Hope this is OK with Stephen
here's a link where some guys more knowledgeable than I talk about different values for the ef86 stage.They are pretty similar to the tc-15 values
http://music-electronics-forum.com/t907/
here are some more ideas from another forum
Quote:
From the plate, start with .0022uF/630v and a cathode bypass of only 4 or 5uF/25v. You'll be amazed how much bass that can produce. Just a suggestion for a starting point. Don't go too big on screen bypass caps, max value is around .1uF/400V no matter the pentode. Start with .047 or .01uF/400V and then go up or down and hear what the changes do. Some guys wire in trimmer pots to adjust screen values
I would be interested in any findings or experiments.