From: phil_a@tpg.com.au   
      
   "John Byrns"   
   >   
   > The only improvement I would make would be to improve the hum and noise   
   > spec.   
   > which is 80 dB below 15 Watts, I would make that 80 dB below 1 Watt.   
   >   
   > It isn't clear what is causing the poor noise spec.,   
      
   ** On my one example ( sn 8734 ) residual noise is mostly 50 Hz hum -   
   shorting or opening the input has no effect, so I the source is probably   
   EF86s heaters.   
      
   Eliminating the hum with a HPF leaves only a soft hiss which, best I can   
   measure, is 90uV rms or about 102 dB below 15 watts. In any normal listening   
   situation, even with efficient speakers ( say 100dB/W/m ) a listener hears   
   silence.   
      
   BTW:   
      
   The THD of my Quad II measures 0.048 % at 10 watts and 0.19 % at 15 watts at   
   1kHz and 8 ohms.   
      
   The EF86s are of unknown brand and decades old, while the output tubes are a   
   pair of well used Sylvania 6L6GCs.   
      
      
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)