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V-4 Bias mod

8/3/2000 7:03 PM
Tom L
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V-4 Bias mod
Sometime back in July, Graywater wrote:  
 
quote:
"I've got a V-4 I'm adding a bias pot to but it has the V-4B type "pie" bias filter setup. While I suspect that you have a V-4(non B)based on Ray's suggestion, the V-4B only requires replacing the 10k resistor (R60) with a variable one. I'm going to use a 20k, 10-turn pot in series with a fixed resistor. I'll start with 5K and play with it until I'm satisfied. "
 
 
On closer inspection, I see that my amp does have the V-4B type of bias circuit (even though it's a V-4, not a V-4B--I should have noticed this before I did the mod!). So I need to take out the trimmer I put in at R49 and put one in at R60 like you did.  
 
So, what values did you finally come up with for your mod? And did you wire the trimmer as a pot or a rheostat?  
 
Thanks for being patient with me while I learn.  
 
--Tom

 
Replies:
Graywater Tom,You must have n... -- 8/3/2000 7:23 PM