Hi Jim ! Hope all is going well for you! Before my now 150SE's :), I used red base RCA 6sn7's in my VK60. The front two 6sn7's are the input and make the greatest change on the sound.
The 63CCb's also seem to need to be replaced yearly in my system. More dynamics and jump every time I replace them.
Regarding the 6sn7's, They need to be matched and the matched pairs put in spots 1 & 4, then 2 & 5, and finally 3 and 6. Or course these are 6 tubes in the second row. #1 from left to right in my example here.
The RCA's seemed to be smoother on the top end, a little warmer than the stock sovteks.
Also, using 400 - 600 grit sand paper, sanding the tube pins, then using contact cleaner in the tube sockets and the tube pins to me is a big help.
Good luck
The 63CCb's also seem to need to be replaced yearly in my system. More dynamics and jump every time I replace them.
Regarding the 6sn7's, They need to be matched and the matched pairs put in spots 1 & 4, then 2 & 5, and finally 3 and 6. Or course these are 6 tubes in the second row. #1 from left to right in my example here.
The RCA's seemed to be smoother on the top end, a little warmer than the stock sovteks.
Also, using 400 - 600 grit sand paper, sanding the tube pins, then using contact cleaner in the tube sockets and the tube pins to me is a big help.
Good luck