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previous: frankenstein Bruce: Thanks for your response. I ... -- 3/17/2002 5:32 PM View Thread

Re: need more headroom

3/17/2002 6:04 PM
Bruce /Mission Amps
Re: need more headroom
"I originally obtained blackface deluxe PT but decided that would be too high voltage... even with zenner to drop it 50v ... Now I'm wondering... I was expecting 350v DC at the plates..."
Yes that's a common misconception. Using a NOS 5Y3 will drop the plate voltage considerably.  
My Soulkicker amp runs a similar PT, as does the 5E3 project amp, and most guys are reporting back the B+ running around 350vdc to 370vdc.  
You should try using a SOVTEK 5Y3 now... it is much stiffer then a NOS 5Y3 and you should see a nice jump in B+. If that is not enough, try a SOVTEK 5AR4.  
If when using either of the stiffer recitifier tubes the B+ gets up there higher, like our 5E3 project amp, consider using a 270 ohm biasing resistor instead of the 250 ohm one.  
Don't be afraid of the B+ going as high as 380vdc (as measured to ground, not to the 6V6 cathodes). Bruce

frankenstein Good Man Bruce !I wish I'd talk... -- 3/17/2002 7:18 PM