the 'VF14k'.

[Lukas Heyer]

KH wrote:

They are not. Please read previous posts and threads and stickies on the subject. K.H.

Klaus, I did read the posts. Oliver wrote that "The EF14 is nearly identical from a technical point of view", so I believe we -can- say the tubes really are similar, when it comes to their internal construction (Oliver: "[...] both tubes share the same part aside the filament"), i.e. cathode and anode sizes and distances are the same, grid assembly etc. According to Oliver, the VF14 features:

-different filament, of course
-different base material and cathode sleeve insulation
-mica wafers with high impedance coating
-high impedance tube base
-"plus a few other minor details"

On the photos of the innards Oliver posted a while ago, VF14 and EF14 systems looked to be very similar. These modifications mentioned above and special assembly precautions would indicate that VF14 was a special quality tube (compared to EF14) - perhaps made with the intention to get better noise figures, long-term stability and reduced interelectrode leakage - with similar construction, but, as some say, somewhat different sound.

[J.J. Blair]

The photos were VF14 and a UF14, and they were extremely different.

I would love to see the inside of an EF14.  I should ask Dave Pearlman if he has any dead ones available for dissection, unless an of you have pictures.

[Klaus Heyne]

Quote:

-different filament, of course -different base material and cathode sleeve insulation -mica wafers with high impedance coating -high impedance tube base -"plus a few other minor details"

Lucas, it may come down to what you and I define as 'very similar' in the design, material and manufacture of these octagonal tubes.

One thing you left out in your list is probably the single most relevant structural variation between the VF14 and the rest of the VF family- the proprietary cathode material and its doping that was used only in the VF14.

Also, as has been discussed elsewhere, a UF14 heater voltage one-third (or in the case of the EF14, one-sixth) the heater voltage of that found in the VF14 may significantly influence the dynamic behavior of the electron emission process in a U47.

Taken together, the VF14's sonic behavior cannot and does not equate to that of the rest of the VF family when modified to work inside a U47.

[Martin Kantola]

Klaus, have you ever experimented with different biasing methods with the VF14 and how they affect the sound?

It seems difficult to judge the sound of the tube itself since there always has to be a circuit built around it, and with the EF and VF these can never be 100% identical (if the original U47 style biasing is used).

Martin

[Klaus Heyne]

Yes, I have.
The starkest sonic difference through biasing variations can be obtained by using cathode biasing with bypass cap:

the noise floor of the tube will go down by about 2-3 dB, but the mic will sound like hell, and not a thing like a U47: glassy, overly transparent to  the point of washed out, anemic in mids and lower mids- altogether quite unattractive.

[Lukas Heyer]

J.J. Blair wrote on Tue, 07 July 2009 18:10

The photos were VF14 and a UF14, and they were extremely different.

Perhaps we both mean different photos, I am talking about a photo Oliver posted, showing innards of a UF14 (which certainly looked to have a different construction), EF14 and two versions of VF14. Unfortunatelly, w/this server's archiving system, it is hard, if ever possible to find it, but I still have it and if Oliver has nothing against it, I can re-post it here. Oliver?

[quote title=Klaus Heyne wrote on Tue, 07 July 2009 19:36]

Quote:

One thing you left out in your list is probably the single most relevant structural variation between the VF14 and the rest of the VF family- the proprietary cathode material and its doping that was used only in the VF14.

I believe I wrote (or better: transcribed Oliver's finding) that the cathode base material is different? I read in several tube manuals, that with special quality tubes, it was often a practice to use passive nickel alloys (P50 etc.) for cathodes and I suspect it may have been the case w/VF14 as well?

Anyway, my point was not to prove that EF14 and VF14 sound the same, quite on the contrary: that despite their similar construction and electrical characteristics, some still think they sound rather different, even w/circuit adjustments. And if this is the case, could an entirely different tube (at least that was what we have seen on the photos of that dissected VF14k) 'offer equal sonic performance to the VF14'?

I was questioning the style of the VF14k advertisement, nothing more, nothing less.

[Klaus Heyne]

Lukas, thanks for the clarification.
I am ready to test anyone's VF14 replacement, with neither a more nor less critical ear than I would apply to any of my testing (and I have heard some awful VF14s!)

[KaiS]

Klaus Heyne wrote on Tue, 07 July 2009 15:37

The starkest sonic difference through biasing variations can be obtained by using cathode biasing with bypass cap...

So the other way round - what would be the best circuit to approximate the VF14 sound using an EF14?

Kind regards
Kai

[MDM,]

J.J. Blair wrote on Tue, 07 July 2009 12:10

The photos were VF14 and a UF14, and they were extremely different. I would love to see the inside of an EF14.  I should ask Dave Pearlman if he has any dead ones available for dissection, unless an of you have pictures.

JJ, Oliver had posted a photo of the EF14 inside, along with the others you mentioned..

it was on PSW year(s) ago?

apparently the difference between the inside of ef14 and Vf14 is the filament, which in the VF14 is wired as a long loop because of the high filament voltage.

if you look at a lightbulb when it's under-powered you will see that only the central part becomes hot, and in the EF14, which has a shorter filament (possibly filaments wired in parallel) the same thing happens.

so in an EF14 if you under-power the heater, you only get the central part of the cathode hot, while the extremities remain cool... in a VF14, since the heater filament is looped-up, the central part actually heats all of the cathode more or less.

then Oliver mentioned that the connector-base of the tube on the VF14 is superior and has less resistance and capacitance if I remember correctly.

[Oliver Archut]

if you use the forced bias circuit that is set to the EF14, removing the 1750 Ohm resistor and exchanging it with a 35 Ohm resistor (to keep the same heat dissipation but that need to be  handmade from scratch) and run it with approx. 12V supply and 1.1V on the cathode, 5.05V filament you will get an technical identical scenario, that requires a new PSU and extensive modification.

If you now can hunt down an EF14 that were made in the time frame 1946 to 1954 (to have the most similarities in construction to the VF14) that exhibits the same microphonics and noise specs than the VF14 (about 1 or two of 10 standard EF14) you end up with a mic that is close but it is still not identical.

A fews year ago the cost of the proper done modification was just a bit less than a VF14.
With the price spike of everything related to the U47 the EF14 is sold now around $200, so with getting 10 to have one or two usable ones, again you will end up just a few buck below the current VF14 price.

Best regards,



Best regards,