Tube Amp connections : 0V vs EARTH vs HEAT vs CURRENT

[merlin]

Any prediction on timeline?
Curious if there is a one line description of what you found needed updating. I would think that there isn't much changing in the world of tube designs these days.

I'm hoping to get it out later this year, keep an eye on my website for any update. There isn't much that changes in the world of valves, but there are always changes that can be made to my books! This one is getting quite an overhaul, with less useful stuff removed and whole new chapters on new subjects added...