U47 with Phaedrus VF14 M tube

[oscarhuang]

I love EF800 tube U47. Then I did some research and I found Phaedrus audio VF14 M electric tube. Unfortunately I can’t afford the real VF14 M tube. Someone told me that tube is really really important for the sound . Because of this is a electronic tube you don’t have to wait for the tube to warm up and almost not life limit. I sent it to my friend who have the original U47 to compare those two tubes. It’s hard to describe the sound but he said it is around 70% to the original VF14 tube. For me it’s cleaner and faster than EF800. EF800 has more tube harmonic. Here are some photos

 

[Recording Engineer]

Cleaner? Faster? That’s what I say too. I still haven’t yet, but maybe I should try it in front of the kick, like most would with a 47FET. Mine is with a K47 capsule though.

 

[RuudNL]

The Phaedrus electronic tube has a significant lower distortion than the 'real' tube.
(The 'real' tube has mostly second harmonic distortion.)

 

[kingkorg]

I love EF800 tube U47. Then I did some research and I found Phaedrus audio VF14 M electric tube. Unfortunately I can’t afford the real VF14 M tube. Someone told me that tube is really really important for the sound . Because of this is a electronic tube you don’t have to wait for the tube to warm up and almost not life limit. I sent it to my friend who have the original U47 to compare those two tubes. It’s hard to describe the sound but he said it is around 70% to the original VF14 tube. For me it’s cleaner and faster than EF800. EF800 has more tube harmonic. Here are some photos
View attachment 90494

Maybe you could inject some signal into the grid at different levels, do some sweeps so we can see the harmonic profile of the tube, frequency response, and put a finger on what cleaner, and faster actually means.

 

[craigmorris74]

Maybe you could inject some signal into the grid at different levels, do some sweeps so we can see the harmonic profile of the tube, frequency response, and put a finger on what cleaner, and faster actually means.

That would be awesome, because I'm torn between the EF800 and Phaedrus device.

 

[kingkorg]

Fwiw i ended up using EF14.

 

[craigmorris74]

Fwiw i ended up using EF14.

Have you ever had the chance to compare it to an EF800 build? If so, what differences did you hear?

 

[kingkorg]

To be honest i could never do as extensive and detailed research than this one Milan did. His credidentials are way to impressive (being familiar with Yugoslavian history) for me to question anything he has done. So i just went with EF14 and never looked back. Never had an issue with microphonics either. Not sure if he made any direct EF800 comparison. There are parts one and two just so you know. You can drop him a dm, he is called @moamps here.

http://www.moxtone.com/mU47_U47_part3.html

 

[Gus]

Should I release my circuits?

 

[abbey road d enfer]

It’s hard to describe the sound but he said it is around 70% to the original VF14 tube.

Measured with what? Is it really 70, or could it be 69 or 71?

 

[kingkorg]

Should I release my circuits?

Well you know how i feel about them. I am sure they would be widely adopted, an possibly way too widely.

 

[peterc]

Should I release my circuits?

Do you have a SS alternative to a VF14 or something similar?
Would love to see something like that.....
Thx Peter

 

[oscarhuang]

Should I release my circuits?

Welcome

 

[fazer]

Please release. I worked in a studio that had 2 u47’s. One had a VF14 and one had the nuvistor. The VF14 was magnificent and the 6cw nuvistor was no comparison in depth of field and fullness of aound. There was a VF14 tube for $1000 awhile back. If it’s a good tube it’s worth it. IMO

 

[LevinGuitar]

Should I release my circuits?

Different biasing?

To be honest i could never do as extensive and detailed research than this one Milan did. His credidentials are way to impressive (being familiar with Yugoslavian history) for me to question anything he has done. So i just went with EF14 and never looked back. Never had an issue with microphonics either. Not sure if he made any direct EF800 comparison. There are parts one and two just so you know. You can drop him a dm, he is called @moamps here.

http://www.moxtone.com/mU47_U47_part3.html

Did you used Ami way of biasing?

http://www.tab-funkenwerk.org/wp-content/uploads/2019/09/U47ArchutAltTubewithRemote.jpg

 

[kingkorg]

Yes. Keep in mind heater supply has to be super clean.

 

[LevinGuitar]

I'm stuck there, just some resistors+caps to ground in the way?

 

[oscarhuang]

I'm stuck there, just some resistors+caps to ground in the way?

Yes. Some of 10000uf caps and resistor to get the voltages.

 

[kingkorg]

I'm stuck there, just some resistors+caps to ground in the way?

Try a cap across R3, as large as possible if you have issues with hum.

 

[LevinGuitar]

Already tried big caps there and it helps a lot but would need to improve my psu. Thank both!