New in original boxes, the only version of EL34 that EI factory ever made. 6CA7 was also made in Nis, Serbia but in bigger glass envelope of PL509/PL519 tubes. For this EL34, PL36 /EL36 socket and PL36 glass envelope is used. Disc getter and three holes in plates. A lot of these tubes were very problematic, more than 60% of regular production was under dissipation ratings, but some rare examples, carefully tested are great, sonicaly and by dissipation. I have two batches, one is year 1987 and another is 1988.
Perfectly matched quad, within 5%!
This is killer EL34 to any new production like JJ, Electro-Harmonix, Genalex-Gold Lion, Svetlana, Mullard, Shuguang, Tung-Sol, … EL34 6CA7 KT77.
They have been made in 80s, when EI factory has made million of tubes on monthly basis with strict quality control, tubes were printed depends on order, for many world famous tube brands like Siemens, Philips, Telefunken, RCA, Marshal, Jadis, Valvo, RTC, …