Here is some tube porn for the evening. My friend Chris dropped this 1938 RCA manual by today. It is amazing and the tube diagrams are beautiful. It is a little fragile so I didn't flatten the pages to get the images.
“I like big horns and I cannot lie, those little horns make me cry” Tom Danley "Simple. A horn is just a reasonably rigid boundary for an air column. Now all you have to do is figure what shape to make it." PWK