All of the tube amp designs i see have the tubes exposed to air. Is this a design feature for heat dissipation or is it simply because some find it pretty?
1\$\begingroup\$ Ah, (1) Tubes are hot! (2) Tubes are pretty. \$\endgroup\$– tlfong01Jan 5, 2021 at 8:17
1\$\begingroup\$ @tlfong01 Or, alternatively, if you really like vacuum tubes: (1) Tubes are hot! (2) Tubes are hot! \$\endgroup\$– KroltanJan 5, 2021 at 18:59
It is for heat dissipation. And tubes get hot due to the current flowing through them. It's the work they do that makes them hot, rather than that pretty glowing filament as you might expect.
Having said that, look up tube shield. These are metal cans that fit over the tube. They are used as electrostatic shields in the same way as shielding over other electronic components. These shields usually are in contact with the glass so they can absorb the heat and radiate it themselves.
2\$\begingroup\$ The tube shields I've seen are not precision fitted to the (also not precision) glass envelope, there is some clearance. (They fit to a bayonet style connection on the socket). \$\endgroup\$ Jan 5, 2021 at 16:53