Nutella's link is my favorite...
Owning a BC21 myself for many years (and currently in my secondary system) my favorites are...not in any order...
Tung-Sol VT-231
Ken-Rad VT-231
Sylvania 6sn7W (short bottle).
Dennis Boyle's descriptions on that website are very accurate to my ears...
Owning a BC21 myself for many years (and currently in my secondary system) my favorites are...not in any order...
Tung-Sol VT-231
Ken-Rad VT-231
Sylvania 6sn7W (short bottle).
Dennis Boyle's descriptions on that website are very accurate to my ears...