I found these by doing a search for "4x12"

http://www.guitartricks.com/forum/showthread.php?t=19794&highlight=4x12

http://www.guitartricks.com/forum/showthread.php?t=18207&highlight=4x12

http://www.guitartricks.com/forum/showthread.php?t=13862&highlight=4x12

http://www.guitartricks.com/forum/showthread.php?t=8374&highlight=4x12

That's just in this forum, do a search in the Tech Talk section as well, if you still don't find what you're looking for. It really is that easy. Nobody's trying to discourage new members from asking advice. We just try to encourage all members to use the search feature first, and then ask questions later. This keeps members who have been here a while from having to keep repeating themselfs over and over again.