I don't have any recommendations, but be careful with some of these newer 300B tubes. Some of them draw a lot more amperage for their filaments, than the real original 300B design tube did. Some have other specs that may not work in your amp either. A lot of amps can't handle some of the new 300B tubes. If you find a new tube that draws more than 1.2 filament amps, check to find out if your amp can run them.
I guess they don't have standards like they did in the tube only days. I think these new (different spec) 300B tubes should have a different number, since they are different. Just a heads-up. A link to an article about this. [http://www.stereophile.com/features/229]
I guess they don't have standards like they did in the tube only days. I think these new (different spec) 300B tubes should have a different number, since they are different. Just a heads-up. A link to an article about this. [http://www.stereophile.com/features/229]