WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
I purchased a pair of 5691 black base tubes and was wondering if there is any difference between the black base and the red base other than the color of the bases. The black base also has the vertical support bars like the 5691 red base does.
The only thing I know is RCA made red bases and rebadged them for other companies like GE
whlie sylvania and others made them with brown bases and supposedly the same but I don't
about black what brand is it ? They should all be special quality 10000 hr and closely matched sections and such.
I've had a few of these and because of the black base they are usually inexpensive. My understanding is they were made in the last couple of years of production possibly by Sylvania, but I'm not sure as to who actually made them now.. It was long ago. They sounded fine.