Tube Amps / Music Electronics
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|5/28/2000 4:39 AM|
||Power Supply Advice Needed|
I just wired up a Hammond 270FX power transformer that was supposed to be 275-0-275 @ 150 milliamps with 6.3V center-tapped and 5V taps. With my line voltage I'm getting 313V on each secondary tap and 7.1V across the 6.3V taps. I'm getting 5.5V across the 5V taps that are wired to a 5AR4 rectifier. I was hoping to use this to power a 2xEL84 amp at approximately 350V for the B+ but now I'm getting in excess of 420V at the first 50uf cap after the rectifier (with no load). My questions are:
What to do about the excess voltage? I could use a choke input filter and drop the B+ to about 275V (with SS rectification). How does a choke input filter affect the sound? I'm using an UL OT so better regulation for the OT might be good. Also, I've heard that EL84's really sound better at voltages lower than 300. Any truth to this?
Will the high filament voltages cause me any problem? I'll be running 2 preamp tubes and 2 EL84's off the 6.3V taps. How much drop will I get from the 7.1V I'm getting right now?
Should I just scrap the Hammond and buy a PT that is designed to work on higher primary voltages? If so, what would you recommend?
Any advice on how to proceed is much appreciated.
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