From: phil_a@tpg.com.au   
      
   "GRe"   
    "Phil Allison"   
   >   
   >> You need a THD meter to make sense of what matters and what does not.   
   >>   
   >   
   > Input f/V/THD       Output THD (600ohm terminated)   
   >   
   > 1kHz/1.0V/0.075%    0.082%   
   > 1kHz/3.6V/0.086%    0.101%   
   >   
   > 3.6V is the max. output for the audio generator.   
      
      
   ** You need to use a much lower frequency.   
      
      Transformer non linearity is concentrated  at the low end of the audio   
   band.   
      
      
   > Can one simply substract THD Out/In numbers to gain THD for the   
   > transformer only?   
      
      
   ** To a rough approximation only.   
      
   The figures quoted above suggest the tranny is adding almost nothing.   
      
   PLUS it is crucial the source impedance be low - like 50 or 100 ohms.   
      
   Easy way is to use one channel of a good hi-fi amplifier to buffer the   
   output of the generator and drop the impedance to near zero.   
      
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)