From: phil_a@tpg.com.au   
      
   "Patrick Turneroid"   
      
      
   ** More info:   
      
   In order to find the " open loop " THD of a Quad II output stage, I   
   removed the two EF86s and connected an output tranny primary to   
   the + supply and both plate pins.   
      
   The secondary was then driven by my bench oscillator, which has   
   very low THD -  circa 0.002%.   
      
   This gave 52Vrms from grid to grid on the output valves - enough to   
   drive the stage to 10 W at 8 ohms and 1kHz.   
      
   Results:  THD =  0.76%,   DF = 1.   
      
   ***This is all to be expected   
      
      
   ** You bullshitting asshole !!   
      
   You had no idea what the THD figure was  *open loop*  !!!.   
      
      
   Also tried were Electro-Harmonix and GE 6L6GCs with closely similar   
   results, the EHs producing 0.8% and the GEs about 0.7%.   
      
   ***Typical expected results.   
      
      
   ** You bullshitting ASSHOLE !!   
      
   You had no idea what the THD figures for those tubes really were.   
      
   I only mentioned them to show the THD result was easily repeatable.   
      
      
   With EF86s restored to their sockets and the OP tranny removed,  THD   
   dropped to 0.036% ( 10W, 8ohms) and DF improved to a respectable 10.   
      
   My conclusion is that the two EF86s reduce the THD of the output stage in   
   line with the level of NFB being used ( ie 26dB ) while adding virtually   
   *NONE* of their own.   
      
   ***OK, I agree with your 26dB. I'd have to check my notebooks to see if I   
   ever measured 0.036% at 10Watts, but I cannot now recall ever seeing THD   
   that low.   
      
   ** That would be because you  LOATHE  the Quad II so much you cannot bring   
   yourself to put in the effort to restore one to original specs and  SEE  how   
   well it works.   
      
   Fuck off and die you vile freak.   
      
      
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)