Quote:
Originally Posted by Boogie
My other tube amps do not do this, only the SFDR. My DRRI (recently sold) and Boogie Mark IV behave the same after 60 minutes as they did after 60 seconds. Ditto with both of my Twins, although they don't get much stage use so it's possible that my SFTR may be the same way.
|
I would count that as (possibly) empirical evidence that the old resistors in your SFDR are the culprits.
I replaced all the important resistors in my '65 BFDR long ago with much higher grade components with better temperature ratings. The result is a very stable amp that is quiet and consistent.