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Design question re: RC network on grids...


 :
3/20/2005 10:57 AM
Roman C. Design question re: RC network on grids...
What are the pro's and con's that weigh in when selecting "larger-value cap and a smaller-value resistor" versus "smaller-value cap and a larger-value resistor" in the networks preceding grids?  
 
Though I'm actually looking for generalities, here's an example so that my question is more clear.  
 
Considering the 5E3, what am I gaining and/or loosing if I change the 0.1 uF & 220k networks feeding the inputs of the 6V6's to something like 0.047 uF & 470k, or 0.022 uF & 1M, etc.  
 
I could guess that higher resistance values would result in more noise, but beyond that, I'm quite clueless as to how the selection is made.
 
3/20/2005 5:04 PM
John Culp

Higher resistance values will also produce more gain.  
 
As for blocking distortion, the time factor of the RC combination is the critical determinant of the time it takes for negative charge in the coupling cap from grid current to leak down. So, keep 'em in proportion.
 

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