Which of these tubes should I purchase for my BAT amp? 6C33C-B or 6C33C/6S33S?

The 6C33C-B and the 6C33S-V is the exact same tube. Different translations of Russian. Check out this page and that page. The 6C18C is an older equivalent - not as good. Many factories made the 6C33C-B tube back in the day.

I’m pretty sure that I purchased the ones from the Ulyanovsk factory. Bought them from Russian and Ukraine sellers with 100% positive feedback. Never had a problem. Allow 6-8 weeks for standard economy delivery.

As with many Ebay sellers, different prices for the exact same item. I paid around $20/tube plus shipping. It appears that the prices have skyrocketed then.

Visit this site for more in-depth info. Interesting photos of the tube in the guidance system of a Russian cruise missile. Unfortunately, it was aimed at us.

Thanks for your input.  One of the Russian e-bayers has a quad set for $99 and free shipping.  He has 100% feedback (has many satisfied 6C33C custormers) with 14 day return and the tubes are from the Ulyanovsk factory.

That’s a great deal! I always purchased a couple of extra tubes just in case any were DOA. They never broke during shipping but sometimes there might be a bad one - just like any untested batch of tubes.  The ones I bought arrived in sealed boxes.  Even if all worked fine, it never hurt to have extras. The seller probably can add more if you wish. Enjoy!

That's good advice-thanks.

Hello yenkochris and steakster,  This is a most helpful post since I have a BAT VK-60 and it appears like it's time for new power tubes, at least.  Did everything work out well with the Russian ebay-er?  If so, may I ask what his/her handle is?  Thank you.