RCA 6SN7’s Question?

Toolfan66 Posts: 16,267
So I purchased this lot of NOS RCA 6SN7GTB’s
9 of them look a little different, the base is shorter, the diameter is about 1.45, and there is a hair thin wire you can see going across the top.

The other 4 of them have a taller base, diameter is about 1.65, and no hair wire going across the top.

Outside that the build between the two look the same.

Different manufacturers?

I actually like the look of the taller wider base, but not like you will see them.

What do you Tube guru/nerds think?



  • pitdogg2
    pitdogg2 Posts: 23,789
    I have a pair of both those tubes. GE made tubes like that top filament. The RCA flashes at start up, the GE stays red hot as long as the tube is on. GE calls theirs "bridged filament" .
    The bases did change to the shorter style on all after a point in time. Usually the taller base is older tube.
    RCA made many styles across years and decades. My personal opinion is both are RCA made tubes.
  • Toolfan66
    Toolfan66 Posts: 16,267
    Ha, filament was the word I was looking for, thanks Ivan, hopefully I can give a few of these a shot this weekend..