XPost: sci.electronics.design   
   From: tauno.voipio@notused.fi.invalid   
      
   On 1.1.19 06:39, Tim Williams wrote:   
   > "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   
   >   
      
   The final triodes (6080) are special high-current tubes. The amplifier   
   designer rated the thing at 25 W into a 16 ohm voice-coil speaker.   
      
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