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previous: PeteRH I am planning to build an amp with ... -- 4/16/2003 1:37 PM View Thread

Re: Different voltages from the one tapped transformer

4/17/2003 2:17 AM
John Culp
Re: Different voltages from the one tapped transformer
Pete, why do you want 400V on the preamp? 12AX7s are rarely run over 300v plate supply. Seems like 330V's the official maximum. No doubt they can be run higher, but it seems as though they'd work fine at the voltage you're going to run your EL84s on, or a little less if you follow the udsual power supply topology with a decoupling/dropping resistor and filter cap after the power tubes' plate and screen supplies.  
That is way more DC capacity than you'll be using from the tranny, meaning the output voltage will be somewhat higher than the rated value as well. Output voltage is normally given at the full rated output. You might end up with 475V or some such. Of course, you can add resistance in series with the rectifiers to drop that.

PeteRH Hi JohnMy express clone (or wha... -- 4/17/2003 9:04 AM