Univox U-1226

[stereomonostereo]

Hey guys

I'm working on a Univox U-1226 and i've got a few questions. The amp is running the plates of the 6L6GC's at 660v, which then gets dropped to 325v on the grid. It's well beyond spec for a 6L6GC, but with the grid running around 325v it's a bit less stress on the tube. One of the filter cap values is 60uF @ 450v, but the amp is running 660v at that point as well. My questions are, do i need to beef up the voltage on the filter cap? Would i be better off reworking the amp down to something like 400v on the plates? Why would the engineer want to run the plates that high over spec?

[52 Bill]

...One of the filter cap values is 60uF @ 450v, but the amp is running 660v at that point as well. My questions are, do i need to beef up the voltage on the filter cap?

There shouldn't be more than about 330 volts across that cap, it's a voltage doubler so each cap will have about half of the total supply voltage.

I've seen that amp before, but it was back in the days of US made tubes. I don't know why the ultra high plate voltages. Probably to get more power and headroom.

[Enzo]

What Bill said. There may be 660v ON that cap, but not ACROSS the cap. Caps care about the voltage from end to end. They don't care at all what the voltage might be to ground, unless they are connected to ground.