For the pentodes the EL34 metal base have the best resolution and cleanest sound. There is little difference between the 6CA7 big bottle (Philips ECG or Sylvania only).
BTW: Siemens never produced any EL34.
You might also try to play with the 6CG7 and the 6BH6.
I use Philips labelled 6CG7 (D-Getter) from the 50's.
I'm currently try to find Philips E90F (=6BH6), mesh plates
BTW: Siemens never produced any EL34.
You might also try to play with the 6CG7 and the 6BH6.
I use Philips labelled 6CG7 (D-Getter) from the 50's.
I'm currently try to find Philips E90F (=6BH6), mesh plates