Measured VF14 characteristic

bezen4uk · Sep 17, 2013

Hi guys,
I had opportunity to make thorough mesuring test of the mint VF14 tube.
Tube is marked with "M", "Bld 00" and "432".
I choosed heater voltage same as in Neumann U47.
I used Fluke 8050A as multimeter and L1-3 tubetester as power supply.
Enjoy the graph.
Also, I made some measurements of amplification factor in original U47 mike, will post later.

moamps · Sep 18, 2013

Hi,
thanks for your effort and time.
Could you please measure the heater current for 35V, 40V and 45V?
Regards,
Milan

bezen4uk · Sep 19, 2013

Hi moamps,
Added heater current graph.

gyraf · Sep 19, 2013

Thanks

Melodeath00 · Sep 19, 2013

I wish I knew what any of this meant

HellfireStudios · Sep 19, 2013

Melodeath00 said:
I wish I knew what any of this meant

If I'm not mistaken, they are probably attempting to find a suitable replacement/alternative.

-James-

Melodeath00 · Sep 19, 2013

HellfireStudios said:
Melodeath00 said:

I wish I knew what any of this meant

Click to expand...

If I'm not mistaken, they are probably attempting to find a suitable replacement/alternative.

-James-

Yes, and I admire that. I just meant I personally don't know how to read the graphs. ;D

bezen4uk · Sep 19, 2013

Interelectrode capacitances:
Grid to plate: 2.6pF
Grid to cathode: 6.7pF
Plate to cathode: 12.5pF

Notes: G2 and G3 connected at plate. Shield and filament connected to cathode.
Measured directly at tube pins (without socket).
Measuring method is tested with different tubes with known capacitances and gives tolerance 0.2 pF.

Moby · Sep 21, 2013

Thanks. Nice share.

bezen4uk · Sep 21, 2013

Thank you guys for feedback.

There is EF80 characterstic.
Mu=45, while VF14 has mu=28.

bezen4uk · Sep 24, 2013

There is another tube - russian nuvistor 6S51N-V compared to VF14.
They look pretty similar.
6S51N has lower amplification (mu=26).

Moby · Sep 24, 2013

Hi, can you compare 13cw4 to vf14?

bezen4uk · Sep 24, 2013

Hi Moby,
I have no 13CW4, but I think it's way different tube. Mu=45..50 at Ip=0.5mA.
7586 and 8393 nuvistors look much closer to VF14.
8393 is especially interesting tube, because it has 60mA heater, so it can work in U47 without mike modifications.

Moby · Sep 29, 2013

bezen4uk said:
Hi Moby,
I have no 13CW4, but I think it's way different tube. Mu=45..50 at Ip=0.5mA.
7586 and 8393 nuvistors look much closer to VF14.
8393 is especially interesting tube, because it has 60mA heater, so it can work in U47 without mike modifications.

Agree, but since it was Neumann's tube replacement I'm really interested to see it. Of course, at same Ip as Vf14

Btw did you test the 7586 & 8393 noise and microphonics vise?

bezen4uk · Sep 29, 2013

Moby said:
Agree, but since it was Neumann's tube replacement I'm really interested to see it. Of course, at same Ip as Vf14 Btw did you test the 7586 & 8393 noise and microphonics vise?

Hi Moby,
I'm interested to test all these VF14 contenders, but it's not fast.
My wishlist : 8393, 13CW4, EF14.
I'll keep adding new tubes to this thread.

There is some update about VF14M:
The tube has extremely low input current at the U47 operation mode - about 30pA!

Moby · Sep 29, 2013

Really interesting, I'm looking forward to it

o3misha · Sep 29, 2013

bezen4uk said:
Moby said:

Agree, but since it was Neumann's tube replacement I'm really interested to see it. Of course, at same Ip as Vf14 Btw did you test the 7586 & 8393 noise and microphonics vise?

Click to expand...

There is some update about VF14M:
The tube has extremely low input current at the U47 operation mode - about 30pA!

Have you measured the emission of this VF14? 0.03ma is too small anode current. Is it noisy?

bezen4uk · Sep 29, 2013

o3misha said:
Have you measured the emission of this VF14? 0.03ma is too small anode current. Is it noisy?

Hi o3misha,
The post was about grid1 input current and it is 30pA (0.03nA).

o3misha · Sep 29, 2013

oops.

sorry. Could you explain why 30 pa input grid 1 current is important? How did you measured this?

Melodeath00 · Sep 30, 2013

bezen4uk said:
Thank you guys for feedback.

There is EF80 characterstic.
Mu=45, while VF14 has mu=28.

So how close if the EF80 to the VF14? Just about all I know is that "mu" is gain, so the EF80 amplifies the signal more? Thanks for the measurements

Measured VF14 characteristic

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