XPost: sci.electronics.design   
   From: tiwill@seventransistorlabs.com   
      
   "Big Bad Bob"  wrote in message   
   news:R6mdnYGk2c0E97fBnZ2dnUU7-LPNnZ2d@earthlink.com...   
   > sounds like a gimmick.  Tube plate/cathode currents are just way too small   
   > to properly drive a speaker without an impedence matching transformer.   
   >   
      
   So what, nothing comes out?...   
      
   They were definitely below the maximum power point (at clipping), if that's   
   more accurately what you meant.   
      
   6AS7/6080, 6S33S and the other regulator tubes have peak cathode current in   
   the ballpark of an ampere, so a modest number of tubes offers a modest power   
   output, say 20 or 40W, preferably into a higher load like 16 ohms.  The   
   efficiency is poor, with more heat dissipated in the heaters alone, than   
   delivered to the output.   
      
   If you put dozens in parallel, the efficiency keeps going up as you get   
   closer to matching, but now your whole system consumes multiple kilowatts...   
      
   There was also the Philips "SEPP" with a pair of EL86? driving a 100s-ohms   
   voice coil at good efficiency, but those speakers are so rare that this is   
   practically a unique case.   
      
   Tim   
      
   --   
   Seven Transistor Labs, LLC   
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