From: phil_a@tpg.com.au   
      
   "John L Stewart"   
   > 'Phil Allison   
   >>   
   > >   
   >> > 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.   
   >>   
   >   
   > There was an article on 2H cancellation in SE amps published about 10   
   > years ago, I think in Glass Audio. Used the curvature of the driver to   
   > cancel curvature in the OP Tride. One would think this possible at only   
   > one level on the output.   
      
   ** More testing with the FFT feature on a Rigol scope:   
      
   3H is dominant from about 9 watts through to 21 watts.   
      
   From 1watt to 4 watts, 2H dominates, then 4H, then 3H.   
      
   If load R is changed to 16 ohms, 2H dominates all the way.   
      
   2H cancellation is occurring over a fairly wide range, but it is not   
   complete.   
      
   I can swap the 6SN7 with almost no change.   
      
   Neat eh ?   
      
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)