which EL 34 for VTL 225s?

A buddy of mine who owns VTL 225s recently had a tube failure. He was told that the 225s shouldn't use the Tesla EL 34 tubes.

Anyone know anything about this? I know the amp has used these tubes for at least four years, probably longer.

Does anyone have a recommnedation? Cost should be a factor because there are 16 tubes.

Thanks for info.
I just sold my 225's. I used Electro-Harmonix EL34's with great success. They are reasonably priced.
I don't know why Tesla's would have a problem, but, from time to time, I did have a tube fail or a fuse would blow.
Should I assume your friend is biasing the amps properly? Was it one tube failure, or all?
By the way, I didn't sell them because I didn't like them. They are terrific amps.
EH tubz are less durable and need replacements more freequent so there's no savings there.
Teslas are much more durable but bass is much thinner than with EH.
Svetlanas are excellent tubes on durability, acceptable bass and great midrange.
EI34 fatboys combine all of EH and Svetlanas positives thus I do recommend them.