On September 7, 2014 at 23:50, Ernie Gilman said...
The aluminum tube covers are shields. Tube grids are where the signal is put into the tube, so they're not extra. They could be screen grids, though, which I believe were grounded or held at some other DC potential (ground is a DC potential of zero).
Marantz had such a line. Its brand was Imperial and its front panel had -- woo woo! -- backlit magenta lettering.
I know they're shields and I know the top grid isn't really 'extra', but since noval tube sockets weren't being used at that time, I meant that it's extra WRT octal sockets. I also know 'ground' is zero potential difference.
Magenta- early '80s? That would be the same time Sony had TV colors like mauve, taupe and teal.
