VF14ME???

[MicDaddy]

After some good ol' fashion haggling the seller has offered to let it go at quite a discount with the following:

"Since this is item is only being sold to a very specialized group of U47 and U47 microphones, I wonder if there is a chance that we might discuss this further. My number is ######## Brian"

I won't call tonight but will try to find time tomorrow.

 

[Moby]

@MicDaddy. Well done mate.

 

[Pip]

If this is really going to happen at a reasonable rate I'm in for one or two.

 

[chefducuisine]

I like the DIY route better. Isn't that what this forum is about???

Apart from the known alternative from Ethan Winer I found a couple of good reads on the net:
1.) Fetron: http://hrsasa.asn.au/docs/Fetron.pdf (check Page 28).
2.) Unfortunately German only http://www.radiomuseum.org/forum/roehrenersatz_durch_transistoren.html
3.) In the past there was a nice article on the Pimmlabs Website. Unfortunately it is gone now but I made a PDF (attached).
I ordered some parts two years ago but those are still sitting on the shelf...

 

[gyraf]

..the Pimmlabs approach does not compute: IRF820 power Mosfet has an input gate capacitance of typ. 360pF - waaay over useable range for condenser head amp duty..

Jakob E.

 

[chefducuisine]

Jakob,

of course you are right. 
I did not check this myself. :-[
My intention was more to orientate on the schematic from Pimm Labs rather than the data of a specific part that has been used.
Sorry for not being clear in the first place...

 

[Moby]

..the Pimmlabs approach does not compute: IRF820 power Mosfet has an input gate capacitance of typ. 360pF - waaay over useable range for condenser head amp duty..

Jakob E.

Right, seccond issue with this kind of approach would be the input impedance to accept capacitive source.

 

[gyraf]

This may be interesting - as the right way to FET a U47

Fetrons designed to replace vacuum tubes "408A" (which is probably the best current replacement for the VF14 tube)

https://www.ebay.ph/itm/Teledynamics-Semiconductor-Fetron-TR-1001-Vacuum-Tube-Replacement-4-NOS/362151523895

Jakob E.

 

[Gus]

I have built a few solid state tube voltage circuits for microphones.
I have a few more circuit prototypes to build and test.
The issue is liability selling a PCB or complete microphone that plugs into a a tube voltage power supply.

 

[pucho812]

price drop to 295


https://reverb.com/item/1410282-grove-hill-audio-vf14me-electronic-tube-alternative-last-one

 

[CJ]

i bet that thing is encased in JB Weld,

 

[Timjag]

If anyone is interested in the Fetron datasheet/bumph

http://hrsasa.asn.au/docs/Fetron.pdf

 

[Recording Engineer]

I’ve the Phaedrus Audio version, but have hardly done any listening at all yet. However, so far, next to a brand new Telefunken VF14k I have, I have no complaints. I really can’t say at all yet, but so far I’m getting the feeling that the differences will be so minut that I’d much rather the Phaedrus since it’s so much cheaper.

 

[Gus]

I think a blend of the good parts of a solid state microphone design and what makes a tube microphone sound like a tube microphone combined in a solid state microphone can be good thing and can be a useful addition to condenser microphone design.

FWIW I have built a few prototype circuits one can drop in for the tube in a M49c like circuit, another is a circuit to drive a larger 6.5:1 transformer, that one is built in a 47 like body powered by 120VDC supply.

IMO
A Fetron is not what you want.

 

[Whoops]

It is already a philosophical question. Depends on what he eats and if he is healthy. More or less poop stinks. I have a sensitive nose. I admit

LOLOLOL

Love this Post

 

[mhelin]

How close to VF14 you could get by using a hybrid design like on Manley Reference Silver (FET + 5670 )?

 

[emrr]

You guys missed this version, which looks to have been out there a long time:

http://www.saturn-sound.com/products/replacement%20valve.htm

http://www.saturn-sound.com/products/rv-14m_design_and_construction.htm

http://www.neumann.com/forums/view.php?site=neumann&bn=neumann_mictec&key=1314438468

https://groupdiy.com/index.php?topic=11003.0

 

[Recording Engineer]

How close to VF14 you could get by using a hybrid design like on Manley Reference Silver (FET + 5670 )?

I would have not thought that that’s what they’re trying to do there... Since they didn’t just go straight-up more Sony C-37a -like, I would have thought that they were somewhat doing they’re own thing while still linking with to the C-37a -like capsule... About time Manley did something like that with their Josephson connection.

 

[rmburrow]

This may be interesting - as the right way to FET a U47

Fetrons designed to replace vacuum tubes "408A" (which is probably the best current replacement for the VF14 tube)

https://www.ebay.ph/itm/Teledynamics-Semiconductor-Fetron-TR-1001-Vacuum-Tube-Replacement-4-NOS/362151523895

Jakob E.

Tried two 408A tubes, heaters in series?  Tried a 407A, heaters in series and paralleled sections to get plate impedance down?  The old 13CW4 nuvistor modification by Neumann effectively was an "emergency" fix to keep the VF14 equipped mics running.  Had a long phone conversation with the late Oliver Archut about "acceptable" VF14 replacements...

Change some cable wiring and modify the PSU (or use 3rd party PSU) for 6 v heater,  the EF14, EF13, or EF800 should work... be careful and work carefully on a valuable mic; construct any tube mods on a plug in adaptor, do not remove the original tube socket or do anything else that is irreversible.