NOS RFT EL34's manufactured in the early 60'

[FourT6and2]

Oh forgot to mention, that I always swap the grid leak resistors with 100k in the 4-cyl. 100 watts models and use a strong ECC83 in the PI spot, usually a Yugo EI or a smooth plate Telefunken.

That makes sense. I sometimes go with 150K + 10K grid stoppers. I love those Ei Yugo tubes, but I haven't been able to find any that haven't been microphonic. Ever lol.