6SN7 tube GTA vrs GTB

I would like to know the difference between the designation GTA and GTB.

Thanks

fordmod07-04-2008 3:14pm

jsman Details Discussions Posts This discussion Message User 246 posts 07-11-2008 at 02:12am Copy Comment URL Report Comment Edit Delete I use Sylvania GT's and the ones known as (Bad Boys)in my pre. I can not find better.