From: phil_a@tpg.com.au   
      
   "flipper"   
    "Phil Allison"   
   >   
   >>> UBT-1 is rated at 160mA on the primary...   
   >>   
   >>   
   >>** Yep -  the total idle current is 110mA.   
   >>   
   >>   
   >>> Did those 300Bs develope a dead short?   
   >>   
   >>   
   >>** According to the owner/builder -  there was a flash / bang / wallop   
   >>event   
   >>and then a dead channel.   
   >>   
   >>One dud 300B draws no bias current while the other draws waaaay to much,   
   >>the   
   >>UBT-1 has an open deep inside but shows no sign of shorted turns.   
   >>   
   >>What has me intrigued, however, is the low THD figures at and near full   
   >>power PLUS the fact that 3H dominates.   
   >>   
   >>The test results are far more like a PP class A triode amp than a SE one.   
   >>   
   >>The 6SN7 is running at full gain ( about 18 times per half ) and there is   
   >>definitely NO negative feed back - in fact the two speaker windings have   
   >>been left floating.   
   >>   
   >>   
   >   
   > Sounds like by either intent or serendipity the 300B and 6SN7 2'nd   
   > harmonics are canceling.   
      
      
   ** Bingo  !!   
      
   Seems an eccentric Russian gent was responsible for the circuit design.   
      
   The owner has agreed to purchase another UBT-1 from the USA and new 300Bs   
   and send them to me.   
      
   Then I can hook the beast up to my own speakers ( 10 inch 3 ways plus active   
   sub ) for a listen.   
      
      
      
   .....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)