Effect of Tube shape?

[debk]

I am curious.  Looking at different 300b's and some other tubes, they are made with different shaped glass envelopes.

What effect does the envelope shape have on the tube?

Thanks

Debra

[2wo]

I have globe mesh plate 300B and 45's. I think they look cool. There is some talk that the ST version of the 300B is slightly less microphoneic. the mica is smaller and slides into the straight sided top segment.  I have not had problems with mine...John     

[Doc B.]

Yeah, in general ST (shouldered) shaped envelopes have structural differences inside that should make the tube less microphonic. But you really have to smoke it and see.