U47 Low Noise tube alternative

[Spencerleehorton]

Hi Guys,

wanted to start a thread just about possible alternatives to the VF-14 and EF-14 valves for use in the U47 tube mic.
I have also been looking at the following and wondered whether anyone else had tried them in the U47 circuit, or any other circuit.

ME1400
EF37A
EF80
EF86
EF42
EF174
UF174

if anyone could put forward any info on what mics these are good or bad for.

regards

Spence.

 

[Gus]

The best thing to do is buy tubes and try them.  This is what I did building a number of tube circuits.  It is good to understand something about how tubes work.

You might get some answers but remember this is the web and the answers are free.

 

[Spencerleehorton]

Hi,

I did read somewhere that using the EF86 makes a U47 way to middle heavy, Is anyone able to verify this?
Also is anyone able to shed some light onto why this would take place?
I am thinking about going the 2 tubes in parallel route but still not 100% on what tubes.
6028 seem the way to go or 408A?

Let me know what you guys think.

regards

Spence.

 

[ioaudio]

Bernd, are you 100% sure that Andreas is OK with you posting this in public?

 

[benqbasic]

Bernd, are you 100% sure that Andreas is OK with you posting this in public?

Was wondering this myself as the only copy floating around is not that readable.

 

[bernbrue]

Well, deleted the post, but it was floating around here somewhere.

 

[mabell313]

Fox Audio has a great article about using a paralleled 6922 as a U47 alternative tube. Said article is based on an Apex 460 circuit (which is the same circuit in a Nady TCM1050 which has a U47 shape about it). The tests were all done through a stock Apex 460 4.5:1 transformer none the less! Very impressive response curves. More like, lack there of! The response was dead flat with a low bass boost(20 Hz). Exactly what you want from a U47 style circuit. Check it out.

 

[ioaudio]

Bernd, hope you don't take it the wrong way. Looks like i feel a little protective for A.G.

-max

 

[Spencerleehorton]

will check that out, thanks very much.

regards

spence.

 

[VanGenz]

EF800 could also be used. Still quite cheap. Have not tried it.

 

[Spencerleehorton]

Would be interested in how the EF800 compares if anyone has any info.
but like you say still cheap around £15 each

regards

Spence,

 

[zebra50]

A few people here have tried that tube. A search for ef800 gives a few threads!

 

[gyraf]

To my ears, the EF42 is the one sounding closest to VF14, when underheated and in G7 setup.

However, that tube has massive problems with microphonics.

Jakob E.

 

[gyraf]

Telefunken EF14's are also decent - here's a Danish guy selling a couple of them at DKK375 each (ca 68 usd)

http://ham.brugtgrej.dk/annonce/94423

I've gotten tubes from him before, seems legit.

Jakob E.