01-26-2009, 07:19 PM
The XXL is a 14AF7. It is a loctal 12SN7. There was also a 7AF7 which is roughly equal to a 6SN7. The ubiquitous dual medium mu triodes, they behave as a "modern" 12AU7. This is a re-post, as my original message did not go through. Is this what you were interested in?