I have an Ameritron AL-572 that I have had very good success with. I know a lot of people don't like the Ameritron products or the 572, but I have had great success with both. I do agree that the 813 is a tougher tube. Rick Jack Schmidling wrote: > > Just thought I would ask as I never hear anyone using 572's for > anything other than my amp. > > js >