From: eikelan@gmx.net   
      
   G.Re wrote:   
   >  Hi folks,   
   >   
   >  What is the reason the Fisher 30-A uses (very) different valued grid   
   >  resistors for the power tubes?   
   >  - R9 = 2K2 for V2   
   >  - R4 = 33K for V3   
   >  https://www.flickr.com/photos/derekva/7211152916/in/photostream/   
   >   
   >  A later (or earlier?) 30-A version has no grid resistors,  also no balance   
   >  circuit for the phase inverter.   
   >   
   When the EL84 start pulling grid current the difference of   
   impedance of the cathode side and the anode side of the phase   
   splitter comes into play. To balance the grid current the anode   
   side grid resistor is of lower value than the cathode side   
   resistor. That is careful design. The engineers probably found   
   out that, for consumer grade equipment, the distortion due to this   
   effect are negligable compared to the the distortion due to   
   overload and canceled the resistors to save some cents.   
   Kind regards, Eike   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)