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previous: Doc According to your measurements, 13.... -- 11/11/1999 3:51 PM View Thread

Re: rectifier in homebrew ac-30 TB...

11/11/1999 5:31 PM
Bob S.
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Re: rectifier in homebrew ac-30 TB...
Your plate voltage is way to high. First you need to zener down your B+ voltage to a least 360 volts and then you'll see about 348 volts on the plates which is a lot easier on EL-84's. Your ma. per tube should be about 38-40 ma.  
 
These designs will run warm but they will last for years like this. Vox AC-30's have done it for 40 years.  
 
Now if you can't put in a zener diode the next best thing would be to lower the screen voltage so that it would be 20-30 volts below the plate voltage. This will govern the tubes aand keep the high voltage from blowing up the tubes. You might try something like 2700 ohms on the screens.  
 
As far as your V-30's blowing up, I wouldn't worry about them. That amp can't blow up those speakers. That amp running like screaming dog can't put out much more than 50 watts no matter how you drive it and V-30's are rated a 60 watts each.  
 
Bob @ DynaQamps