U47 with nuvistor separate heater

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Purplenoise

Well-known member
Joined
Sep 19, 2019
Messages
531
Hey guys. I would like to build a “mini u47” using a very small body and a 13cw4 tube. I am trying to avoid the voltage drop 1780 ohm resistor so I was wandering if I can omit it and go directly from psu ( 8-12v line) directly to heater pin of nuvistor without further modification of original u47N schematic.
The psu will be chugers kit used for c12/251 which I believe can provide up to 9v for heater.
Thanks in advance
 
Iam doing the same. So I save up this link. I have a u89 stylebody with a Haufe bv08 and heiserman Hk47 . Iam wondering if I can make it work!
 
Would love to hear some clips when you are done if possible!
Initial tests are very promising…sounds really nice. Very full sounding with great depth. Used the voltage drop resistor for now so I can test it with my 47n psu.
Capsule is Dany Bouchards m7 and transformer 8:1 cinemag cm-2510. Grid resistors 250M
 
The stock PSU has a 9.5VAC winding, which is roughly 12.5V before the regulator. You can easily trim it down to around 10V which leaves plenty of dropout across the regulator even at full heater current.

So yes, I can't see why it wouldn't work.
This is what matador said in his psu thread regarding using his psu on this build.
 
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