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Re: Chassis ping


 :
6/5/2000 10:37 PM
Ric Re: Chassis ping
Ken, great suggestion.  
The pre amp set-up I'm using is two 12ax7.  
Pre using 1/2 the first tube,  
Tone stack feeding vol. pot  
Center pin feeds a resistor to the  
First gain stage.  
Second gain stage.  
When I clip on to the grid side of the resistor of the first gain stage the amp turns into a AM radio. When I clip onto the pot side it hums but no microphonic. You can hear signal, plug in guitar and play, but it's very muffled.  
Do you think there's a problem having three pins on that first tube goin' no where?  
I've tried replacing the pot and the resistor but no luck.  
This seems to me like a gain problem.
 
6/6/2000 11:02 AM
Peter S

Ric,  
Tie the 3 unused pins together......better yet, parallel the two halves of the 12ax7 for a fatter tone. Just remember to adjust your resistor values accordingly.  
 
Peter S  
Kimerik Amps
 

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