I did not even know that there are different types of EL 34 tubes. A good friend brought over to my place various quads of vintage EL 34 and 6CA7 (1950s and 1960s) tubes. I got to pick out which quad to keep as a gift to use in my BHSE. I chose a quad of Telefunken tubes.
What is the difference between EL34 A,B,C, or PH tubes.
Will any EL34 tubes fit in the BHSE?