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Re: Cooling down a BadCat

5/20/2003 5:31 PM
PhilipMorrison
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Re: Cooling down a BadCat
Guys  
 
I agree with the consensus(easy huh?). On a similar amp, using similar trannies, I dropped in an extra filter node for the screens as well as changing the bias resistor & it seems to have done the job pretty well.  
 
Having already upped the cathode bias resistor to 150 ohms, you may want to try an extra filter node made up of say a 4K7 2 watt resistor & a 22uf cap. & leave the 100r's alone. Depending on where you take the node off from you should be able to get that screen voltage under 300 and reduce the screen current enough to cool it off.  
 
In my experience, with that rig, I end up somewhere around 33-38ma per tube at around 360vdc on the plates. I make it around 12 watts per tube instead of 16-17. You will lose some of that famous headroom & clarity though.  
 
Philip Morrison