After spending too many years playing Russian Roulette with Sovtek, Svetlana and Winged-C tubes (and their many re-brands) I’m pleased to announce that I now deal exclusively with Bob Pletka at Eurotubes. Over the last few years I have requested that my customers purchase tubes from Bob when bringing me an amplifier for repair or maintenance
You may ask why ?
First, because he does proper testing of their tubes, the way I would do it : in “all” modes. I grilled him extensively about this many years ago // proof that he knows what he’s doing shows on the bench when I do my in-amp testing over the course of a few hard-driving days. Yes, I beat the living daylight out of new power tubes (… and re-test for any sign of drift) before returning an amplifier
Second, I have not yet once seen an amplifier come back to me because a JJ tube suddenly crapped out or drifted radically out of spec, which is not something I can say about the other stuff. In private conversation with Eric Barbour he agreed that the JJ KT77 (with hand-aligned Screen Grid) and JJ E34L, are likely the most reliable EL34’s on the market today