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Caps on tube grids - Fender Deluxe


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12/12/1997 1:39 PM
Steve Watson
Caps on tube grids - Fender Deluxe
I was reading in some Fender amp books about the silverface Deluxe Reverbs having a (not sure if I have this right) 1200pf cap attached to the tube grid and going to ground to cure some instability, with resulting loss in the treble response.  
Can one of you gurus tell me what would be the pros and cons of removing these, or if it's even possible? Naturally, I wouldn't be doing this myself, since I know jack about the guts of a amp.  
Thanks in advancefor all responses!  
 
Steve  
 
Swatson@loyola.edu
 
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12/12/1997 2:31 PM
John Greene

My 74 had them, I snipped them out. It makes a big difference and is well worth doing. I didn't have any adverse side effects but I have read that there may be some trouble with high-frequency oscillation if you remove them. If so, you may have to move the signal wires connected to the grids around or use shielded wire.  
 
There are also a few other changes you may want to make while you're having someone in there taking the caps out. If the plate resistors connected to the phase splitter are 47K's, change them to a 100K and 82K. Change the grid resistors on the phase splitter from 330Ks to 1Megs. And last but not least, change the coupling cap to the phase splitter from a .01uF to a .001uF. This really makes a difference in the tone of the amp.  
 
--johng
 

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