Hello. First question: I have read on the internet that the four tubes put into the Eclipse do not need to be closely matched, as the circuit is self-biasing. Is this correct? Would it be important for the two tubes on the left side (the entry tubes) to be a matched pair, as they are more important than the right hand tubes (exit tubes)?
I am asking because it is much more difficult to find a matched quad of NOS / vintage tubes. However, it is easier to find either two matched pairs, or four unmatched individual tubes.
My second question: last year I changed the stock tubes to two Brimar 6067 ECC802S 'T' (the entry tubes), and two Pinnacle 13D5A (the exit tubes). However, I would like to see how much the sonic character of the Eclipse changes with tube rolling. Does the sound of the Eclipse really change very much with different tubes? If so, can anyone suggest which vintage / NOS tubes would be worth trying next? I have read that Amperex 7316 tubes are excellent, but they are very expensive. A less expensive option appears to be the RCA clear top 12AU7A, or the Westinghouse 12AU7 with the carbonised plates from the 1950s.
Any suggestions would be welcome. Would it be worth moving the two Brimar 6067 ECC802S 'T' tubes to the right hand side (as the exit tubes), and use something different in the left side (entry tubes)?