Tubes Asylum

RE: 6CG7/6FQ7 - with wiring changes.

50.158.12.17

kkak66

In Reply to: RE: 6CG7/6FQ7 - with wiring changes. posted by Chip647 on September 13, 2014 at 16:54:49

No the pre amp is not made in China. Look up TomCat Audio. He is out of California , and makes his design amps and pre amps hand made bye him, with quality parts. Just Google him, you will find info. Then get back to me.....Don,t just assume it's Chinese.

Follow Ups:

RE: 6CG7/6FQ7 - with wiring changes. - Tre' 13:26:09 09/14/14 (3)
I can't find a website for John other than his Facebook page.
Maybe someone could call him and ask how the circuit can be right for each of the suggested tubes.
Normally when the supply voltage, plate load impedance and cathode resistor values are right for one tube, they will be wrong for any other.
310-985-5765
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
- https://www.facebook.com/tomcataudio (Open in New Window)
Edits: 09/14/14
- RE: 6CG7/6FQ7 - with wiring changes. - kkak66 14:36:34 09/14/14 (2)
  The tubes are self biasing according. To John. I ordered one of his pre amps. They have pics on his FB page.
  - RE: 6CG7/6FQ7 - with wiring changes. - Chip647 17:33:50 09/14/14 (1)
    I don't use Facebook.
    
    FYI
    "Self Biasing" means simply that there is a cathode resistor. If he is using a CCS as the cathode load, it will be set for one current draw. Running a 12AU7 at 1mA (what a 12AX7 typically uses) kind of misses the point of a tube that wants to use more than 10mA.
    
    A 12AU7 has a gain or Mu of 17 or 18, a 12AX7 has a Mu of 100. Unless there is massive feedback or they are just cathode followers, there is no way the tubes could be interchangeable.
    
    I am sure Tom is nice and everything.
    - RE: 6CG7/6FQ7 - with wiring changes. - kkak66 17:50:29 09/14/14 (0)
      I really don,t know much about his design but I did order one of his pre amps. I am sure he knows what he is doing I hope. Thanks for the info. He uses 4 tubes in pre maybe if I just use all 5814 or 12au7 it will be ok.

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